[clang] [FMV] Allow multi versioning without default declaration. (PR #85454)

[Alexandros Lamprineas via cfe-commits]

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@@ -70,17 +69,23 @@ int __attribute__((target_version("lse"))) extc(void) { return 1; }
 
 auto __attribute__((target_version("default"))) ret1(void) { return 1; }
 auto __attribute__((target_version("dpb"))) ret2(void) { return 1; }
+// expected-error at -1 {{attribute 'target_version' multiversioned functions do not yet support deduced return types}}
 auto __attribute__((target_version("dpb2"))) ret3(void) -> int { return 1; }
 
 class Cls {
   __attribute__((target_version("rng"))) Cls();
+  // expected-error at -1 {{attribute 'target_version' multiversioned functions do not yet support constructors}}
   __attribute__((target_version("sve-i8mm"))) ~Cls();
+  // expected-error at -1 {{attribute 'target_version' multiversioned functions do not yet support destructors}}
 
   Cls &__attribute__((target_version("f32mm"))) operator=(const Cls &) = default;
+  // expected-error at -1 {{attribute 'target_version' multiversioned functions do not yet support defaulted functions}}
   Cls &__attribute__((target_version("ssbs"))) operator=(Cls &&) = delete;
+  // expected-error at -1 {{attribute 'target_version' multiversioned functions do not yet support deleted functions}}
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labrinea wrote:

Without a default declaration target_version was ignored so these errors wouldn't trigger.

https://github.com/llvm/llvm-project/pull/85454