[clang] [clang] Redeclarations should inherit all unique SwiftAttrs (PR #217187)

[John Hui via cfe-commits]

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@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -ast-dump -ast-dump-filter=two_on_first %s \
+// RUN:   | FileCheck --check-prefix=TWO --implicit-check-not=SwiftAttrAttr %s
+// RUN: %clang_cc1 -ast-dump -ast-dump-filter=split %s \
+// RUN:   | FileCheck --check-prefix=SPLIT --implicit-check-not=SwiftAttrAttr %s
+// RUN: %clang_cc1 -ast-dump -ast-dump-filter=dedup %s \
+// RUN:   | FileCheck --check-prefix=DEDUP --implicit-check-not=SwiftAttrAttr %s
+
+// 'swift_attr' is a bag of independent annotations identified by its string
+// argument, so a redeclaration inherits all of them, not just the first.
+
+__attribute__((swift_attr("@a"))) __attribute__((swift_attr("@b")))
+void two_on_first(void);
+void two_on_first(void);
+
+// TWO:      FunctionDecl {{.*}} two_on_first
+// TWO-NEXT:   SwiftAttrAttr {{.*}} "@a"
+// TWO-NEXT:   SwiftAttrAttr {{.*}} "@b"
+// TWO:      FunctionDecl {{.*}} prev {{.*}} two_on_first
+// TWO-NEXT:   SwiftAttrAttr {{.*}} Inherited "@a"
+// TWO-NEXT:   SwiftAttrAttr {{.*}} Inherited "@b"
+
+// A 'swift_attr' on the redeclaration must not suppress inheriting the
+// different ones from the previous declaration.
+__attribute__((swift_attr("@x"))) void split(void);
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j-hui wrote:

Perhaps this should have two attributes, to make sure both are inherited?

https://github.com/llvm/llvm-project/pull/217187