Add default argument values

Author: OCHyams

clang/lib/AST/ExprConstant.cpp

@@ -12760,7 +12760,7 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
         if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free ||
             Size == CharUnits::One() ||
             E->getArg(1)->isNullPointerConstant(Info.Ctx,
-                                                Expr::NPC_NeverValueDependent))
+                                                Expr::NPC_ValueDependentIsNull))
           // OK, we will inline appropriately-aligned operations of this size,
           // and _Atomic(T) is appropriately-aligned.
           return Success(1, E);

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -1339,24 +1339,51 @@ llvm::DIType *CGDebugInfo::CreateType(const TemplateSpecializationType *Ty,
     // being substituted into a parameter pack. We can find out if that's
     // the case now by inspecting the TypeAliasTemplateDecl template
     // parameters. Insert Ty's template args into SpecArgs, bundling args
-    // passed to a parameter pack into a TemplateArgument::Pack.
+    // passed to a parameter pack into a TemplateArgument::Pack. It also
+    // doesn't know the value of any defaulted args, so collect those now
+    // too.
     SmallVector<TemplateArgument> SpecArgs;
     {
       ArrayRef SubstArgs = Ty->template_arguments();
-      for (const NamedDecl *P : TD->getTemplateParameters()->asArray()) {
-        if (P->isParameterPack()) {
+      for (const NamedDecl *Param : TD->getTemplateParameters()->asArray()) {
+        // If Param is a parameter pack, pack the remaining arguments.
+        if (Param->isParameterPack()) {
           SpecArgs.push_back(TemplateArgument(SubstArgs));
           break;
         }
-        // Skip defaulted args.
-        if (SubstArgs.empty()) {
-          // If SubstArgs is now empty (we're taking from it each iteration) and
-          // this template parameter isn't a pack, then that should mean we're
-          // using default values for the remaining template parameters.
+
+        // Take the next argument.
+        if (!SubstArgs.empty()) {
+          SpecArgs.push_back(SubstArgs.front());
+          SubstArgs = SubstArgs.drop_front();
+          continue;
+        }
+
+        // If SubstArgs is now empty (we're taking from it each iteration) and
+        // this template parameter isn't a pack, then that should mean we're
+        // using default values for the remaining template parameters. Push the
+        // default value for each parameter.
+        if (auto *P = dyn_cast<TemplateTypeParmDecl>(Param)) {
+          assert(P->hasDefaultArgument() &&
+                 "expected defaulted template type parameter");
+          SpecArgs.push_back(TemplateArgument(P->getDefaultArgument(),
+                                              /*IsNullPtr=*/false,
+                                              /*IsDefaulted=*/true));
+        } else if (auto *P = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
+          assert(P->hasDefaultArgument() &&
+                 "expected defaulted template non-type parameter");
+          SpecArgs.push_back(TemplateArgument(P->getDefaultArgument(),
+                                              /*IsDefaulted=*/true));
+        } else if (auto *P = dyn_cast<TemplateTemplateParmDecl>(Param)) {
+          assert(P->hasDefaultArgument() &&
+                 "expected defaulted template template parameter");
+          SpecArgs.push_back(TemplateArgument(
+              P->getDefaultArgument().getArgument().getAsTemplate(),
+              /*IsDefaulted=*/true));
+        } else {
+          llvm_unreachable("Unexpected template parameter kind");
           break;
         }
-        SpecArgs.push_back(SubstArgs.front());
-        SubstArgs = SubstArgs.drop_front();
       }
     }
     TemplateArgs Args = {TD->getTemplateParameters(), SpecArgs};

clang/test/CodeGenCXX/defaulted-template-alias.cpp

@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 -triple x86_64-unk-unk -o - -emit-llvm -debug-info-kind=standalone -gtemplate-alias %s -gsimple-template-names=simple \
+// RUN: | FileCheck %s
+
+//// Check that -gtemplate-alias causes DW_TAG_template_alias emission for
+//// template aliases with default parameter values. See template-alias.cpp for
+////  more template alias tests.
+
+template<typename T>
+struct X {
+  char m;
+};
+
+template<typename T>
+struct Y {
+  char n;
+};
+
+template <typename NonDefault, template <typename C> class T = Y, int I = 5, typename... Ts>
+using A = X<NonDefault>;
+
+//// We should be able to emit type alias metadata which describes all the
+//// values, including the defaulted parameters and empty parameter pack.
+A<int> a;
+
+// CHECK: !DIDerivedType(tag: DW_TAG_template_alias, name: "A", file: ![[#]], line: [[#]], baseType: ![[baseType:[0-9]+]], extraData: ![[extraData:[0-9]+]])
+// CHECK: ![[baseType]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "X",
+// CHECK: ![[int:[0-9]+]] = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+// CHECK: ![[extraData]] = !{![[NonDefault:[0-9]+]], ![[T:[0-9]+]], ![[I:[0-9]+]], ![[Ts:[0-9]+]]}
+// CHECK: ![[NonDefault]] = !DITemplateTypeParameter(name: "NonDefault", type: ![[int]])
+// CHECK: ![[T]] = !DITemplateValueParameter(tag: DW_TAG_GNU_template_template_param, name: "T", defaulted: true, value: !"Y")
+// CHECK: ![[I]] = !DITemplateValueParameter(name: "I", type: ![[int]], defaulted: true, value: i32 5)
+// CHECK: ![[Ts]] = !DITemplateValueParameter(tag: DW_TAG_GNU_template_parameter_pack, name: "Ts", value: ![[types:[0-9]+]])
+// CHECK: ![[types]] = !{}