Modified version

Author: MillePlateaux

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -3161,7 +3161,7 @@ def err_musttail_member_mismatch : Error<
 def note_musttail_callee_defined_here : Note<"%0 declared here">;
 def note_tail_call_required : Note<"tail call required by %0 attribute here">;
 def err_musttail_mismatch : Error<
-  "cannot perform a tail call to function %select{| %1}0 because its signature "
+  "cannot perform a tail call to function%select{| %1}0 because its signature "
   "is incompatible with the calling function">;
 def note_musttail_mismatch : Note<
     "target function "

clang/lib/Sema/SemaStmt.cpp

@@ -719,7 +719,7 @@ bool Sema::checkMustTailAttr(const Stmt *St, const Attr &MTA) {
 
   if (const FunctionDecl *CalleeDecl = CE->getDirectCallee();
       CalleeDecl && CalleeDecl->hasAttr<NotTailCalledAttr>()) {
-    Diag(St->getBeginLoc(), diag::err_musttail_mismatch) << &MTA;
+    Diag(St->getBeginLoc(), diag::err_musttail_mismatch) << CalleeDecl;
     return false;
   }
 

clang/test/Sema/attr-musttail.cpp

@@ -7,7 +7,7 @@ int __attribute__((not_tail_called)) foo1(int a) {
 
 int foo2(int a) {
     [[clang::musttail]] 
-    return foo1(a);  // expected-error{{cannot perform a tail call to function 'musttail' because its signature is incompatible with the calling function}}
+    return foo1(a);  // expected-error{{cannot perform a tail call to function'foo1' because its signature is incompatible with the calling function}}
 }
 
 int main() {