April 2024 - ruby-core - ml.ruby-lang.org

[ruby-core:117602] [Ruby master Feature#15554] warn/error passing a block to a method which never use a block
by Dan0042 (Daniel DeLorme) 19 Apr '24

19 Apr '24

Issue #15554 has been updated by Dan0042 (Daniel DeLorme). byroot (Jean Boussier) wrote in #note-26: > So I'd expect `block_given?` to qualify as "using the block". But I suppose it's tricky because `block_given?` is just a method like any other for the compiler? I would also expect `block_given?` to qualify as "using the block", and I don't think there's any need to overthink it because it's just a method. If `block_given?` is present, do not show the warning. In the unlikely case that `block_given?` was actually a redefined method, then the warning is not displayed even if it should, and that's not really a serious issue. byroot (Jean Boussier) wrote in #note-28: > - It generated some false positive because of `...` delegation for methods that don't accept a block. I don't understand that one. `...` delegation doesn't "create" a block that is then passed down the chain. If you have `foo(1,2,3)` without a block that is delegated via `...` to `def bar(x,y,z) = x+y+z` then it shouldn't print a warning. But if you have `foo(1,2,3){ }` that is delegated via `...` to that same `bar` then it *should* print a warning, right? ko1 (Koichi Sasada) wrote in #note-29: > Matz hesitates to force to put `&_` (or other tricks) for duck typing methods I don't understand this duck typing argument. Normally, duck typing requires a method to have the same name AND arguments (or at least a compatible signature). ```ruby a = Object.new def a.foo(x,y) = nil b = Object.new def b.foo(x) = nil (rand<0.5 ? a : b).foo(1,2) #raises error 50% of the time; different arity = not duck-compatible ``` It's commonly understood that in order to have `a` and `b` be duck-compatible, their `foo` method must accept the same arguments. So if you want `b` to ignore an argument you'd have to define it like this: `def b.foo(x, dummy=nil) = nil` Blocks are a type of argument, so the same should apply; in order for `ActiveModel::Attribute#value` and `ActiveModel::Attribute::Uninitialized#value` to be duck-compatible, they should both take a block or neither take a block. The fact that it hasn't been the case until now is more like a quirk of the language that has resulted in many facepalm bugs. `ActiveModel::Attribute#value` should be defined with `&` to indicate that this method receives a block, and ignores it. ---------------------------------------- Feature #15554: warn/error passing a block to a method which never use a block https://bugs.ruby-lang.org/issues/15554#change-108011 * Author: ko1 (Koichi Sasada) * Status: Closed * Assignee: matz (Yukihiro Matsumoto) ---------------------------------------- # Abstract Warn or raise an ArgumentError if block is passed to a method which does not use a block. In other words, detect "block user methods" implicitly and only "block user methods" can accept a block. # Background Sometimes, we pass a block to a method which ignores the passed block accidentally. ``` def my_open(name) open(name) end # user hopes it works as Kernel#open which invokes a block with opened file. my_open(name){|f| important_work_with f } # but simply ignored... ``` To solve this issue, this feature request propose showing warnings or raising an exception on such case. Last developer's meeting, matz proposed `&nil` which declares this method never receive a block. It is explicit, but it is tough to add this `&nil` parameter declaration to all of methods (do you want to add it to `def []=(i, e, &nil)`?). (I agree `&nil` is valuable on some situations) # Spec ## Define "use a block" methods We need to define which method accepts a block and which method does not. * (1) method has a block parameter (`&b`) * (2) method body has `yield' * (3) method body has `super` (ZSUPER in internal terminology) or `super(...)` * (4) method body has singleton method (optional) (1) and (2) is very clear. I need to explain about (3) and (4). (3). `super` (ZSUPER) passes all parameters as arguments. So there is no surprise that which can accept `block`. However `super(...)` also passes a block if no explicit block passing (like `super(){}` or `super(&b)`) are written. I'm not sure we need to continue this strange specification, but to keep compatibility depending this spec, I add this rule. (4). surprisingly, the following code invoke a block: ``` def foo class << Object.new yield end end foo{ p :ok } #=> :ok ``` I'm also not sure we need to keep this spec, but to allow this spec, I added (4) rule. Strictly speaking, it is not required, but we don't keep the link from singleton class ISeq to lexical parent iseq now, so I added it. ## Exceptional cases A method called by `super` doesn`t warn warning even if this method doesn't use a block. The rule (3) can pass blocks easily and there are many methods don`t use a block. So my patch ignores callings by `super`. ## corner cases There are several cases to use block without (1)-(4) rules. ### `Proc.new/proc/lambda` without a block Now it was deprecated in r66772 (commit:9f1fb0a17febc59356d58cef5e98db61a3c03550). Related discussion: [Bug #15539] ### `block_given?` `block_given?` expects block, but I believe we use it with `yield` or a block parameter. If you know the usecase without them, please tell us. ### `yield` in `eval` We can't know `yield` (or (3), (4) rule) in an `eval` evaluating string at calling time. ``` def foo eval('yield`) end foo{} # at calling time, # we can't know the method foo can accept a block or not. ``` So I added a warning to use `yield` in `eval` like that: `test.rb:4: warning: use yield in eval will not be supported in Ruby 3.` Workaround is use a block parameter explicitly. ``` def foo &b eval('b.call') end foo{ p :ok } ``` # Implementation Strategy is: * [compile time] introduce `iseq::has_yield` field and check it if the iseq (or child iseq) contains `yield` (or something) * [calling time] if block is given, check `iseq::has_yield` flag and show warning (or raise an exception) https://gist.github.com/ko1/c9148ad0224bf5befa3cc76ed2220c0b On this patch, now it raises an error to make it easy to detect. It is easy to switch to show the warning. # Evaluation and discussion I tried to avoid ruby's tests. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786 Here is a patch. There are several patterns to avoid warnings. ## tests for `block_given?`, `Proc.new` (and similar) without block Add a dummy block parameter. It is test-specific issue. ## empty `each` Some tests add `each` methods do not `yield`, like: `def each; end`. Maybe test-specific issue, and adding a dummy block parameter. ## Subtyping / duck typing https://github.com/ruby/ruby/blob/c01a5ee85e2d6a7128cccafb143bfa694284ca87/… This `parse` method doesn't use `yield`, but other sub-type's `parse` methods use. ## `super` with `new` method https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… This method override `Class#new` method and introduce a hook with block (yield a block in this hook code). https://github.com/ruby/ruby/blob/trunk/lib/rubygems/package/tar_writer.rb#… In this method, call `super` and it also passing a block. However, called `initialize` doesn't use a block. ## Change robustness This change reduce robustness for API change. `Delegator` requires to support `__getobj__` for client classes. Now `__getobj__` should accept block but most of `__getobj__` clients do not call given block. https://github.com/ruby/ruby/blob/trunk/lib/delegate.rb#L80 This is because of delegator.rb's API change. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… Nobu says calling block is not required (ignoring a block is no problem) so it is not a bug for delegator client classes. ## Found issues. ``` [ 2945/20449] Rinda::TestRingServer#test_do_reply = 0.00 s 1) Error: Rinda::TestRingServer#test_do_reply: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:635:in `test_do_reply' [ 2946/20449] Rinda::TestRingServer#test_do_reply_local = 0.00 s 2) Error: Rinda::TestRingServer#test_do_reply_local: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:657:in `test_do_reply_local' [10024/20449] TestGemRequestSetGemDependencyAPI#test_platform_mswin = 0.01 s 3) Error: TestGemRequestSetGemDependencyAPI#test_platform_mswin: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:655:in `test_platform_mswin' [10025/20449] TestGemRequestSetGemDependencyAPI#test_platforms = 0.01 s 4) Error: TestGemRequestSetGemDependencyAPI#test_platforms: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:711:in `test_platforms' ``` These 4 detection show the problem. `with_timeout` method (used in Rinda test) and `util_set_arch` method (used in Rubygems test) simply ignore the given block. So these tests are simply ignored. I reported them. (https://github.com/rubygems/rubygems/issues/2601) ## raise an error or show a warning? At least, Ruby 2.7 should show warning for this kind of violation with `-w`. How about for Ruby3? -- https://bugs.ruby-lang.org/

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[ruby-core:117568] [Ruby master Misc#20434] Deprecate regular expression modifiers
by kddnewton (Kevin Newton) 18 Apr '24

18 Apr '24

Issue #20434 has been reported by kddnewton (Kevin Newton). ---------------------------------------- Misc #20434: Deprecate regular expression modifiers https://bugs.ruby-lang.org/issues/20434 * Author: kddnewton (Kevin Newton) * Status: Open ---------------------------------------- This is a follow-up to @duerst's comment here: https://bugs.ruby-lang.org/issues/20406#note-6. As noted in the other issue, there are many encodings that factor in to how a regular expression operates. This includes: * The encoding of the file * The encoding of the string parts within the regular expression * The regular expression encoding modifiers * The encoding of the string being matched At the time the modifiers were introduced, I believe the modifiers may have been the only (??) encoding that factored in here. At this point, however, they can lead to quite a bit of confusion, as noted in the other ticket. I would like to propose to deprecate the regular expression encoding modifiers. Instead, we could suggest in a warning to instead create a regular expression with an encoded string. For example, when we find: ```ruby /\x81\x40/s ``` we would instead suggest: ```ruby ::Regexp.new(::String.new("\x81\x40", encoding: "Windows-31J")) ``` or equivalent. As a migration path, we could do the following: 1. Emit a warning to change to the suggested expression 2. Change the compiler to compile to the suggested expression when those flags are found 3. Remove support for the flags Step 2 may be unnecessary depending on how long of a timeline we would like to provide. To be clear, I'm not advocating for any particular timeline, and would be fine with this being multiple years/versions to give plenty of time for people to migrate. But I do think this would be a good change to eliminate confusion about the interaction between the four different encodings at play. -- https://bugs.ruby-lang.org/

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[ruby-core:117157] [Ruby master Misc#20336] DevMeeting-2024-04-17
by mame (Yusuke Endoh) 18 Apr '24

18 Apr '24

Issue #20336 has been reported by mame (Yusuke Endoh). ---------------------------------------- Misc #20336: DevMeeting-2024-04-17 https://bugs.ruby-lang.org/issues/20336 * Author: mame (Yusuke Endoh) * Status: Open ---------------------------------------- # The next dev meeting **Date: 2024/04/17 13:00-17:00** (JST) Log: *TBD* - Dev meeting *IS NOT* a decision-making place. All decisions should be done at the bug tracker. - Dev meeting is a place we can ask Matz, nobu, nurse and other developers directly. - Matz is a very busy person. Take this opportunity to ask him. If you can not attend, other attendees can ask instead of you (if attendees can understand your issue). - We will write a record of the discussion in the file or to each ticket in English. - All activities are best-effort (keep in mind that most of us are volunteer developers). - The date, time and place of the meeting are scheduled according to when/where we can reserve Matz's time. - *DO NOT* discuss then on this ticket, please. # Call for agenda items If you have a ticket that you want matz and committers to discuss, please post it into this ticket in the following format: ``` * [Ticket ref] Ticket title (your name) * Comment (A summary of the ticket, why you put this ticket here, what point should be discussed, etc.) ``` Example: ``` * [Feature #14609] `Kernel#p` without args shows the receiver (ko1) * I feel this feature is very useful and some people say :+1: so let discuss this feature. ``` - It is recommended to add a comment by 2024/04/14. We hold a preparatory meeting to create an agenda a few days before the dev-meeting. - The format is strict. We'll use [this script to automatically create an markdown-style agenda](https://gist.github.com/mame/b0390509ce1491b43610b9ebb665eb86). We may ignore a comment that does not follow the format. - Your comment is mandatory. We cannot read all discussion of the ticket in a limited time. We appreciate it if you could write a short summary and update from a previous discussion. -- https://bugs.ruby-lang.org/

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[ruby-core:117598] [Ruby master Feature#15554] warn/error passing a block to a method which never use a block
by Eregon (Benoit Daloze) 18 Apr '24

18 Apr '24

Issue #15554 has been updated by Eregon (Benoit Daloze). With the example from @mame, I think adding `(&)` or `(&on_missing)` for `Attribute::Attribute#value` would be good to clarify the value method can receive a block, and purposefully ignores it. To me it sounds weird that there are method overrides for the same method with "different" signatures. In fact if it was a positional or keyword argument instead of a block argument, one would already need to add e.g. `def value(arg = nil/*/kw: nil/**)` for `Attribute::Attribute#value`. So I think it's good to treat a block argument closer to positional or keyword arguments in this aspect. I understand the other arguments too, notably it does not make the code more beautiful but I think it makes the code clearer. This is clearly to some amount subjective. I suspect it will be very difficult to change matz's opinion on this, at least this feature should still detect some ignored blocks bugs. One more idea is we could emit a different warning message for the cases that would be excluded by the global method name ignore. Then people could easily filter these specific warnings (and keep other block ignored warnings enabled) if they don't want to address that, but would otherwise be able to see all ignored block warnings and address them. ---------------------------------------- Feature #15554: warn/error passing a block to a method which never use a block https://bugs.ruby-lang.org/issues/15554#change-108007 * Author: ko1 (Koichi Sasada) * Status: Closed * Assignee: matz (Yukihiro Matsumoto) ---------------------------------------- # Abstract Warn or raise an ArgumentError if block is passed to a method which does not use a block. In other words, detect "block user methods" implicitly and only "block user methods" can accept a block. # Background Sometimes, we pass a block to a method which ignores the passed block accidentally. ``` def my_open(name) open(name) end # user hopes it works as Kernel#open which invokes a block with opened file. my_open(name){|f| important_work_with f } # but simply ignored... ``` To solve this issue, this feature request propose showing warnings or raising an exception on such case. Last developer's meeting, matz proposed `&nil` which declares this method never receive a block. It is explicit, but it is tough to add this `&nil` parameter declaration to all of methods (do you want to add it to `def []=(i, e, &nil)`?). (I agree `&nil` is valuable on some situations) # Spec ## Define "use a block" methods We need to define which method accepts a block and which method does not. * (1) method has a block parameter (`&b`) * (2) method body has `yield' * (3) method body has `super` (ZSUPER in internal terminology) or `super(...)` * (4) method body has singleton method (optional) (1) and (2) is very clear. I need to explain about (3) and (4). (3). `super` (ZSUPER) passes all parameters as arguments. So there is no surprise that which can accept `block`. However `super(...)` also passes a block if no explicit block passing (like `super(){}` or `super(&b)`) are written. I'm not sure we need to continue this strange specification, but to keep compatibility depending this spec, I add this rule. (4). surprisingly, the following code invoke a block: ``` def foo class << Object.new yield end end foo{ p :ok } #=> :ok ``` I'm also not sure we need to keep this spec, but to allow this spec, I added (4) rule. Strictly speaking, it is not required, but we don't keep the link from singleton class ISeq to lexical parent iseq now, so I added it. ## Exceptional cases A method called by `super` doesn`t warn warning even if this method doesn't use a block. The rule (3) can pass blocks easily and there are many methods don`t use a block. So my patch ignores callings by `super`. ## corner cases There are several cases to use block without (1)-(4) rules. ### `Proc.new/proc/lambda` without a block Now it was deprecated in r66772 (commit:9f1fb0a17febc59356d58cef5e98db61a3c03550). Related discussion: [Bug #15539] ### `block_given?` `block_given?` expects block, but I believe we use it with `yield` or a block parameter. If you know the usecase without them, please tell us. ### `yield` in `eval` We can't know `yield` (or (3), (4) rule) in an `eval` evaluating string at calling time. ``` def foo eval('yield`) end foo{} # at calling time, # we can't know the method foo can accept a block or not. ``` So I added a warning to use `yield` in `eval` like that: `test.rb:4: warning: use yield in eval will not be supported in Ruby 3.` Workaround is use a block parameter explicitly. ``` def foo &b eval('b.call') end foo{ p :ok } ``` # Implementation Strategy is: * [compile time] introduce `iseq::has_yield` field and check it if the iseq (or child iseq) contains `yield` (or something) * [calling time] if block is given, check `iseq::has_yield` flag and show warning (or raise an exception) https://gist.github.com/ko1/c9148ad0224bf5befa3cc76ed2220c0b On this patch, now it raises an error to make it easy to detect. It is easy to switch to show the warning. # Evaluation and discussion I tried to avoid ruby's tests. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786 Here is a patch. There are several patterns to avoid warnings. ## tests for `block_given?`, `Proc.new` (and similar) without block Add a dummy block parameter. It is test-specific issue. ## empty `each` Some tests add `each` methods do not `yield`, like: `def each; end`. Maybe test-specific issue, and adding a dummy block parameter. ## Subtyping / duck typing https://github.com/ruby/ruby/blob/c01a5ee85e2d6a7128cccafb143bfa694284ca87/… This `parse` method doesn't use `yield`, but other sub-type's `parse` methods use. ## `super` with `new` method https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… This method override `Class#new` method and introduce a hook with block (yield a block in this hook code). https://github.com/ruby/ruby/blob/trunk/lib/rubygems/package/tar_writer.rb#… In this method, call `super` and it also passing a block. However, called `initialize` doesn't use a block. ## Change robustness This change reduce robustness for API change. `Delegator` requires to support `__getobj__` for client classes. Now `__getobj__` should accept block but most of `__getobj__` clients do not call given block. https://github.com/ruby/ruby/blob/trunk/lib/delegate.rb#L80 This is because of delegator.rb's API change. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… Nobu says calling block is not required (ignoring a block is no problem) so it is not a bug for delegator client classes. ## Found issues. ``` [ 2945/20449] Rinda::TestRingServer#test_do_reply = 0.00 s 1) Error: Rinda::TestRingServer#test_do_reply: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:635:in `test_do_reply' [ 2946/20449] Rinda::TestRingServer#test_do_reply_local = 0.00 s 2) Error: Rinda::TestRingServer#test_do_reply_local: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:657:in `test_do_reply_local' [10024/20449] TestGemRequestSetGemDependencyAPI#test_platform_mswin = 0.01 s 3) Error: TestGemRequestSetGemDependencyAPI#test_platform_mswin: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:655:in `test_platform_mswin' [10025/20449] TestGemRequestSetGemDependencyAPI#test_platforms = 0.01 s 4) Error: TestGemRequestSetGemDependencyAPI#test_platforms: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:711:in `test_platforms' ``` These 4 detection show the problem. `with_timeout` method (used in Rinda test) and `util_set_arch` method (used in Rubygems test) simply ignore the given block. So these tests are simply ignored. I reported them. (https://github.com/rubygems/rubygems/issues/2601) ## raise an error or show a warning? At least, Ruby 2.7 should show warning for this kind of violation with `-w`. How about for Ruby3? -- https://bugs.ruby-lang.org/

1 0

[ruby-core:117341] [Ruby master Feature#20396] ObjectSpace.dump_all(string_value: false): skip dumping the String contents
by byroot (Jean Boussier) 18 Apr '24

18 Apr '24

Issue #20396 has been reported by byroot (Jean Boussier). ---------------------------------------- Feature #20396: ObjectSpace.dump_all(string_value: false): skip dumping the String contents https://bugs.ruby-lang.org/issues/20396 * Author: byroot (Jean Boussier) * Status: Open ---------------------------------------- `ObjectSpace.dump_all` is a very useful method to debug memory leaks and such, hence is frequently needed in production. But since all the 7bit strings content is included in the dump, it incur the risk of leaking personal data, or secrets. Also, in many case the strings content isn't that helpful and is just making the dump much bigger for no good reason. And only pure-ASCII strings are dumped this way, which means all the tools that process these dumps should already be compatible with a dump without any string content. ### Feature I propose to add another optional parameter to `dump_all`: `string_value: false`. When passed, no String content is ever dumped regardless of its coderange. Implementation: https://github.com/ruby/ruby/pull/10382 cc @zzak -- https://bugs.ruby-lang.org/

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[ruby-core:117590] [Ruby master Feature#15554] warn/error passing a block to a method which never use a block
by jeremyevans0 (Jeremy Evans) 18 Apr '24

18 Apr '24

Issue #15554 has been updated by jeremyevans0 (Jeremy Evans). One approach that reduces false positives (invalid warnings) and potentially increases false negatives (missing warnings) would be to only warn for literal blocks and not passed blocks: ```ruby def foo end def bar(&) = foo(&) # no warning bar{} foo{} # warning ``` Currently, this generates two warnings: ``` -:4: warning: the block passed to 'Object#foo' defined at -:1 may be ignored -:7: warning: the block passed to 'Object#foo' defined at -:1 may be ignored ``` I propose the first warning be eliminated. In the above example, it is always an error, but in real world code, such as when `foo` is called indirectly using `send`, or when the `foo` method is defined differently for different objects, it may not be an error. Passing a literal block to a method that doesn't accept a block is almost always an error. Passing an existing block to a method that doesn't accept it may or may not be an error. I think it's better to only warn in cases where we are fairly sure it is an error. ---------------------------------------- Feature #15554: warn/error passing a block to a method which never use a block https://bugs.ruby-lang.org/issues/15554#change-107991 * Author: ko1 (Koichi Sasada) * Status: Closed * Assignee: matz (Yukihiro Matsumoto) ---------------------------------------- # Abstract Warn or raise an ArgumentError if block is passed to a method which does not use a block. In other words, detect "block user methods" implicitly and only "block user methods" can accept a block. # Background Sometimes, we pass a block to a method which ignores the passed block accidentally. ``` def my_open(name) open(name) end # user hopes it works as Kernel#open which invokes a block with opened file. my_open(name){|f| important_work_with f } # but simply ignored... ``` To solve this issue, this feature request propose showing warnings or raising an exception on such case. Last developer's meeting, matz proposed `&nil` which declares this method never receive a block. It is explicit, but it is tough to add this `&nil` parameter declaration to all of methods (do you want to add it to `def []=(i, e, &nil)`?). (I agree `&nil` is valuable on some situations) # Spec ## Define "use a block" methods We need to define which method accepts a block and which method does not. * (1) method has a block parameter (`&b`) * (2) method body has `yield' * (3) method body has `super` (ZSUPER in internal terminology) or `super(...)` * (4) method body has singleton method (optional) (1) and (2) is very clear. I need to explain about (3) and (4). (3). `super` (ZSUPER) passes all parameters as arguments. So there is no surprise that which can accept `block`. However `super(...)` also passes a block if no explicit block passing (like `super(){}` or `super(&b)`) are written. I'm not sure we need to continue this strange specification, but to keep compatibility depending this spec, I add this rule. (4). surprisingly, the following code invoke a block: ``` def foo class << Object.new yield end end foo{ p :ok } #=> :ok ``` I'm also not sure we need to keep this spec, but to allow this spec, I added (4) rule. Strictly speaking, it is not required, but we don't keep the link from singleton class ISeq to lexical parent iseq now, so I added it. ## Exceptional cases A method called by `super` doesn`t warn warning even if this method doesn't use a block. The rule (3) can pass blocks easily and there are many methods don`t use a block. So my patch ignores callings by `super`. ## corner cases There are several cases to use block without (1)-(4) rules. ### `Proc.new/proc/lambda` without a block Now it was deprecated in r66772 (commit:9f1fb0a17febc59356d58cef5e98db61a3c03550). Related discussion: [Bug #15539] ### `block_given?` `block_given?` expects block, but I believe we use it with `yield` or a block parameter. If you know the usecase without them, please tell us. ### `yield` in `eval` We can't know `yield` (or (3), (4) rule) in an `eval` evaluating string at calling time. ``` def foo eval('yield`) end foo{} # at calling time, # we can't know the method foo can accept a block or not. ``` So I added a warning to use `yield` in `eval` like that: `test.rb:4: warning: use yield in eval will not be supported in Ruby 3.` Workaround is use a block parameter explicitly. ``` def foo &b eval('b.call') end foo{ p :ok } ``` # Implementation Strategy is: * [compile time] introduce `iseq::has_yield` field and check it if the iseq (or child iseq) contains `yield` (or something) * [calling time] if block is given, check `iseq::has_yield` flag and show warning (or raise an exception) https://gist.github.com/ko1/c9148ad0224bf5befa3cc76ed2220c0b On this patch, now it raises an error to make it easy to detect. It is easy to switch to show the warning. # Evaluation and discussion I tried to avoid ruby's tests. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786 Here is a patch. There are several patterns to avoid warnings. ## tests for `block_given?`, `Proc.new` (and similar) without block Add a dummy block parameter. It is test-specific issue. ## empty `each` Some tests add `each` methods do not `yield`, like: `def each; end`. Maybe test-specific issue, and adding a dummy block parameter. ## Subtyping / duck typing https://github.com/ruby/ruby/blob/c01a5ee85e2d6a7128cccafb143bfa694284ca87/… This `parse` method doesn't use `yield`, but other sub-type's `parse` methods use. ## `super` with `new` method https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… This method override `Class#new` method and introduce a hook with block (yield a block in this hook code). https://github.com/ruby/ruby/blob/trunk/lib/rubygems/package/tar_writer.rb#… In this method, call `super` and it also passing a block. However, called `initialize` doesn't use a block. ## Change robustness This change reduce robustness for API change. `Delegator` requires to support `__getobj__` for client classes. Now `__getobj__` should accept block but most of `__getobj__` clients do not call given block. https://github.com/ruby/ruby/blob/trunk/lib/delegate.rb#L80 This is because of delegator.rb's API change. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… Nobu says calling block is not required (ignoring a block is no problem) so it is not a bug for delegator client classes. ## Found issues. ``` [ 2945/20449] Rinda::TestRingServer#test_do_reply = 0.00 s 1) Error: Rinda::TestRingServer#test_do_reply: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:635:in `test_do_reply' [ 2946/20449] Rinda::TestRingServer#test_do_reply_local = 0.00 s 2) Error: Rinda::TestRingServer#test_do_reply_local: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:657:in `test_do_reply_local' [10024/20449] TestGemRequestSetGemDependencyAPI#test_platform_mswin = 0.01 s 3) Error: TestGemRequestSetGemDependencyAPI#test_platform_mswin: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:655:in `test_platform_mswin' [10025/20449] TestGemRequestSetGemDependencyAPI#test_platforms = 0.01 s 4) Error: TestGemRequestSetGemDependencyAPI#test_platforms: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:711:in `test_platforms' ``` These 4 detection show the problem. `with_timeout` method (used in Rinda test) and `util_set_arch` method (used in Rubygems test) simply ignore the given block. So these tests are simply ignored. I reported them. (https://github.com/rubygems/rubygems/issues/2601) ## raise an error or show a warning? At least, Ruby 2.7 should show warning for this kind of violation with `-w`. How about for Ruby3? -- https://bugs.ruby-lang.org/

1 0

[ruby-core:116892] [Ruby master Misc#20287] DevMeeting before or after RubyKaigi
by duerst 18 Apr '24

18 Apr '24

Issue #20287 has been reported by duerst (Martin Dürst). ---------------------------------------- Misc #20287: DevMeeting before or after RubyKaigi https://bugs.ruby-lang.org/issues/20287 * Author: duerst (Martin Dürst) * Status: Open * Priority: Normal ---------------------------------------- RubyKaigi itself runs from May 15-17 (Wed-Fri) in Naha. It would be nice to have a DevMeeting before or afterwards. We should try to plan ahead, so that people can make the right flight and hotel reservations early. I have never been to Okinawa before and don't know any facilities that would be available. -- https://bugs.ruby-lang.org/

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[ruby-core:117586] [Ruby master Feature#15554] warn/error passing a block to a method which never use a block
by mame (Yusuke Endoh) 18 Apr '24

18 Apr '24

Issue #15554 has been updated by mame (Yusuke Endoh). I was also in the camp that `(&)` should be just added, but after analyzing one warning of rails at the dev meeting, I am now a little less sure. I will try to explain my feelings. --- This call passes a block. ```ruby read_attribute(attr_name) { |n| missing_attribute(n, caller) } ``` https://github.com/rails/rails/blob/6f0d1ad14b92b9f5906e44740fce8b4f1c7075d… After [one delegation](https://github.com/rails/rails/blob/6f0d1ad14b92b9f5906e44740fc…, the block is delegated to `fetch_value` method. ```ruby def fetch_value(name, &block) self[name].value(&block) end ``` https://github.com/rails/rails/blob/6f0d1ad14b92b9f5906e44740fce8b4f1c7075d… Here, `self[name]` is usually an instance of `ActiveModel::Attribute`, so the block is passed to `ActiveModel::Attribute#value`. But it does not accept a block. ``` def value # `defined?` is cheaper than `||=` when we get back falsy values @value = type_cast(value_before_type_cast) unless defined?(@value) @value end ``` https://github.com/rails/rails/blob/6f0d1ad14b92b9f5906e44740fce8b4f1c7075d… So the warning is issued. I think the reason why the block is passed is because `self[name]` is sometimes an instance of `ActiveModel::Attribute::Uninitialized`, whose `#value` method accepts a block. ```ruby def value if block_given? yield name end end ``` https://github.com/rails/rails/blob/6f0d1ad14b92b9f5906e44740fce8b4f1c7075d… --- It is trivial how to stop the warning. Just replace `def value` with `def value(&)`. The problem itself was pointed out by @ko1 with an abstract code example in https://bugs.ruby-lang.org/issues/15554#note-29. I had thought it was okay to add `(&)`. However, when I saw the above example in rails, I was less sure. If Ruby requires a change in the code, I hope that change itself is an improvement of the code, such as, the code becomes more beautiful, shorter, more concise, clearer, etc. For example, this warning tends to require many test mock methods to accept `(&)` explicitly. I don't mind this, because I feel that it benefits the test code itself. It clarifies the test to explicitly state that the mock method would accept the block. Also, the fact that the mock method just discards a block may indicate a lack of test case. However, I cannot justify adding `(&)` to the current definition of `ActiveModel::Attribute#value`. The code is concise enough, and there is no flaw. Just for consistency with the special case `ActiveModel::Attribute::Uninitialized#value`, it is not desirable to pollute the code of the major case `ActiveModel::Attribute#value`. Of course, I understand the benefit of "easier to find bugs in other code", but I am not comfortable sacrificing innocent and beautiful code for that. ---------------------------------------- Feature #15554: warn/error passing a block to a method which never use a block https://bugs.ruby-lang.org/issues/15554#change-107986 * Author: ko1 (Koichi Sasada) * Status: Closed * Assignee: matz (Yukihiro Matsumoto) ---------------------------------------- # Abstract Warn or raise an ArgumentError if block is passed to a method which does not use a block. In other words, detect "block user methods" implicitly and only "block user methods" can accept a block. # Background Sometimes, we pass a block to a method which ignores the passed block accidentally. ``` def my_open(name) open(name) end # user hopes it works as Kernel#open which invokes a block with opened file. my_open(name){|f| important_work_with f } # but simply ignored... ``` To solve this issue, this feature request propose showing warnings or raising an exception on such case. Last developer's meeting, matz proposed `&nil` which declares this method never receive a block. It is explicit, but it is tough to add this `&nil` parameter declaration to all of methods (do you want to add it to `def []=(i, e, &nil)`?). (I agree `&nil` is valuable on some situations) # Spec ## Define "use a block" methods We need to define which method accepts a block and which method does not. * (1) method has a block parameter (`&b`) * (2) method body has `yield' * (3) method body has `super` (ZSUPER in internal terminology) or `super(...)` * (4) method body has singleton method (optional) (1) and (2) is very clear. I need to explain about (3) and (4). (3). `super` (ZSUPER) passes all parameters as arguments. So there is no surprise that which can accept `block`. However `super(...)` also passes a block if no explicit block passing (like `super(){}` or `super(&b)`) are written. I'm not sure we need to continue this strange specification, but to keep compatibility depending this spec, I add this rule. (4). surprisingly, the following code invoke a block: ``` def foo class << Object.new yield end end foo{ p :ok } #=> :ok ``` I'm also not sure we need to keep this spec, but to allow this spec, I added (4) rule. Strictly speaking, it is not required, but we don't keep the link from singleton class ISeq to lexical parent iseq now, so I added it. ## Exceptional cases A method called by `super` doesn`t warn warning even if this method doesn't use a block. The rule (3) can pass blocks easily and there are many methods don`t use a block. So my patch ignores callings by `super`. ## corner cases There are several cases to use block without (1)-(4) rules. ### `Proc.new/proc/lambda` without a block Now it was deprecated in r66772 (commit:9f1fb0a17febc59356d58cef5e98db61a3c03550). Related discussion: [Bug #15539] ### `block_given?` `block_given?` expects block, but I believe we use it with `yield` or a block parameter. If you know the usecase without them, please tell us. ### `yield` in `eval` We can't know `yield` (or (3), (4) rule) in an `eval` evaluating string at calling time. ``` def foo eval('yield`) end foo{} # at calling time, # we can't know the method foo can accept a block or not. ``` So I added a warning to use `yield` in `eval` like that: `test.rb:4: warning: use yield in eval will not be supported in Ruby 3.` Workaround is use a block parameter explicitly. ``` def foo &b eval('b.call') end foo{ p :ok } ``` # Implementation Strategy is: * [compile time] introduce `iseq::has_yield` field and check it if the iseq (or child iseq) contains `yield` (or something) * [calling time] if block is given, check `iseq::has_yield` flag and show warning (or raise an exception) https://gist.github.com/ko1/c9148ad0224bf5befa3cc76ed2220c0b On this patch, now it raises an error to make it easy to detect. It is easy to switch to show the warning. # Evaluation and discussion I tried to avoid ruby's tests. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786 Here is a patch. There are several patterns to avoid warnings. ## tests for `block_given?`, `Proc.new` (and similar) without block Add a dummy block parameter. It is test-specific issue. ## empty `each` Some tests add `each` methods do not `yield`, like: `def each; end`. Maybe test-specific issue, and adding a dummy block parameter. ## Subtyping / duck typing https://github.com/ruby/ruby/blob/c01a5ee85e2d6a7128cccafb143bfa694284ca87/… This `parse` method doesn't use `yield`, but other sub-type's `parse` methods use. ## `super` with `new` method https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… This method override `Class#new` method and introduce a hook with block (yield a block in this hook code). https://github.com/ruby/ruby/blob/trunk/lib/rubygems/package/tar_writer.rb#… In this method, call `super` and it also passing a block. However, called `initialize` doesn't use a block. ## Change robustness This change reduce robustness for API change. `Delegator` requires to support `__getobj__` for client classes. Now `__getobj__` should accept block but most of `__getobj__` clients do not call given block. https://github.com/ruby/ruby/blob/trunk/lib/delegate.rb#L80 This is because of delegator.rb's API change. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… Nobu says calling block is not required (ignoring a block is no problem) so it is not a bug for delegator client classes. ## Found issues. ``` [ 2945/20449] Rinda::TestRingServer#test_do_reply = 0.00 s 1) Error: Rinda::TestRingServer#test_do_reply: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:635:in `test_do_reply' [ 2946/20449] Rinda::TestRingServer#test_do_reply_local = 0.00 s 2) Error: Rinda::TestRingServer#test_do_reply_local: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:657:in `test_do_reply_local' [10024/20449] TestGemRequestSetGemDependencyAPI#test_platform_mswin = 0.01 s 3) Error: TestGemRequestSetGemDependencyAPI#test_platform_mswin: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:655:in `test_platform_mswin' [10025/20449] TestGemRequestSetGemDependencyAPI#test_platforms = 0.01 s 4) Error: TestGemRequestSetGemDependencyAPI#test_platforms: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:711:in `test_platforms' ``` These 4 detection show the problem. `with_timeout` method (used in Rinda test) and `util_set_arch` method (used in Rubygems test) simply ignore the given block. So these tests are simply ignored. I reported them. (https://github.com/rubygems/rubygems/issues/2601) ## raise an error or show a warning? At least, Ruby 2.7 should show warning for this kind of violation with `-w`. How about for Ruby3? -- https://bugs.ruby-lang.org/

1 0

[ruby-core:117584] [Ruby master Feature#15554] warn/error passing a block to a method which never use a block
by akr (Akira Tanaka) 18 Apr '24

18 Apr '24

Issue #15554 has been updated by akr (Akira Tanaka). I encouraged the idea of filtering out the warnings by method name at yesterday's meeting. There were several ideas: (1) force to add &_ for many methods (matz don't like) (2) filter warnings by method name (discussed and implemented now) (3) revert this warning and hope a type checker will generate this warning more precisely. (assuming &_ information is described in type signatures) I encouraged the filtering because I guess the filtering reduces most of the false positives (useless warning emissions). I guess the filtering is better than reverting this warning. A type checker for Ruby is not popular yet. ---------------------------------------- Feature #15554: warn/error passing a block to a method which never use a block https://bugs.ruby-lang.org/issues/15554#change-107984 * Author: ko1 (Koichi Sasada) * Status: Closed * Assignee: matz (Yukihiro Matsumoto) ---------------------------------------- # Abstract Warn or raise an ArgumentError if block is passed to a method which does not use a block. In other words, detect "block user methods" implicitly and only "block user methods" can accept a block. # Background Sometimes, we pass a block to a method which ignores the passed block accidentally. ``` def my_open(name) open(name) end # user hopes it works as Kernel#open which invokes a block with opened file. my_open(name){|f| important_work_with f } # but simply ignored... ``` To solve this issue, this feature request propose showing warnings or raising an exception on such case. Last developer's meeting, matz proposed `&nil` which declares this method never receive a block. It is explicit, but it is tough to add this `&nil` parameter declaration to all of methods (do you want to add it to `def []=(i, e, &nil)`?). (I agree `&nil` is valuable on some situations) # Spec ## Define "use a block" methods We need to define which method accepts a block and which method does not. * (1) method has a block parameter (`&b`) * (2) method body has `yield' * (3) method body has `super` (ZSUPER in internal terminology) or `super(...)` * (4) method body has singleton method (optional) (1) and (2) is very clear. I need to explain about (3) and (4). (3). `super` (ZSUPER) passes all parameters as arguments. So there is no surprise that which can accept `block`. However `super(...)` also passes a block if no explicit block passing (like `super(){}` or `super(&b)`) are written. I'm not sure we need to continue this strange specification, but to keep compatibility depending this spec, I add this rule. (4). surprisingly, the following code invoke a block: ``` def foo class << Object.new yield end end foo{ p :ok } #=> :ok ``` I'm also not sure we need to keep this spec, but to allow this spec, I added (4) rule. Strictly speaking, it is not required, but we don't keep the link from singleton class ISeq to lexical parent iseq now, so I added it. ## Exceptional cases A method called by `super` doesn`t warn warning even if this method doesn't use a block. The rule (3) can pass blocks easily and there are many methods don`t use a block. So my patch ignores callings by `super`. ## corner cases There are several cases to use block without (1)-(4) rules. ### `Proc.new/proc/lambda` without a block Now it was deprecated in r66772 (commit:9f1fb0a17febc59356d58cef5e98db61a3c03550). Related discussion: [Bug #15539] ### `block_given?` `block_given?` expects block, but I believe we use it with `yield` or a block parameter. If you know the usecase without them, please tell us. ### `yield` in `eval` We can't know `yield` (or (3), (4) rule) in an `eval` evaluating string at calling time. ``` def foo eval('yield`) end foo{} # at calling time, # we can't know the method foo can accept a block or not. ``` So I added a warning to use `yield` in `eval` like that: `test.rb:4: warning: use yield in eval will not be supported in Ruby 3.` Workaround is use a block parameter explicitly. ``` def foo &b eval('b.call') end foo{ p :ok } ``` # Implementation Strategy is: * [compile time] introduce `iseq::has_yield` field and check it if the iseq (or child iseq) contains `yield` (or something) * [calling time] if block is given, check `iseq::has_yield` flag and show warning (or raise an exception) https://gist.github.com/ko1/c9148ad0224bf5befa3cc76ed2220c0b On this patch, now it raises an error to make it easy to detect. It is easy to switch to show the warning. # Evaluation and discussion I tried to avoid ruby's tests. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786 Here is a patch. There are several patterns to avoid warnings. ## tests for `block_given?`, `Proc.new` (and similar) without block Add a dummy block parameter. It is test-specific issue. ## empty `each` Some tests add `each` methods do not `yield`, like: `def each; end`. Maybe test-specific issue, and adding a dummy block parameter. ## Subtyping / duck typing https://github.com/ruby/ruby/blob/c01a5ee85e2d6a7128cccafb143bfa694284ca87/… This `parse` method doesn't use `yield`, but other sub-type's `parse` methods use. ## `super` with `new` method https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… This method override `Class#new` method and introduce a hook with block (yield a block in this hook code). https://github.com/ruby/ruby/blob/trunk/lib/rubygems/package/tar_writer.rb#… In this method, call `super` and it also passing a block. However, called `initialize` doesn't use a block. ## Change robustness This change reduce robustness for API change. `Delegator` requires to support `__getobj__` for client classes. Now `__getobj__` should accept block but most of `__getobj__` clients do not call given block. https://github.com/ruby/ruby/blob/trunk/lib/delegate.rb#L80 This is because of delegator.rb's API change. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… Nobu says calling block is not required (ignoring a block is no problem) so it is not a bug for delegator client classes. ## Found issues. ``` [ 2945/20449] Rinda::TestRingServer#test_do_reply = 0.00 s 1) Error: Rinda::TestRingServer#test_do_reply: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:635:in `test_do_reply' [ 2946/20449] Rinda::TestRingServer#test_do_reply_local = 0.00 s 2) Error: Rinda::TestRingServer#test_do_reply_local: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:657:in `test_do_reply_local' [10024/20449] TestGemRequestSetGemDependencyAPI#test_platform_mswin = 0.01 s 3) Error: TestGemRequestSetGemDependencyAPI#test_platform_mswin: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:655:in `test_platform_mswin' [10025/20449] TestGemRequestSetGemDependencyAPI#test_platforms = 0.01 s 4) Error: TestGemRequestSetGemDependencyAPI#test_platforms: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:711:in `test_platforms' ``` These 4 detection show the problem. `with_timeout` method (used in Rinda test) and `util_set_arch` method (used in Rubygems test) simply ignore the given block. So these tests are simply ignored. I reported them. (https://github.com/rubygems/rubygems/issues/2601) ## raise an error or show a warning? At least, Ruby 2.7 should show warning for this kind of violation with `-w`. How about for Ruby3? -- https://bugs.ruby-lang.org/

1 0

[ruby-core:117583] [Ruby master Feature#15554] warn/error passing a block to a method which never use a block
by ko1 (Koichi Sasada) 18 Apr '24

18 Apr '24

Issue #15554 has been updated by ko1 (Koichi Sasada). > I think https://github.com/ruby/ruby/pull/10559 is warning too little, I commented there. Yes. It will reduce many cases and it only warns only a few cases. > I think duck typing cases should be warned, they are potential bugs, it's weird one definition uses the block and another does not, it could very well be that the other definition should use it and it's a bug. > Adding &_ seems good to acknowledge the very rare case of this method might receive a block and ignores it purposefully. I also understand the opinion. quote from my comment: > "Matz hesitates to force to put &_ (or other tricks) for duck typing methods" This is "Ruby"'s language design discussion. So please persuade matz. ---------------------------------------- Feature #15554: warn/error passing a block to a method which never use a block https://bugs.ruby-lang.org/issues/15554#change-107983 * Author: ko1 (Koichi Sasada) * Status: Closed * Assignee: matz (Yukihiro Matsumoto) ---------------------------------------- # Abstract Warn or raise an ArgumentError if block is passed to a method which does not use a block. In other words, detect "block user methods" implicitly and only "block user methods" can accept a block. # Background Sometimes, we pass a block to a method which ignores the passed block accidentally. ``` def my_open(name) open(name) end # user hopes it works as Kernel#open which invokes a block with opened file. my_open(name){|f| important_work_with f } # but simply ignored... ``` To solve this issue, this feature request propose showing warnings or raising an exception on such case. Last developer's meeting, matz proposed `&nil` which declares this method never receive a block. It is explicit, but it is tough to add this `&nil` parameter declaration to all of methods (do you want to add it to `def []=(i, e, &nil)`?). (I agree `&nil` is valuable on some situations) # Spec ## Define "use a block" methods We need to define which method accepts a block and which method does not. * (1) method has a block parameter (`&b`) * (2) method body has `yield' * (3) method body has `super` (ZSUPER in internal terminology) or `super(...)` * (4) method body has singleton method (optional) (1) and (2) is very clear. I need to explain about (3) and (4). (3). `super` (ZSUPER) passes all parameters as arguments. So there is no surprise that which can accept `block`. However `super(...)` also passes a block if no explicit block passing (like `super(){}` or `super(&b)`) are written. I'm not sure we need to continue this strange specification, but to keep compatibility depending this spec, I add this rule. (4). surprisingly, the following code invoke a block: ``` def foo class << Object.new yield end end foo{ p :ok } #=> :ok ``` I'm also not sure we need to keep this spec, but to allow this spec, I added (4) rule. Strictly speaking, it is not required, but we don't keep the link from singleton class ISeq to lexical parent iseq now, so I added it. ## Exceptional cases A method called by `super` doesn`t warn warning even if this method doesn't use a block. The rule (3) can pass blocks easily and there are many methods don`t use a block. So my patch ignores callings by `super`. ## corner cases There are several cases to use block without (1)-(4) rules. ### `Proc.new/proc/lambda` without a block Now it was deprecated in r66772 (commit:9f1fb0a17febc59356d58cef5e98db61a3c03550). Related discussion: [Bug #15539] ### `block_given?` `block_given?` expects block, but I believe we use it with `yield` or a block parameter. If you know the usecase without them, please tell us. ### `yield` in `eval` We can't know `yield` (or (3), (4) rule) in an `eval` evaluating string at calling time. ``` def foo eval('yield`) end foo{} # at calling time, # we can't know the method foo can accept a block or not. ``` So I added a warning to use `yield` in `eval` like that: `test.rb:4: warning: use yield in eval will not be supported in Ruby 3.` Workaround is use a block parameter explicitly. ``` def foo &b eval('b.call') end foo{ p :ok } ``` # Implementation Strategy is: * [compile time] introduce `iseq::has_yield` field and check it if the iseq (or child iseq) contains `yield` (or something) * [calling time] if block is given, check `iseq::has_yield` flag and show warning (or raise an exception) https://gist.github.com/ko1/c9148ad0224bf5befa3cc76ed2220c0b On this patch, now it raises an error to make it easy to detect. It is easy to switch to show the warning. # Evaluation and discussion I tried to avoid ruby's tests. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786 Here is a patch. There are several patterns to avoid warnings. ## tests for `block_given?`, `Proc.new` (and similar) without block Add a dummy block parameter. It is test-specific issue. ## empty `each` Some tests add `each` methods do not `yield`, like: `def each; end`. Maybe test-specific issue, and adding a dummy block parameter. ## Subtyping / duck typing https://github.com/ruby/ruby/blob/c01a5ee85e2d6a7128cccafb143bfa694284ca87/… This `parse` method doesn't use `yield`, but other sub-type's `parse` methods use. ## `super` with `new` method https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… This method override `Class#new` method and introduce a hook with block (yield a block in this hook code). https://github.com/ruby/ruby/blob/trunk/lib/rubygems/package/tar_writer.rb#… In this method, call `super` and it also passing a block. However, called `initialize` doesn't use a block. ## Change robustness This change reduce robustness for API change. `Delegator` requires to support `__getobj__` for client classes. Now `__getobj__` should accept block but most of `__getobj__` clients do not call given block. https://github.com/ruby/ruby/blob/trunk/lib/delegate.rb#L80 This is because of delegator.rb's API change. https://gist.github.com/ko1/37483e7940cdc4390bf8eb0001883786#file-tests-pat… Nobu says calling block is not required (ignoring a block is no problem) so it is not a bug for delegator client classes. ## Found issues. ``` [ 2945/20449] Rinda::TestRingServer#test_do_reply = 0.00 s 1) Error: Rinda::TestRingServer#test_do_reply: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:635:in `test_do_reply' [ 2946/20449] Rinda::TestRingServer#test_do_reply_local = 0.00 s 2) Error: Rinda::TestRingServer#test_do_reply_local: ArgumentError: passing block to the method "with_timeout" (defined at /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:787) is never used. /home/ko1/src/ruby/trunk/test/rinda/test_rinda.rb:657:in `test_do_reply_local' [10024/20449] TestGemRequestSetGemDependencyAPI#test_platform_mswin = 0.01 s 3) Error: TestGemRequestSetGemDependencyAPI#test_platform_mswin: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:655:in `test_platform_mswin' [10025/20449] TestGemRequestSetGemDependencyAPI#test_platforms = 0.01 s 4) Error: TestGemRequestSetGemDependencyAPI#test_platforms: ArgumentError: passing block to the method "util_set_arch" (defined at /home/ko1/src/ruby/trunk/lib/rubygems/test_case.rb:1053) is never used. /home/ko1/src/ruby/trunk/test/rubygems/test_gem_request_set_gem_dependency_api.rb:711:in `test_platforms' ``` These 4 detection show the problem. `with_timeout` method (used in Rinda test) and `util_set_arch` method (used in Rubygems test) simply ignore the given block. So these tests are simply ignored. I reported them. (https://github.com/rubygems/rubygems/issues/2601) ## raise an error or show a warning? At least, Ruby 2.7 should show warning for this kind of violation with `-w`. How about for Ruby3? -- https://bugs.ruby-lang.org/

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