Add a new warning -Wmissing-variable-declarations, to warn about variables

defined without a previous declaration.  This is similar to
-Wmissing-prototypes, but for variables instead of functions.

Patch by Ed Schouten.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@166498 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 162c50b7fe..19442b98c1 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -7148,6 +7148,17 @@ void Sema::CheckCompleteVariableDeclaration(VarDecl *var) {
     }
   }
 
+  if (var->isThisDeclarationADefinition() &&
+      var->getLinkage() == ExternalLinkage) {
+    // Find a previous declaration that's not a definition.
+    VarDecl *prev = var->getPreviousDecl();
+    while (prev && prev->isThisDeclarationADefinition())
+      prev = prev->getPreviousDecl();
+
+    if (!prev)
+      Diag(var->getLocation(), diag::warn_missing_variable_declarations) << var;
+  }
+
   // All the following checks are C++ only.
   if (!getLangOpts().CPlusPlus) return;