[6.2]Fix crash in macros caused by mixing prebuilts and source. #9261
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There is an issue when a macro that uses prebuilts uses a library that also depends on the swift-syntax library. This is commonly used to share utility code between macros. However, we currently can't tell whether the library will only be built for the host so it can not take advantage of the prebuilts. When a macro which is using prebuilts uses that library, we are seeing crashes in the macro caused when the library and the swift-syntax it uses is built for debug which is then linked with the macro which uses the swift-syntas prebuilts which are built for release. For now, this change turns off the prebuilts for macros that use such a library to avoid the crash. We'll investigate making the use of prebuilts conditional on the build settings in a future release. To be able to implement this change, we need to be able to detect the downstream swift-syntax dependency. We move the insertion of the settings for the prebuilts from Module creation time until after the ResolvedModuleBuilder is created so that we can make the changes there before the final ResolvedModules are created.
dschaefer2
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Addressing #9196 |
dschaefer2
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Oct 17, 2025
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@swift-ci please test |
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@swift-ci please test windows |
rconnell9
approved these changes
Oct 20, 2025
dschaefer2
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Oct 20, 2025
…#9261) There is an issue when a macro that uses prebuilts uses a library that also depends on the swift-syntax library. This is commonly used to share utility code between macros. However, we currently can't tell whether the library will only be built for the host so it can not take advantage of the prebuilts. When a macro which is using prebuilts uses that library, we are seeing crashes in the macro caused when the library and the swift-syntax it uses is built for debug which is then linked with the macro which uses the swift-syntax prebuilts which are built for release. For now, this change turns off the prebuilts for macros that use such a library to avoid the crash. We'll investigate making the use of prebuilts conditional on the build settings in a future release. To be able to implement this change, we need to be able to detect the downstream swift-syntax dependency. We move the insertion of the settings for the prebuilts from Module creation time until after the ResolvedModuleBuilder is created so that we can make the changes there before the final ResolvedModules are created.
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There is an issue when a macro that uses prebuilts uses a library that also depends on the swift-syntax library. This is commonly used to share utility code between macros.
However, we currently can't tell whether the library will only be built for the host so it can not take advantage of the prebuilts. When a macro which is using prebuilts uses that library, we are seeing crashes in the macro caused when the library and the swift-syntax it uses is built for debug which is then linked with the macro which uses the swift-syntax prebuilts which are built for release.
For now, this change turns off the prebuilts for macros that use such a library to avoid the crash. We'll investigate making the use of prebuilts conditional on the build settings in a future release.
To be able to implement this change, we need to be able to detect the downstream swift-syntax dependency. We move the insertion of the settings for the prebuilts from Module creation time until after the ResolvedModuleBuilder is created so that we can make the changes there before the final ResolvedModules are created.