Treat aliases as definitions.

This fixes pr17639.

Before this patch clang would consider

void foo(void) __attribute((alias("__foo")));

a declaration. It now correctly handles it as a definition.

Initial patch by Alp Toker. I added support for variables.

llvm-svn: 193200

3 files changed, 55 insertions, 16 deletions

diff --git a/clang/test/CodeGen/pragma-weak.c b/clang/test/CodeGen/pragma-weak.c
index 40eb525e18f..559be831a55 100644
--- a/clang/test/CodeGen/pragma-weak.c
+++ b/clang/test/CodeGen/pragma-weak.c
@@ -7,8 +7,6 @@
 
 // CHECK-DAG: @both = alias void ()* @__both
 // CHECK-DAG: @both2 = alias void ()* @__both2
-// CHECK-DAG: @both3 = alias weak void ()* @__both3
-// CHECK-DAG: @a3 = alias weak void ()* @__a3
 // CHECK-DAG: @weakvar_alias = alias weak i32* @__weakvar_alias
 // CHECK-DAG: @foo = alias weak void ()* @__foo
 // CHECK-DAG: @foo2 = alias weak void ()* @__foo2
@@ -125,12 +123,6 @@ void both2(void) __attribute((alias("__both2"))); // first, wins
 void __both2(void) {}
 // CHECK-LABEL: define void @__both2()
 
-void __both3(void);
-#pragma weak both3 = __both3 // first, wins
-void both3(void) __attribute((alias("__both3")));
-void __both3(void) {}
-// CHECK-LABEL: define void @__both3()
-
 ///////////// ensure that #pragma weak does not alter existing __attributes()
 
 void __a1(void) __attribute((noinline));
@@ -138,14 +130,6 @@ void __a1(void) __attribute((noinline));
 void __a1(void) {}
 // CHECK: define void @__a1() [[NI:#[0-9]+]]
 
-// attributes introduced BEFORE a combination of #pragma weak and alias()
-// hold...
-void __a3(void) __attribute((noinline));
-#pragma weak a3 = __a3
-void a3(void) __attribute((alias("__a3")));
-void __a3(void) {}
-// CHECK: define void @__a3() [[NI]]
-
 #pragma weak xxx = __xxx
 __attribute((pure,noinline,const)) void __xxx(void) { }
 // CHECK: void @__xxx() [[RN:#[0-9]+]]
diff --git a/clang/test/Sema/alias-redefinition.c b/clang/test/Sema/alias-redefinition.c
new file mode 100644
index 00000000000..6c6ebf80250
--- /dev/null
+++ b/clang/test/Sema/alias-redefinition.c
@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fsyntax-only -verify %s
+
+void f0() {}
+void fun0(void) __attribute((alias("f0")));
+
+void f1() {}
+void fun1() {} // expected-note {{previous definition}}
+void fun1(void) __attribute((alias("f1"))); // expected-error {{redefinition of 'fun1'}}
+
+void f2() {}
+void fun2(void) __attribute((alias("f2"))); // expected-note {{previous definition}}
+void fun2() {} // expected-error {{redefinition of 'fun2'}}
+
+void f3() {}
+void fun3(void) __attribute((alias("f3"))); // expected-note {{previous definition}}
+void fun3(void) __attribute((alias("f3"))); // expected-error {{redefinition of 'fun3'}}
+
+void f4() {}
+void fun4(void) __attribute((alias("f4")));
+void fun4(void);
+
+// FIXME: We should produce a special case error for this.
+void f5() {}
+void __attribute((alias("f5"))) fun5(void) {} // expected-error {{redefinition of 'fun5'}} // expected-note {{previous definition}}
+
+int v1;
+int var1 __attribute((alias("v1"))); // expected-note {{previous definition}}
+int var1 __attribute((alias("v1"))); // expected-error {{redefinition of 'var1'}}
+
+int v2;
+int var2 = 2; // expected-note {{previous definition}}
+int var2 __attribute((alias("v2"))); // expected-error {{redefinition of 'var2'}}
+
+int v3;
+int var3 __attribute((alias("v3"))); // expected-note {{previous definition}}
+int var3 = 2; // expected-error {{redefinition of 'var3'}}
+
+int v4;
+int var4; // expected-note {{previous definition}}
+int var4 __attribute((alias("v4"))); // expected-error {{alias definition of 'var4' after tentative definition}}
+
+int v5;
+int var5 __attribute((alias("v5"))); // expected-note {{previous definition}}
+int var5; // expected-error {{tentative definition of 'var5' after alias definition}}
diff --git a/clang/test/Sema/pragma-weak.c b/clang/test/Sema/pragma-weak.c
new file mode 100644
index 00000000000..c14125eac9f
--- /dev/null
+++ b/clang/test/Sema/pragma-weak.c
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fsyntax-only -verify %s
+
+void __both3(void);
+#pragma weak both3 = __both3 // expected-note {{previous definition}}
+void both3(void) __attribute((alias("__both3"))); // expected-error {{redefinition of 'both3'}}
+void __both3(void) {}
+
+void __a3(void) __attribute((noinline));
+#pragma weak a3 = __a3 // expected-note {{previous definition}}
+void a3(void) __attribute((alias("__a3"))); // expected-error {{redefinition of 'a3'}}
+void __a3(void) {}