Merge function types in C.

Among other differences, GCC accepts

  typedef int IA[];
  typedef int A10[10];
  static A10 *f(void);
  static IA  *f(void);
  void g(void) {
    (void)sizeof(*f());
  }

but clang used to reject it with:

  invalid application of 'sizeof' to an incomplete type 'IA' (aka 'int []')

The intention of c99's 6.2.7 seems to be that we should use the composite type
and accept as gcc does.

Doing the type merging required some extra fixes:
  * Use the type from the function type in initializations, even if an parameter
    is available.
  * Fix the merging of the noreturn attribute in function types.
  * Make CodeGen  handle the fact that an parameter type can be different from
    the corresponding type in the function type.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168895 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 1 deletions

diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 54ccb86a03..3b39d2e616 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -1232,7 +1232,15 @@ void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
 
         if (isPromoted)
           V = emitArgumentDemotion(*this, Arg, V);
-        
+
+        // Because of merging of function types from multiple decls it is
+        // possible for the type of an argument to not match the corresponding
+        // type in the function type. Since we are codegening the callee
+        // in here, add a cast to the argument type.
+        llvm::Type *LTy = ConvertType(Arg->getType());
+        if (V->getType() != LTy)
+          V = Builder.CreateBitCast(V, LTy);
+
         EmitParmDecl(*Arg, V, ArgNo);
         break;
       }