[clang] [Clang][CodeGen] Report when an alias points to an incompatible target (PR #192397)

[Anton Korobeynikov via cfe-commits]

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@@ -59,7 +59,7 @@ extern void f1(void) __attribute((alias("f0")));
 static inline int foo1() { return 0; }
 // CHECKBASIC-LABEL: define internal i32 @foo1()
 int foo() __attribute__((alias("foo1")));
-int bar() __attribute__((alias("bar1")));
+extern int bar __attribute__((alias("bar1")));
 
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asl wrote:

`bar` was a function, but not function anymore. I guess exactly it started to be rejected after the PR (since `bar1` is a variable).

https://github.com/llvm/llvm-project/pull/192397