Check for redefinitions in MergeVarDecl. This finds redefinitions of globals without an initializer in C++ and thus fixes PR5451.

llvm-svn: 95098

1 files changed, 21 insertions, 0 deletions

diff --git a/clang/test/CXX/basic/basic.def.odr/p1-var.cpp b/clang/test/CXX/basic/basic.def.odr/p1-var.cpp
new file mode 100644
index 00000000000..892f546ee54
--- /dev/null
+++ b/clang/test/CXX/basic/basic.def.odr/p1-var.cpp
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// C++ [basic.def.odr]p1:
+//   No translation unit shall contain more than one definition of any
+//   variable, [...].
+
+// Bad: in C++, these are both definitions. None of that C99 tentative stuff.
+int i; // expected-note {{previous}}
+int i; // expected-error {{redefinition}}
+
+// OK: decl + def
+extern int j;
+int j;
+
+// OK: def + decl
+int k;
+extern int k;
+
+// Bad. The important thing here is that we don't emit the diagnostic twice.
+int l = 1; // expected-note {{previous}}
+int l = 2; // expected-error {{redefinition}}