Sema: Subst type default template args earlier

Summary:
We would not perform substitution at an appropriate point, allowing strange
results to appear. We would accepts things that we shouldn't or mangle things incorrectly.  Note that this hasn't fixed the other cases like
template-template parameters or non-type template parameters.

Reviewers: doug.gregor, rjmccall, rsmith

Reviewed By: rsmith

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1507

llvm-svn: 189540

6 files changed, 151 insertions, 44 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 4268aa24e36..426b13cfaf4 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -2976,22 +2976,25 @@ SubstDefaultTemplateArgument(Sema &SemaRef,
   // If the argument type is dependent, instantiate it now based
   // on the previously-computed template arguments.
   if (ArgType->getType()->isDependentType()) {
-    TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
-                                      Converted.data(), Converted.size());
-
-    MultiLevelTemplateArgumentList AllTemplateArgs
-      = SemaRef.getTemplateInstantiationArgs(Template, &TemplateArgs);
-
     Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
                                      Template, Converted,
                                      SourceRange(TemplateLoc, RAngleLoc));
     if (Inst)
       return 0;
 
+    TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
+                                      Converted.data(), Converted.size());
+
+    // Only substitute for the innermost template argument list.
+    MultiLevelTemplateArgumentList TemplateArgLists;
+    TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
+    for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
+      TemplateArgLists.addOuterTemplateArguments(None);
+
     Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
-    ArgType = SemaRef.SubstType(ArgType, AllTemplateArgs,
-                                Param->getDefaultArgumentLoc(),
-                                Param->getDeclName());
+    ArgType =
+        SemaRef.SubstType(ArgType, TemplateArgLists,
+                          Param->getDefaultArgumentLoc(), Param->getDeclName());
   }
 
   return ArgType;
@@ -3026,21 +3029,24 @@ SubstDefaultTemplateArgument(Sema &SemaRef,
                              SourceLocation RAngleLoc,
                              NonTypeTemplateParmDecl *Param,
                         SmallVectorImpl<TemplateArgument> &Converted) {
-  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
-                                    Converted.data(), Converted.size());
-
-  MultiLevelTemplateArgumentList AllTemplateArgs
-    = SemaRef.getTemplateInstantiationArgs(Template, &TemplateArgs);
-
   Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
                                    Template, Converted,
                                    SourceRange(TemplateLoc, RAngleLoc));
   if (Inst)
     return ExprError();
 
+  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
+                                    Converted.data(), Converted.size());
+
+  // Only substitute for the innermost template argument list.
+  MultiLevelTemplateArgumentList TemplateArgLists;
+  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
+  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
+    TemplateArgLists.addOuterTemplateArguments(None);
+
   Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
   EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated);
-  return SemaRef.SubstExpr(Param->getDefaultArgument(), AllTemplateArgs);
+  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
 }
 
 /// \brief Substitute template arguments into the default template argument for
@@ -3076,32 +3082,35 @@ SubstDefaultTemplateArgument(Sema &SemaRef,
                              TemplateTemplateParmDecl *Param,
                        SmallVectorImpl<TemplateArgument> &Converted,
                              NestedNameSpecifierLoc &QualifierLoc) {
-  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
-                                    Converted.data(), Converted.size());
-
-  MultiLevelTemplateArgumentList AllTemplateArgs
-    = SemaRef.getTemplateInstantiationArgs(Template, &TemplateArgs);
-
-  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
-                                   Template, Converted,
+  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc, Template, Converted,
                                    SourceRange(TemplateLoc, RAngleLoc));
   if (Inst)
     return TemplateName();
 
+  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
+                                    Converted.data(), Converted.size());
+
+  // Only substitute for the innermost template argument list.
+  MultiLevelTemplateArgumentList TemplateArgLists;
+  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
+  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
+    TemplateArgLists.addOuterTemplateArguments(None);
+
   Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
-  // Substitute into the nested-name-specifier first, 
+  // Substitute into the nested-name-specifier first,
   QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
   if (QualifierLoc) {
-    QualifierLoc = SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, 
-                                                       AllTemplateArgs);
+    QualifierLoc =
+        SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
     if (!QualifierLoc)
       return TemplateName();
   }
-  
-  return SemaRef.SubstTemplateName(QualifierLoc,
-                      Param->getDefaultArgument().getArgument().getAsTemplate(),
-                              Param->getDefaultArgument().getTemplateNameLoc(),
-                                   AllTemplateArgs);
+
+  return SemaRef.SubstTemplateName(
+             QualifierLoc,
+             Param->getDefaultArgument().getArgument().getAsTemplate(),
+             Param->getDefaultArgument().getTemplateNameLoc(),
+             TemplateArgLists);
 }
 
 /// \brief If the given template parameter has a default template
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index a797ae66b19..5d6847fdf0e 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1737,8 +1737,13 @@ Decl *TemplateDeclInstantiator::VisitTemplateTypeParmDecl(
                                  D->isParameterPack());
   Inst->setAccess(AS_public);
 
-  if (D->hasDefaultArgument())
-    Inst->setDefaultArgument(D->getDefaultArgumentInfo(), false);
+  if (D->hasDefaultArgument()) {
+    TypeSourceInfo *InstantiatedDefaultArg =
+        SemaRef.SubstType(D->getDefaultArgumentInfo(), TemplateArgs,
+                          D->getDefaultArgumentLoc(), D->getDeclName());
+    if (InstantiatedDefaultArg)
+      Inst->setDefaultArgument(InstantiatedDefaultArg, false);
+  }
 
   // Introduce this template parameter's instantiation into the instantiation
   // scope.
@@ -1888,7 +1893,11 @@ Decl *TemplateDeclInstantiator::VisitNonTypeTemplateParmDecl(
   if (Invalid)
     Param->setInvalidDecl();
 
-  Param->setDefaultArgument(D->getDefaultArgument(), false);
+  if (D->hasDefaultArgument()) {
+    ExprResult Value = SemaRef.SubstExpr(D->getDefaultArgument(), TemplateArgs);
+    if (!Value.isInvalid())
+      Param->setDefaultArgument(Value.get(), false);
+  }
 
   // Introduce this template parameter's instantiation into the instantiation
   // scope.
@@ -2011,7 +2020,21 @@ TemplateDeclInstantiator::VisitTemplateTemplateParmDecl(
                                              D->getPosition(),
                                              D->isParameterPack(),
                                              D->getIdentifier(), InstParams);
-  Param->setDefaultArgument(D->getDefaultArgument(), false);
+  if (D->hasDefaultArgument()) {
+    NestedNameSpecifierLoc QualifierLoc =
+        D->getDefaultArgument().getTemplateQualifierLoc();
+    QualifierLoc =
+        SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgs);
+    TemplateName TName = SemaRef.SubstTemplateName(
+        QualifierLoc, D->getDefaultArgument().getArgument().getAsTemplate(),
+        D->getDefaultArgument().getTemplateNameLoc(), TemplateArgs);
+    if (!TName.isNull())
+      Param->setDefaultArgument(
+          TemplateArgumentLoc(TemplateArgument(TName),
+                              D->getDefaultArgument().getTemplateQualifierLoc(),
+                              D->getDefaultArgument().getTemplateNameLoc()),
+          false);
+  }
   Param->setAccess(AS_public);
 
   // Introduce this template parameter's instantiation into the instantiation
diff --git a/clang/test/CodeGenCXX/mangle.cpp b/clang/test/CodeGenCXX/mangle.cpp
index a9daa0df619..f03f499fe13 100644
--- a/clang/test/CodeGenCXX/mangle.cpp
+++ b/clang/test/CodeGenCXX/mangle.cpp
@@ -910,3 +910,26 @@ namespace test40 {
   };
   void g() { f(); }
 }
+
+namespace test41 {
+  // CHECK: define linkonce_odr void @_ZN6test414funcINS_1XEEEvNS_3fooILi20ES1_EE
+  template <int i, class T> struct foo {
+    template <class T2 = T> friend void func(foo x) {}
+  };
+
+  struct X {};
+
+  void g() { func(foo<20, X>()); }
+}
+
+namespace test42 {
+  // CHECK: define linkonce_odr void @_ZN6test424funcINS_1XEEEvNS_3fooILi20ES1_EE
+  template <int i, template <class> class T> struct foo {
+    template <template <class> class T2 = T> friend void func(foo x) {}
+  };
+
+  template <class V> struct X {
+  };
+
+  void g() { func(foo<20, X>()); }
+}
diff --git a/clang/test/SemaCXX/cxx1y-deduced-return-type.cpp b/clang/test/SemaCXX/cxx1y-deduced-return-type.cpp
index 26d776f375d..9e779bf170a 100644
--- a/clang/test/SemaCXX/cxx1y-deduced-return-type.cpp
+++ b/clang/test/SemaCXX/cxx1y-deduced-return-type.cpp
@@ -399,3 +399,12 @@ namespace CurrentInstantiation {
   template<typename T> auto U<T>::f() { return T(); }
   template int U<short>::g(); // ok
 }
+
+namespace WithDefaultArgs {
+  template<typename U> struct A {
+    template<typename T = U> friend auto f(A) { return []{}; }
+  };
+  template<typename T> void f();
+  using T = decltype(f(A<int>()));
+  using T = decltype(f<int>(A<int>()));
+}
diff --git a/clang/test/SemaTemplate/default-arguments-cxx0x.cpp b/clang/test/SemaTemplate/default-arguments-cxx0x.cpp
index 4c815f65587..4cfd7a5843f 100644
--- a/clang/test/SemaTemplate/default-arguments-cxx0x.cpp
+++ b/clang/test/SemaTemplate/default-arguments-cxx0x.cpp
@@ -25,3 +25,34 @@ void g1() {
   float &fr = f1(15);
   int &ir = f1(HasValue());
 }
+
+namespace PR16689 {
+  template <typename T1, typename T2> class tuple {
+  public:
+      template <typename = T2>
+      constexpr tuple() {}
+  };
+  template <class X, class... Y> struct a : public X {
+    using X::X;
+  };
+  auto x = a<tuple<int, int> >();
+}
+
+namespace PR16975 {
+  template <typename...> struct is {
+    constexpr operator bool() const { return false; }
+  };
+
+  template <typename... Types>
+  struct bar {
+    template <typename T,
+              bool = is<Types...>()>
+    bar(T);
+  };
+
+  struct baz : public bar<> {
+    using bar::bar;
+  };
+
+  baz data{0};
+}
diff --git a/clang/test/SemaTemplate/default-arguments.cpp b/clang/test/SemaTemplate/default-arguments.cpp
index aca5c972adb..439a3039211 100644
--- a/clang/test/SemaTemplate/default-arguments.cpp
+++ b/clang/test/SemaTemplate/default-arguments.cpp
@@ -47,11 +47,13 @@ template<typename T> struct X1 { };
 
 template<typename T>
 struct X2 {
-  template<typename U = typename X1<T>::type> // expected-error{{no type named}}
-  struct Inner1 { };
+  template<typename U = typename X1<T>::type> // expected-error{{no type named 'type' in 'X1<int>'}} \
+                                              // expected-error{{no type named 'type' in 'X1<char>'}}
+  struct Inner1 { }; // expected-note{{template is declared here}}
   
-  template<T Value = X1<T>::value> // expected-error{{no member named 'value'}}
-  struct NonType1 { };
+  template<T Value = X1<T>::value> // expected-error{{no member named 'value' in 'X1<int>'}} \
+                                   // expected-error{{no member named 'value' in 'X1<char>'}}
+  struct NonType1 { }; // expected-note{{template is declared here}}
   
   template<T Value>
   struct Inner2 { };
@@ -67,17 +69,17 @@ struct X2 {
   };
 };
 
-X2<int> x2i;
+X2<int> x2i; // expected-note{{in instantiation of template class 'X2<int>' requested here}}
 X2<int>::Inner1<float> x2iif;
 
-X2<int>::Inner1<> x2bad; // expected-note{{instantiation of default argument}}
+X2<int>::Inner1<> x2bad; // expected-error{{too few template arguments for class template 'Inner1'}}
 
 X2<int>::NonType1<'a'> x2_nontype1;
-X2<int>::NonType1<> x2_nontype1_bad; // expected-note{{instantiation of default argument}}
+X2<int>::NonType1<> x2_nontype1_bad; // expected-error{{too few template arguments for class template 'NonType1'}}
 
 // Check multi-level substitution into template type arguments
 X2<int>::Inner3<float>::VeryInner<> vi;
-X2<char>::Inner3<int>::NonType2<> x2_deep_nontype;
+X2<char>::Inner3<int>::NonType2<> x2_deep_nontype; // expected-note{{in instantiation of template class 'X2<char>' requested here}}
 
 template<typename T, typename U>
 struct is_same { static const bool value = false; };
@@ -147,3 +149,13 @@ namespace PR16288 {
   template<typename T, typename U>
   void S<X>::f() {}
 }
+
+namespace DR1635 {
+  template <class T> struct X {
+    template <class U = typename T::type> static void f(int) {} // expected-error {{type 'int' cannot be used prior to '::' because it has no members}} \
+                                                                // expected-warning {{C++11}}
+    static void f(...) {}
+  };
+
+  int g() { X<int>::f(0); } // expected-note {{in instantiation of template class 'DR1635::X<int>' requested here}}
+}