PR2044: reject declarations of functions returning variably modified

types.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@71941 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 12 insertions, 0 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 1ed063ab40..077658c624 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2344,6 +2344,13 @@ void Sema::CheckFunctionDeclaration(FunctionDecl *NewFD, NamedDecl *&PrevDecl,
   if (NewFD->isInvalidDecl())
     return;
 
+  if (NewFD->getResultType()->isVariablyModifiedType()) {
+    // Functions returning a variably modified type violate C99 6.7.5.2p2
+    // because all functions have linkage.
+    Diag(NewFD->getLocation(), diag::err_vm_func_decl);
+    return NewFD->setInvalidDecl();
+  }
+
   // Semantic checking for this function declaration (in isolation).
   if (getLangOptions().CPlusPlus) {
     // C++-specific checks.
diff --git a/test/Sema/vla.c b/test/Sema/vla.c
index b4839143bf..674547297a 100644
--- a/test/Sema/vla.c
+++ b/test/Sema/vla.c
@@ -46,3 +46,8 @@ static const unsigned array[((2 * (int)((((4) / 2) + 1.0/3.0) * (4) - 1e-8)) + 1
 
 int a[*]; // expected-error {{star modifier used outside of function prototype}}
 int f4(int a[*][*]);
+
+// PR2044
+int pr2044(int b) {int (*c(void))[b];**c() = 2;} // expected-error {{variably modified type}}
+int pr2044b;
+int (*pr2044c(void))[pr2044b]; // expected-error {{variably modified type}}