Update assumption in template diffing about integer template arguments.

Fix for PR22017.  Integer template arguments are automatically bit extended to
the size of the integer type.  In template diffing, evaluated expressions were
not having their results extending, leading to comparing two APSInt's with
different widths.  Apply the proper bit extending when evaluating template
arguments.  This mainly affected bool template arguments.

llvm-svn: 230603

1 files changed, 14 insertions, 6 deletions

diff --git a/clang/lib/AST/ASTDiagnostic.cpp b/clang/lib/AST/ASTDiagnostic.cpp
index f55e0326c44..000588face9 100644
--- a/clang/lib/AST/ASTDiagnostic.cpp
+++ b/clang/lib/AST/ASTDiagnostic.cpp
@@ -1003,9 +1003,11 @@ class TemplateDiff {
       Tree.SetDefault(FromIter.isEnd() && FromExpr, ToIter.isEnd() && ToExpr);
       if (FromDefaultNonTypeDecl->getType()->isIntegralOrEnumerationType()) {
         if (FromExpr)
-          HasFromInt = GetInt(Context, FromIter, FromExpr, FromInt);
+          HasFromInt = GetInt(Context, FromIter, FromExpr, FromInt,
+                              FromDefaultNonTypeDecl->getType());
         if (ToExpr)
-          HasToInt = GetInt(Context, ToIter, ToExpr, ToInt);
+          HasToInt = GetInt(Context, ToIter, ToExpr, ToInt,
+                            ToDefaultNonTypeDecl->getType());
       }
       if (HasFromInt && HasToInt) {
         Tree.SetNode(FromInt, ToInt, HasFromInt, HasToInt);
@@ -1026,9 +1028,11 @@ class TemplateDiff {
 
     if (HasFromInt || HasToInt) {
       if (!HasFromInt && FromExpr)
-        HasFromInt = GetInt(Context, FromIter, FromExpr, FromInt);
+        HasFromInt = GetInt(Context, FromIter, FromExpr, FromInt,
+                            FromDefaultNonTypeDecl->getType());
       if (!HasToInt && ToExpr)
-        HasToInt = GetInt(Context, ToIter, ToExpr, ToInt);
+        HasToInt = GetInt(Context, ToIter, ToExpr, ToInt,
+                          ToDefaultNonTypeDecl->getType());
       Tree.SetNode(FromInt, ToInt, HasFromInt, HasToInt);
       if (HasFromInt && HasToInt) {
         Tree.SetSame(FromInt == ToInt);
@@ -1210,9 +1214,11 @@ class TemplateDiff {
   }
 
   /// GetInt - Retrieves the template integer argument, including evaluating
-  /// default arguments.
+  /// default arguments.  If the value comes from an expression, extend the
+  /// APSInt to size of IntegerType to match the behavior in
+  /// Sema::CheckTemplateArgument
   static bool GetInt(ASTContext &Context, const TSTiterator &Iter,
-                     Expr *ArgExpr, llvm::APSInt &Int) {
+                     Expr *ArgExpr, llvm::APSInt &Int, QualType IntegerType) {
     // Default, value-depenedent expressions require fetching
     // from the desugared TemplateArgument, otherwise expression needs to
     // be evaluatable.
@@ -1224,12 +1230,14 @@ class TemplateDiff {
         case TemplateArgument::Expression:
           ArgExpr = Iter.getDesugar().getAsExpr();
           Int = ArgExpr->EvaluateKnownConstInt(Context);
+          Int = Int.extOrTrunc(Context.getTypeSize(IntegerType));
           return true;
         default:
           llvm_unreachable("Unexpected template argument kind");
       }
     } else if (ArgExpr->isEvaluatable(Context)) {
       Int = ArgExpr->EvaluateKnownConstInt(Context);
+      Int = Int.extOrTrunc(Context.getTypeSize(IntegerType));
       return true;
     }