Sema: Stop checking @main if no decl synthesized. #36529
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When requestifying the synthesis of the main function for the type annotated @main via SynthesizeMainFunctionRequest, what were previously were bailouts from AttributeChecker::visitMainTypeAttr had to become returns of nullptr from SynthesizeMainFunctionRequest::evaluate. Consequently, AttributeChecker::visitMainTypeAttr must check whether synthesis actually succeeded before proceeding to to register the main decl for a file. In simple cases, this happened to work because SourceFile::registerMainDecl would return early if the decl being registered was the same as the already registered main decl and in particular if the decl being registered was nullptr and the previously registered one was nullptr as well. When, however, there are multiple types annotated @main, if a function is successfully synthesized for one type but synthesis fails for the second, an attempt will be made to register nullptr as the main decl and will move past the check at the beginning of SourceFile::registerMainDecl, resulting in a crash. Here, we bail from AttributeChecker::visitMainTypeAttr if function synthesis fails and add an assert to SourceFile::registerMainDecl that the provided decl is non-null. rdar://75547146
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@swift-ci please test |
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When requestifying the synthesis of the main function for the type annotated @main via SynthesizeMainFunctionRequest, what previously were bailouts from AttributeChecker::visitMainTypeAttr had to become returns of nullptr from SynthesizeMainFunctionRequest::evaluate. Consequently, AttributeChecker::visitMainTypeAttr must check whether synthesis actually succeeded before proceeding to to register the main decl for a file.
In simple illegal cases, not checking happened to work because SourceFile::registerMainDecl would return early if the decl being registered was the same as the already registered main decl and in particular if the decl being registered was nullptr and the previously registered one was nullptr as well. When, however, there are multiple types annotated @main, if a function is successfully synthesized for one type but synthesis fails for the second, an attempt will be made to register nullptr as the main decl and will move past the check at the beginning of SourceFile::registerMainDecl, resulting in a crash.
Here, we bail from AttributeChecker::visitMainTypeAttr if function synthesis fails and add an assert to SourceFile::registerMainDecl that the provided decl is non-null.
rdar://75547146