[clang] 09d4021 - Fix compatibility for __builtin_stdarg_start

[Joerg Sonnenberger via cfe-commits]

Author: Joerg Sonnenberger
Date: 2020-03-28T23:24:13+01:00
New Revision: 09d402185394fdbf1f60233a7f42a4a1108c2cd3

URL: https://github.com/llvm/llvm-project/commit/09d402185394fdbf1f60233a7f42a4a1108c2cd3
DIFF: https://github.com/llvm/llvm-project/commit/09d402185394fdbf1f60233a7f42a4a1108c2cd3.diff

LOG: Fix compatibility for __builtin_stdarg_start

The __builtin_stdarg_start is the legacy spelling of __builtin_va_start.
It should behave exactly the same, but for the last 9 years it would
behave subtly different for diagnostics. Follow the change from
29ad95b23217 to require custom type checking.

Added: 
    

Modified: 
    clang/include/clang/Basic/Builtins.def
    clang/test/SemaCXX/vararg-non-pod.cpp

Removed: 
    


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diff  --git a/clang/include/clang/Basic/Builtins.def b/clang/include/clang/Basic/Builtins.def
index 85f775a7cad8..9613f312d52d 100644
--- a/clang/include/clang/Basic/Builtins.def
+++ b/clang/include/clang/Basic/Builtins.def
@@ -472,7 +472,7 @@ BUILTIN(__builtin___NSStringMakeConstantString, "FC*cC*", "nc")
 BUILTIN(__builtin_va_start, "vA.", "nt")
 BUILTIN(__builtin_va_end, "vA", "n")
 BUILTIN(__builtin_va_copy, "vAA", "n")
-BUILTIN(__builtin_stdarg_start, "vA.", "n")
+BUILTIN(__builtin_stdarg_start, "vA.", "nt")
 BUILTIN(__builtin_assume_aligned, "v*vC*z.", "nc")
 BUILTIN(__builtin_bcmp, "ivC*vC*z", "Fn")
 BUILTIN(__builtin_bcopy, "vv*v*z", "n")

diff  --git a/clang/test/SemaCXX/vararg-non-pod.cpp b/clang/test/SemaCXX/vararg-non-pod.cpp
index 1b7f3b68dc97..a1bbe748d12d 100644
--- a/clang/test/SemaCXX/vararg-non-pod.cpp
+++ b/clang/test/SemaCXX/vararg-non-pod.cpp
@@ -164,6 +164,13 @@ void t6(Foo somearg, ... ) {
   __builtin_va_start(list, somearg);
 }
 
+// __builtin_stdarg_start is a compatibility alias for __builtin_va_start,
+// it should behave the same
+void t6b(Foo somearg, ... ) {
+  __builtin_va_list list;
+  __builtin_stdarg_start(list, somearg); // second argument to 'va_start' is not the last named parameter [-Wvarargs]
+}
+
 void t7(int n, ...) {
   __builtin_va_list list;
   __builtin_va_start(list, n);