PR32010: Fix template argument depth mixup when forming implicit constructor

template deduction guides for class template argument deduction.

Ensure that we have a local instantiation scope for tracking the instantiated
parameters. Additionally, unusually, we're substituting at depth 1 and leaving
depth 0 alone; make sure that we don't reduce template parameter depth by 2 for
inner parameters in the process. (This is probably also broken for alias
templates in the case where they're expanded within a dependent context, but
this patch doesn't fix that.)

llvm-svn: 295696

3 files changed, 44 insertions, 36 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 4b4a47d63c8..ad7b9e54f90 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1442,6 +1442,8 @@ struct ConvertConstructorToDeductionGuideTransform {
                                   CXXConstructorDecl *CD) {
     SmallVector<TemplateArgument, 16> SubstArgs;
 
+    LocalInstantiationScope Scope(SemaRef);
+
     // C++ [over.match.class.deduct]p1:
     // -- For each constructor of the class template designated by the
     //    template-name, a function template with the following properties:
@@ -1463,7 +1465,7 @@ struct ConvertConstructorToDeductionGuideTransform {
       for (NamedDecl *Param : *InnerParams) {
         MultiLevelTemplateArgumentList Args;
         Args.addOuterTemplateArguments(SubstArgs);
-        Args.addOuterTemplateArguments(None);
+        Args.addOuterRetainedLevel();
         NamedDecl *NewParam = transformTemplateParameter(Param, Args);
         if (!NewParam)
           return nullptr;
@@ -1483,7 +1485,7 @@ struct ConvertConstructorToDeductionGuideTransform {
     MultiLevelTemplateArgumentList Args;
     if (FTD) {
       Args.addOuterTemplateArguments(SubstArgs);
-      Args.addOuterTemplateArguments(None);
+      Args.addOuterRetainedLevel();
     }
 
     FunctionProtoTypeLoc FPTL = CD->getTypeSourceInfo()->getTypeLoc()
@@ -1555,6 +1557,8 @@ private:
         if (InstantiatedDefaultArg)
           NewTTP->setDefaultArgument(InstantiatedDefaultArg);
       }
+      SemaRef.CurrentInstantiationScope->InstantiatedLocal(TemplateParam,
+                                                           NewTTP);
       return NewTTP;
     }
 
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 723a6c0e4de..f7535e6d242 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1121,6 +1121,23 @@ TemplateInstantiator::TransformTemplateParmRefExpr(DeclRefExpr *E,
     return E;
 
   TemplateArgument Arg = TemplateArgs(NTTP->getDepth(), NTTP->getPosition());
+
+  if (TemplateArgs.getNumLevels() != TemplateArgs.getNumSubstitutedLevels()) {
+    // We're performing a partial substitution, so the substituted argument
+    // could be dependent. As a result we can't create a SubstNonType*Expr
+    // node now, since that represents a fully-substituted argument.
+    // FIXME: We should have some AST representation for this.
+    if (Arg.getKind() == TemplateArgument::Pack) {
+      // FIXME: This won't work for alias templates.
+      assert(Arg.pack_size() == 1 && Arg.pack_begin()->isPackExpansion() &&
+             "unexpected pack arguments in partial substitution");
+      Arg = Arg.pack_begin()->getPackExpansionPattern();
+    }
+    assert(Arg.getKind() == TemplateArgument::Expression &&
+           "unexpected nontype template argument kind in partial substitution");
+    return Arg.getAsExpr();
+  }
+
   if (NTTP->isParameterPack()) {
     assert(Arg.getKind() == TemplateArgument::Pack && 
            "Missing argument pack");
@@ -1429,12 +1446,9 @@ TemplateInstantiator::TransformTemplateTypeParmType(TypeLocBuilder &TLB,
     NewTTPDecl = cast_or_null<TemplateTypeParmDecl>(
                                   TransformDecl(TL.getNameLoc(), OldTTPDecl));
 
-  QualType Result
-    = getSema().Context.getTemplateTypeParmType(T->getDepth()
-                                                 - TemplateArgs.getNumLevels(),
-                                                T->getIndex(),
-                                                T->isParameterPack(),
-                                                NewTTPDecl);
+  QualType Result = getSema().Context.getTemplateTypeParmType(
+      T->getDepth() - TemplateArgs.getNumSubstitutedLevels(), T->getIndex(),
+      T->isParameterPack(), NewTTPDecl);
   TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
   return Result;
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 63c10c0c712..b285d4f3814 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2074,13 +2074,10 @@ Decl *TemplateDeclInstantiator::VisitTemplateTypeParmDecl(
   // TODO: don't always clone when decls are refcounted.
   assert(D->getTypeForDecl()->isTemplateTypeParmType());
 
-  TemplateTypeParmDecl *Inst =
-    TemplateTypeParmDecl::Create(SemaRef.Context, Owner,
-                                 D->getLocStart(), D->getLocation(),
-                                 D->getDepth() - TemplateArgs.getNumLevels(),
-                                 D->getIndex(), D->getIdentifier(),
-                                 D->wasDeclaredWithTypename(),
-                                 D->isParameterPack());
+  TemplateTypeParmDecl *Inst = TemplateTypeParmDecl::Create(
+      SemaRef.Context, Owner, D->getLocStart(), D->getLocation(),
+      D->getDepth() - TemplateArgs.getNumSubstitutedLevels(), D->getIndex(),
+      D->getIdentifier(), D->wasDeclaredWithTypename(), D->isParameterPack());
   Inst->setAccess(AS_public);
 
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
@@ -2218,17 +2215,14 @@ Decl *TemplateDeclInstantiator::VisitNonTypeTemplateParmDecl(
   if (IsExpandedParameterPack)
     Param = NonTypeTemplateParmDecl::Create(
         SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
-        D->getDepth() - TemplateArgs.getNumLevels(), D->getPosition(),
-        D->getIdentifier(), T, DI, ExpandedParameterPackTypes,
+        D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
+        D->getPosition(), D->getIdentifier(), T, DI, ExpandedParameterPackTypes,
         ExpandedParameterPackTypesAsWritten);
   else
-    Param = NonTypeTemplateParmDecl::Create(SemaRef.Context, Owner,
-                                            D->getInnerLocStart(),
-                                            D->getLocation(),
-                                    D->getDepth() - TemplateArgs.getNumLevels(),
-                                            D->getPosition(),
-                                            D->getIdentifier(), T,
-                                            D->isParameterPack(), DI);
+    Param = NonTypeTemplateParmDecl::Create(
+        SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
+        D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
+        D->getPosition(), D->getIdentifier(), T, D->isParameterPack(), DI);
 
   Param->setAccess(AS_public);
   if (Invalid)
@@ -2349,19 +2343,15 @@ TemplateDeclInstantiator::VisitTemplateTemplateParmDecl(
   // Build the template template parameter.
   TemplateTemplateParmDecl *Param;
   if (IsExpandedParameterPack)
-    Param = TemplateTemplateParmDecl::Create(SemaRef.Context, Owner,
-                                             D->getLocation(),
-                                   D->getDepth() - TemplateArgs.getNumLevels(),
-                                             D->getPosition(),
-                                             D->getIdentifier(), InstParams,
-                                             ExpandedParams);
+    Param = TemplateTemplateParmDecl::Create(
+        SemaRef.Context, Owner, D->getLocation(),
+        D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
+        D->getPosition(), D->getIdentifier(), InstParams, ExpandedParams);
   else
-    Param = TemplateTemplateParmDecl::Create(SemaRef.Context, Owner,
-                                             D->getLocation(),
-                                   D->getDepth() - TemplateArgs.getNumLevels(),
-                                             D->getPosition(),
-                                             D->isParameterPack(),
-                                             D->getIdentifier(), InstParams);
+    Param = TemplateTemplateParmDecl::Create(
+        SemaRef.Context, Owner, D->getLocation(),
+        D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
+        D->getPosition(), D->isParameterPack(), D->getIdentifier(), InstParams);
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
     NestedNameSpecifierLoc QualifierLoc =
         D->getDefaultArgument().getTemplateQualifierLoc();