From: David Majnemer <david.majnemer@gmail.com>
Date: Wed, 9 Jul 2014 17:15:52 +0000 (+0000)
Subject: Sema: Allow aliases to have incomplete type
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=48f80aa9abf55d5a2e195e2e8a58fb6e12f3887c;p=clang

Sema: Allow aliases to have incomplete type

gcc supports this behavior and it is pervasively used inside the Linux
kernel.

Note that both gcc and clang will reject code that attempts to do this
in a C++ language mode.

This fixes PR17998.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@212631 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 82d28fa082..13a77f15eb 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -8897,11 +8897,13 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl,
     if (Var->isInvalidDecl())
       return;
 
-    if (RequireCompleteType(Var->getLocation(), 
-                            Context.getBaseElementType(Type),
-                            diag::err_typecheck_decl_incomplete_type)) {
-      Var->setInvalidDecl();
-      return;
+    if (!Var->hasAttr<AliasAttr>()) {
+      if (RequireCompleteType(Var->getLocation(),
+                              Context.getBaseElementType(Type),
+                              diag::err_typecheck_decl_incomplete_type)) {
+        Var->setInvalidDecl();
+        return;
+      }
     }
 
     // The variable can not have an abstract class type.
diff --git a/test/Sema/attr-alias-elf.c b/test/Sema/attr-alias-elf.c
index 04d13924ac..f14514dccd 100644
--- a/test/Sema/attr-alias-elf.c
+++ b/test/Sema/attr-alias-elf.c
@@ -64,3 +64,6 @@ void test3_foo() __attribute__((alias("test3_bar")));
 __attribute__((section("test"))) void test4_bar() { }
 void test4_foo() __attribute__((section("test")));
 void test4_foo() __attribute__((alias("test4_bar")));
+
+int test5_bar = 0;
+extern struct incomplete_type test5_foo __attribute__((alias("test5_bar")));