fix: Add AsRef<str> impl for unnamed enums#4478
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udayprakash wants to merge 3 commits intosmithy-lang:mainfrom
Open
fix: Add AsRef<str> impl for unnamed enums#4478udayprakash wants to merge 3 commits intosmithy-lang:mainfrom
udayprakash wants to merge 3 commits intosmithy-lang:mainfrom
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Unnamed enums (newtype string wrappers like `pub struct Foo(String)`) were missing the `AsRef<str>` implementation that named enums have. This caused compilation errors when using unnamed enums with APIs that require `AsRef<str>`, such as `aws_smithy_http::query::fmt_string()`. Changes: - Add `impl AsRef<str>` to `renderUnnamedEnum()` in EnumGenerator.kt - Change `impl<T> From<T> where T: AsRef<str>` to `impl From<&str>` in ClientEnumGenerator.kt to avoid conflicting impl error (E0119) when the type itself implements `AsRef<str>`
Add tests to verify that unnamed enums correctly implement AsRef<str>: - EnumGeneratorTest: Test that unnamed enums can be used with AsRef<str> - ClientEnumGeneratorTest: Test the same for client-generated enums These tests verify the fix that adds impl AsRef<str> to unnamed enums.
aajtodd
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Jan 13, 2026
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Will have to give this more thought.
| writable { | ||
| rustTemplate( | ||
| """ | ||
| impl<T> #{From}<T> for ${context.enumName} where T: #{AsRef}<str> { |
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This would be a breaking change.
Also see #3886
udayprakash
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Jan 15, 2026
Add test cases for enum-related codegen issues: - SpecialCharacterEnum: Enum values containing # characters that conflict with rustTemplate formatting (see PR smithy-lang#4476) - UnnamedEnum: Unnamed enums that need AsRef<str> implementation (see issue smithy-lang#3886, PR smithy-lang#4478) These tests currently fail, demonstrating the bugs that need to be fixed.
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Motivation and Context
Unnamed enums (newtype string wrappers like
pub struct Foo(String)) were missing theAsRef<str>implementation that named enums have. This caused compilation errors when using unnamed enums with APIs that requireAsRef<str>, such asaws_smithy_http::query::fmt_string().Description
impl AsRef<str>torenderUnnamedEnum()in EnumGenerator.kt to match the behavior of named enumsimpl<T> From<T> where T: AsRef<str>toimpl From<&str>in ClientEnumGenerator.kt to avoid conflicting impl error (E0119) when the type itself implementsAsRef<str>Testing
The fix was validated by building Coral-to-Smithy generated Rust clients that use unnamed enums.
Checklist
CHANGELOG.next.tomlif I made changes to the smithy-rs codegen or runtime cratesCHANGELOG.next.tomlif I made changes to the AWS SDK, generated SDK code, or SDK runtime cratesBy submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.