[ODRHash] Support ODR violation detection in functions.

Extend the hashing to functions, which allows detection of function definition
mismatches across modules.  This is a re-commit of r320230.

llvm-svn: 321395

1 files changed, 20 insertions, 0 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index ee15a4d2b4f..629037b1755 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -26,6 +26,7 @@
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExternalASTSource.h"
+#include "clang/AST/ODRHash.h"
 #include "clang/AST/PrettyPrinter.h"
 #include "clang/AST/Redeclarable.h"
 #include "clang/AST/Stmt.h"
@@ -3604,6 +3605,25 @@ unsigned FunctionDecl::getMemoryFunctionKind() const {
   return 0;
 }
 
+unsigned FunctionDecl::getODRHash() {
+  if (HasODRHash)
+    return ODRHash;
+
+  if (FunctionDecl *Definition = getDefinition()) {
+    if (Definition != this) {
+      HasODRHash = true;
+      ODRHash = Definition->getODRHash();
+      return ODRHash;
+    }
+  }
+
+  class ODRHash Hash;
+  Hash.AddFunctionDecl(this);
+  HasODRHash = true;
+  ODRHash = Hash.CalculateHash();
+  return ODRHash;
+}
+
 //===----------------------------------------------------------------------===//
 // FieldDecl Implementation
 //===----------------------------------------------------------------------===//