[ruby-core:121702] [Ruby Bug#21280] StringIO#set_encoding warns when backed by chilled string literal

Issue #21280 has been reported by jeremyevans0 (Jeremy Evans). ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by byroot (Jean Boussier).
Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)?
I think the current behavior is correct in the sense that "chilled strings" are mutable strings, hence should behave just like a mutable string. In this case it means changing the encoding. Chilled strings should also emit a warning when they are mutated to signal that the behavior will change if `--enable-frozen-string-literal` is turned on, which it does right now. Based on that I think the current behavior is correct, this warning is correctly warning you action is needed here. ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-112762 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by jeremyevans0 (Jeremy Evans). byroot (Jean Boussier) wrote in #note-1:
Chilled strings should also emit a warning when they are mutated to signal that the behavior will change if `--enable-frozen-string-literal` is turned on, which it does right now.
But behavior in this case will not change if `--enable-frozen-string-literal` is turned on, because `StringIO#set_encoding` does not set the encoding of the underlying string for frozen strings.
Based on that I think the current behavior is correct, this warning is correctly warning you action is needed here.
But no action is needed. Things will automatically work when strings move from chilled by default to frozen by default, because `StringIO#set_encoding` will not try to change the encoding of the underlying string in that case. ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-112763 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by byroot (Jean Boussier).
But behavior in this case will not change
Maybe I'm missing something, but I think the behavior will change: ```
StringIO.new("").set_encoding(Encoding::BINARY).string.encoding (irb):7: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) => #<Encoding:BINARY (ASCII-8BIT)> StringIO.new(+"").set_encoding(Encoding::BINARY).string.encoding => #<Encoding:BINARY (ASCII-8BIT)> StringIO.new("".freeze).set_encoding(Encoding::BINARY).string.encoding => #<Encoding:UTF-8>
----------------------------------------
Bug #21280: StringIO#set_encoding warns when backed by chilled string literal
https://bugs.ruby-lang.org/issues/21280#change-112764
* Author: jeremyevans0 (Jeremy Evans)
* Status: Open
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
`StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings:
$ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by jeremyevans0 (Jeremy Evans). byroot (Jean Boussier) wrote in #note-3:
But behavior in this case will not change
Maybe I'm missing something, but I think the behavior will change:
```ruby
StringIO.new("").set_encoding(Encoding::BINARY).string.encoding (irb):7: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) => #<Encoding:BINARY (ASCII-8BIT)> StringIO.new(+"").set_encoding(Encoding::BINARY).string.encoding => #<Encoding:BINARY (ASCII-8BIT)> StringIO.new("".freeze).set_encoding(Encoding::BINARY).string.encoding => #<Encoding:UTF-8>
The full sentence was:
But behavior in this case will not change if `--enable-frozen-string-literal` is turned on, because StringIO#set_encoding does not set the encoding of the underlying string for frozen strings.
With the patch, `StringIO#set_encoding` treats a chilled string as a frozen string, so behavior when `--enable-frozen-string-literal` is turned on does not change. The present situation is that `--enable-frozen-string-literal` changes behavior of `StringIO#set_encoding`. ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-112770 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by byroot (Jean Boussier). Perhaps it's the jetlag talking, but I think the current behavior is desirable. Chilled string as designed should behave like mutable strings, and warn when a frozen one would have behaved differently. Isn't that the current behavior? ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-112771 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by jeremyevans0 (Jeremy Evans). byroot (Jean Boussier) wrote in #note-5:
Chilled string as designed should behave like mutable strings, and warn when a frozen one would have behaved differently. Isn't that the current behavior?
In this case, a frozen string would not behave differently, since `StringIO#set_encoding` treats frozen strings differently than it does unfrozen strings. The purpose of chilled strings is to warn users when code will break when the strings are frozen. Since code will not break in this case, issuing a warning seems like a bad idea, as it will prompt code changes when none are actually needed. ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-112772 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by byroot (Jean Boussier).
Since code will not break in this case
That is debatable. It won't raise an exception yes, but the behavior will change as you can see in the IRB session I shared. ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-112773 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by Eregon (Benoit Daloze). I think just removing the warning is not right here (also explicitly testing for chilled strings feels dirty). I think callers of StringIO.new should not pass a frozen String, at least if any StringIO "write" method is used, and I consider StringIO#set_encoding to be a "write" method (since currently in the non-frozen cases it does mutate the String). Fundamentally the behavior of setting the encoding of the String only if it's not frozen for StringIO#set_encoding is inconsistent/broken/brittle, it might very much break things because AFAIK it affects the encoding of the string returned by StringIO#string. So from that I can see two solutions: * StringIO#set_encoding never sets the String encoding, but that is a potentially breaking change (though it would address the fundamentals, so I think worth a try). * People should not use frozen strings with StringIO if they then use "write" methods on the StringIO. I think we should warn for both frozen and chilled strings in StringIO#set_encoding, to tell users they shouldn't pass a frozen string + call StringIO#set_encoding (they can probably set the encoding when creating the StringIO instead, or pass a non-frozen String). ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-112791 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by jeremyevans0 (Jeremy Evans). It seems like most developers are against treating chilled strings differently than unfrozen strings in this case. I can understand that, since that's usually the best course of action. As an alternative, we could remove the setting of the underlying string encoding in all cases. Then behavior is the same for chilled strings, unfrozen strings, and frozen strings. @naruse already mentioned that this was ideal in https://bugs.ruby-lang.org/issues/11827#note-3, but wasn't sure if it was worth breaking backwards compatibility. I think avoiding a bogus warning for chilled strings is worth it, assuming there isn't significant breakage elsewhere. The example in https://bugs.ruby-lang.org/issues/11827#note-4 shouldn't be affected, since as I mentioned earlier, `StringIO` takes the `elsif self.respond_to? :string` branch, not the `else` branch. I've submitted a pull request to implement this: https://github.com/ruby/stringio/pull/132 . I think either approach is fine, as long as the bogus warning is avoided. ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-112868 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by mame (Yusuke Endoh). Discussed at the dev meeting. @matz said that he prefers not to issue warnings that could be false positives, even if they are true positives in many cases. The code `StringIO.new("").set_encoding('binary')` will work even in future as long as StringIO is used read-only. Therefore, this warning could be a false positive, and it would be nice to stop this warning in `StringIO#set_encoding`. In code that needs to be changed (i.e., the StringIO is used as read-write mode), it is expected that a warning will be finally issued by `StringIO#write` or something after a while, even if we don't issue the warning in `StringIO#set_encoding`. ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-113032 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by Eregon (Benoit Daloze). https://github.com/ruby/stringio/pull/132 is a much cleaner solution, was it considered? (https://bugs.ruby-lang.org/issues/21281 doesn't have the log yet so I can't check that) ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-113053 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/

Issue #21280 has been updated by jeremyevans0 (Jeremy Evans). Status changed from Open to Closed Fixed by commit:18d395e0784401585b5c14300e689de55e208647 ---------------------------------------- Bug #21280: StringIO#set_encoding warns when backed by chilled string literal https://bugs.ruby-lang.org/issues/21280#change-113186 * Author: jeremyevans0 (Jeremy Evans) * Status: Closed * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- `StringIO#set_encoding` changes the underlying string encoding if the string is not frozen, but does not change the underlying string encoding if the string is frozen. In Ruby 3.4, this results in a warning for chilled literal strings: ``` $ ruby34 -w -r stringio -e "StringIO.new('').set_encoding('binary')" -e:1: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information) ``` I believe Ruby should emit this warning only for cases that will break when string literals are frozen. This is not one of those cases, so Ruby should not emit the warning. To avoid emitting the warning, I think `StringIO#set_encoding` should not set the encoding on the underlying string for chilled literal strings. I submitted a pull request to avoid changing the encoding of the underlying string: https://github.com/ruby/stringio/pull/128 However, @rhenium said that he thought the encoding of the underlying string should still be changed, and the warning should be emitted (https://github.com/ruby/stringio/pull/128#issuecomment-2818362875). For some history, before Ruby 2.3, `StringIO#set_encoding` used to always set the encoding of the underlying string. This was changed in #11827, when the encoding was not set on the underlying string if the string was frozen (commit:3e1c01ae463a8c9d8bbe9050251a2538ddb0292f). In https://bugs.ruby-lang.org/issues/11827#note-3, @nurse wrote:
Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding. But I'm not sure that it is worth breaking the compatibility.
I think this means that ideally, absent backwards compatibility issues, StringIO#set_encoding should never change the underlying string encoding. In https://bugs.ruby-lang.org/issues/11827#note-4, @shugo gave an example from @nobu that open-uri depends on the current behavior: ```ruby enc = Encoding::ASCII_8BIT unless enc if self.respond_to? :force_encoding self.force_encoding(enc) elsif self.respond_to? :string self.string.force_encoding(enc) else # Tempfile self.set_encoding enc end end ``` However, as `StringIO#string` is defined, this will call `self.string.force_encoding(enc)` and not `self.set_encoding enc`, so I'm not sure why a change to `String#set_encoding` would affect the behavior of this example. @rhenium pointed out that this issue affects `StringIO#binmode` and `StringIO#set_encoding_by_bom` as well as `StringIO#encoding`. How do we want to handle this case? Should this result in a warning (current behavior), or is it safe to avoid changing the encoding of the underlying string for chilled strings (as is done for frozen strings)? -- https://bugs.ruby-lang.org/
participants (4)
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byroot (Jean Boussier)
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Eregon (Benoit Daloze)
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jeremyevans0 (Jeremy Evans)
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mame (Yusuke Endoh)