Implement "incremental" template instantiation for non-type template

parameters and template type parameters, which occurs when
substituting into the declarations of member templates inside class
templates. This eliminates errors about our inability to "reduce
non-type template parameter depth", fixing PR5311.

Also fixes a bug when instantiating a template type parameter
declaration in a member template, where we weren't properly reducing
the template parameter's depth.

LLVM's StringSwitch header now parses.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@85669 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 122 insertions, 58 deletions

diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index 5197516e46..3281fc450c 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -3117,7 +3117,7 @@ public:
     llvm::DenseMap<const Decl *, Decl *> LocalDecls;
 
     /// \brief The outer scope, in which contains local variable
-    /// definitions from some other instantiation (that is not
+    /// definitions from some other instantiation (that may not be
     /// relevant to this particular scope).
     LocalInstantiationScope *Outer;
 
@@ -3126,9 +3126,13 @@ public:
     LocalInstantiationScope &operator=(const LocalInstantiationScope &);
 
   public:
-    LocalInstantiationScope(Sema &SemaRef)
+    LocalInstantiationScope(Sema &SemaRef, bool CombineWithOuterScope = false)
       : SemaRef(SemaRef), Outer(SemaRef.CurrentInstantiationScope) {
-      SemaRef.CurrentInstantiationScope = this;
+      if (!CombineWithOuterScope)
+        SemaRef.CurrentInstantiationScope = this;
+      else
+        assert(SemaRef.CurrentInstantiationScope && 
+               "No outer instantiation scope?");
     }
 
     ~LocalInstantiationScope() {
@@ -3149,6 +3153,11 @@ public:
       return cast<ParmVarDecl>(getInstantiationOf(cast<Decl>(Var)));
     }
 
+    NonTypeTemplateParmDecl *getInstantiationOf(
+                                          const NonTypeTemplateParmDecl *Var) {
+      return cast<NonTypeTemplateParmDecl>(getInstantiationOf(cast<Decl>(Var)));
+    }
+    
     void InstantiatedLocal(const Decl *D, Decl *Inst) {
       Decl *&Stored = LocalDecls[D];
       assert(!Stored && "Already instantiated this local");
diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 8fab8f62e4..e79511f923 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -562,58 +562,59 @@ TemplateInstantiator::TransformDeclRefExpr(DeclRefExpr *E) {
   // FIXME: Clean this up a bit
   NamedDecl *D = E->getDecl();
   if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D)) {
-    if (NTTP->getDepth() >= TemplateArgs.getNumLevels()) {
-      assert(false && "Cannot reduce non-type template parameter depth yet");
-      return getSema().ExprError();
-    }
-
-    // If the corresponding template argument is NULL or non-existent, it's
-    // because we are performing instantiation from explicitly-specified
-    // template arguments in a function template, but there were some
-    // arguments left unspecified.
-    if (!TemplateArgs.hasTemplateArgument(NTTP->getDepth(),
-                                          NTTP->getPosition()))
-      return SemaRef.Owned(E->Retain());
-
-    const TemplateArgument &Arg = TemplateArgs(NTTP->getDepth(),
-                                               NTTP->getPosition());
-
-    // The template argument itself might be an expression, in which
-    // case we just return that expression.
-    if (Arg.getKind() == TemplateArgument::Expression)
-      return SemaRef.Owned(Arg.getAsExpr()->Retain());
-
-    if (Arg.getKind() == TemplateArgument::Declaration) {
-      ValueDecl *VD = cast<ValueDecl>(Arg.getAsDecl());
-
-      VD = cast_or_null<ValueDecl>(
-                              getSema().FindInstantiatedDecl(VD, TemplateArgs));
-      if (!VD)
-        return SemaRef.ExprError();
-
-      return SemaRef.BuildDeclRefExpr(VD, VD->getType(), E->getLocation(),
-                                      /*FIXME:*/false, /*FIXME:*/false);
-    }
+    if (NTTP->getDepth() < TemplateArgs.getNumLevels()) {
+      
+      // If the corresponding template argument is NULL or non-existent, it's
+      // because we are performing instantiation from explicitly-specified
+      // template arguments in a function template, but there were some
+      // arguments left unspecified.
+      if (!TemplateArgs.hasTemplateArgument(NTTP->getDepth(),
+                                            NTTP->getPosition()))
+        return SemaRef.Owned(E->Retain());
+
+      const TemplateArgument &Arg = TemplateArgs(NTTP->getDepth(),
+                                                 NTTP->getPosition());
+
+      // The template argument itself might be an expression, in which
+      // case we just return that expression.
+      if (Arg.getKind() == TemplateArgument::Expression)
+        return SemaRef.Owned(Arg.getAsExpr()->Retain());
+
+      if (Arg.getKind() == TemplateArgument::Declaration) {
+        ValueDecl *VD = cast<ValueDecl>(Arg.getAsDecl());
+
+        VD = cast_or_null<ValueDecl>(
+                                getSema().FindInstantiatedDecl(VD, TemplateArgs));
+        if (!VD)
+          return SemaRef.ExprError();
+
+        return SemaRef.BuildDeclRefExpr(VD, VD->getType(), E->getLocation(),
+                                        /*FIXME:*/false, /*FIXME:*/false);
+      }
 
-    assert(Arg.getKind() == TemplateArgument::Integral);
-    QualType T = Arg.getIntegralType();
-    if (T->isCharType() || T->isWideCharType())
-      return SemaRef.Owned(new (SemaRef.Context) CharacterLiteral(
-                                            Arg.getAsIntegral()->getZExtValue(),
-                                            T->isWideCharType(),
-                                            T,
-                                            E->getSourceRange().getBegin()));
-    if (T->isBooleanType())
-      return SemaRef.Owned(new (SemaRef.Context) CXXBoolLiteralExpr(
-                                          Arg.getAsIntegral()->getBoolValue(),
-                                          T,
-                                          E->getSourceRange().getBegin()));
-
-    assert(Arg.getAsIntegral()->getBitWidth() == SemaRef.Context.getIntWidth(T));
-    return SemaRef.Owned(new (SemaRef.Context) IntegerLiteral(
-                                              *Arg.getAsIntegral(),
+      assert(Arg.getKind() == TemplateArgument::Integral);
+      QualType T = Arg.getIntegralType();
+      if (T->isCharType() || T->isWideCharType())
+        return SemaRef.Owned(new (SemaRef.Context) CharacterLiteral(
+                                              Arg.getAsIntegral()->getZExtValue(),
+                                              T->isWideCharType(),
                                               T,
                                               E->getSourceRange().getBegin()));
+      if (T->isBooleanType())
+        return SemaRef.Owned(new (SemaRef.Context) CXXBoolLiteralExpr(
+                                            Arg.getAsIntegral()->getBoolValue(),
+                                            T,
+                                            E->getSourceRange().getBegin()));
+
+      assert(Arg.getAsIntegral()->getBitWidth() == SemaRef.Context.getIntWidth(T));
+      return SemaRef.Owned(new (SemaRef.Context) IntegerLiteral(
+                                                *Arg.getAsIntegral(),
+                                                T,
+                                                E->getSourceRange().getBegin()));
+    }
+    
+    // We have a non-type template parameter that isn't fully substituted;
+    // FindInstantiatedDecl will find it in the local instantiation scope.
   }
 
   NamedDecl *InstD = SemaRef.FindInstantiatedDecl(D, TemplateArgs);
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index f8f2217464..27275230f7 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -409,6 +409,9 @@ namespace {
 }
 
 Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
+  // Create a local instantiation scope for this class template, which
+  // will contain the instantiations of the template parameters.
+  Sema::LocalInstantiationScope Scope(SemaRef);
   TemplateParameterList *TempParams = D->getTemplateParameters();
   TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
   if (!InstParams)
@@ -491,8 +494,12 @@ TemplateDeclInstantiator::VisitClassTemplatePartialSpecializationDecl(
 
 Decl *
 TemplateDeclInstantiator::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
-  // FIXME: Dig out the out-of-line definition of this function template?
-
+  // Create a local instantiation scope for this function template, which
+  // will contain the instantiations of the template parameters and then get
+  // merged with the local instantiation scope for the function template 
+  // itself.
+  Sema::LocalInstantiationScope Scope(SemaRef);
+  
   TemplateParameterList *TempParams = D->getTemplateParameters();
   TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
   if (!InstParams)
@@ -582,7 +589,7 @@ Decl *TemplateDeclInstantiator::VisitCXXRecordDecl(CXXRecordDecl *D) {
       return Info->Function;
   }
 
-  Sema::LocalInstantiationScope Scope(SemaRef);
+  Sema::LocalInstantiationScope Scope(SemaRef, TemplateParams != 0);
 
   llvm::SmallVector<ParmVarDecl *, 4> Params;
   QualType T = SubstFunctionType(D, Params);
@@ -711,7 +718,7 @@ TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D,
       return Info->Function;
   }
 
-  Sema::LocalInstantiationScope Scope(SemaRef);
+  Sema::LocalInstantiationScope Scope(SemaRef, TemplateParams != 0);
 
   llvm::SmallVector<ParmVarDecl *, 4> Params;
   QualType T = SubstFunctionType(D, Params);
@@ -886,7 +893,7 @@ Decl *TemplateDeclInstantiator::VisitTemplateTypeParmDecl(
 
   TemplateTypeParmDecl *Inst =
     TemplateTypeParmDecl::Create(SemaRef.Context, Owner, D->getLocation(),
-                                 TTPT->getDepth(), TTPT->getIndex(),
+                                 TTPT->getDepth() - 1, TTPT->getIndex(),
                                  TTPT->getName(),
                                  D->wasDeclaredWithTypename(),
                                  D->isParameterPack());
@@ -904,6 +911,10 @@ Decl *TemplateDeclInstantiator::VisitTemplateTypeParmDecl(
                              D->defaultArgumentWasInherited() /* preserve? */);
   }
 
+  // Introduce this template parameter's instantiation into the instantiation 
+  // scope.
+  SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Inst);
+  
   return Inst;
 }
 
@@ -940,6 +951,10 @@ Decl *TemplateDeclInstantiator::VisitNonTypeTemplateParmDecl(
     Param->setInvalidDecl();
   
   Param->setDefaultArgument(D->getDefaultArgument());
+  
+  // Introduce this template parameter's instantiation into the instantiation 
+  // scope.
+  SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Param);
   return Param;
 }
 
@@ -1024,6 +1039,11 @@ bool
 TemplateDeclInstantiator::InstantiateClassTemplatePartialSpecialization(
                                             ClassTemplateDecl *ClassTemplate,
                           ClassTemplatePartialSpecializationDecl *PartialSpec) {
+  // Create a local instantiation scope for this class template partial
+  // specialization, which will contain the instantiations of the template
+  // parameters.
+  Sema::LocalInstantiationScope Scope(SemaRef);
+  
   // Substitute into the template parameters of the class template partial
   // specialization.
   TemplateParameterList *TempParams = PartialSpec->getTemplateParameters();
@@ -1773,7 +1793,9 @@ NamedDecl *Sema::FindInstantiatedDecl(NamedDecl *D,
   }
 
   DeclContext *ParentDC = D->getDeclContext();
-  if (isa<ParmVarDecl>(D) || ParentDC->isFunctionOrMethod()) {
+  if (isa<ParmVarDecl>(D) || isa<NonTypeTemplateParmDecl>(D) ||
+      isa<TemplateTypeParmDecl>(D) || isa<TemplateTypeParmDecl>(D) ||
+      ParentDC->isFunctionOrMethod()) {
     // D is a local of some kind. Look into the map of local
     // declarations to their instantiations.
     return cast<NamedDecl>(CurrentInstantiationScope->getInstantiationOf(D));
diff --git a/test/SemaTemplate/instantiate-non-type-template-parameter.cpp b/test/SemaTemplate/instantiate-non-type-template-parameter.cpp
new file mode 100644
index 0000000000..32acbd0d8b
--- /dev/null
+++ b/test/SemaTemplate/instantiate-non-type-template-parameter.cpp
@@ -0,0 +1,14 @@
+// RUN: clang-cc -fsyntax-only -verify %s
+
+// PR5311
+template<typename T>
+class StringSwitch {
+public:
+  template<unsigned N>
+  void Case(const char (&S)[N], const int & Value) {
+  }
+};
+
+int main(int argc, char *argv[]) {
+  (void)StringSwitch<int>();
+}
diff --git a/test/SemaTemplate/member-template-access-expr.cpp b/test/SemaTemplate/member-template-access-expr.cpp
index feef7926fb..0238cd53c5 100644
--- a/test/SemaTemplate/member-template-access-expr.cpp
+++ b/test/SemaTemplate/member-template-access-expr.cpp
@@ -75,3 +75,21 @@ void test_X1(X1 x1) {
   float* (*fp7)(int) = X1::f2<>;
   float* (*fp8)(float) = X1::f2<float>;  
 }
+
+template<int A> struct X2 { 
+  int m;
+};
+
+template<typename T>
+struct X3 : T { };
+
+template<typename T>
+struct X4 {
+  template<typename U>
+  void f(X2<sizeof(X3<U>().U::m)>);
+};
+
+void f(X4<X3<int> > x4i) {
+  X2<sizeof(int)> x2;
+  x4i.f<X2<sizeof(int)> >(x2);
+}