When substituting the template argument for a pointer non-type

template parameter, perform array/function decay (if needed), take the
address of the argument (if needed), perform qualification conversions
(if needed), and remove any top-level cv-qualifiers from the resulting
expression. Fixes PR6226.

llvm-svn: 95309

clang/lib/Sema/SemaTemplateInstantiate.cpp

@@ -718,7 +718,8 @@ TemplateInstantiator::TransformDeclRefExpr(DeclRefExpr *E) {
         if (!VD)
           return SemaRef.ExprError();
 
-        if (VD->getDeclContext()->isRecord()) {
+        if (VD->getDeclContext()->isRecord() && 
+            (isa<CXXMethodDecl>(VD) || isa<FieldDecl>(VD))) {
           // If the value is a class member, we might have a pointer-to-member.
           // Determine whether the non-type template template parameter is of
           // pointer-to-member type. If so, we need to build an appropriate
@@ -746,21 +747,51 @@ TemplateInstantiator::TransformDeclRefExpr(DeclRefExpr *E) {
                                                 move(RefExpr));
           }
         }
-        if (NTTP->getType()->isPointerType() &&
-            !VD->getType()->isPointerType()) {
-          // If the template argument is expected to be a pointer and value
-          // isn't inherently of pointer type, then it is specified with '&...'
-          // to indicate its address should be used. Build an expression to
-          // take the address of the argument.
+        if (NTTP->getType()->isPointerType()) {
+          // If the template argument is expected to be a pointer
+          // type, we may have to decay array/pointer references, take
+          // the address of the argument, or perform cv-qualification
+          // adjustments to get the type of the rvalue right. Do so.
           OwningExprResult RefExpr
             = SemaRef.BuildDeclRefExpr(VD, VD->getType().getNonReferenceType(),
                                        E->getLocation());
           if (RefExpr.isInvalid())
             return SemaRef.ExprError();
 
-          return SemaRef.CreateBuiltinUnaryOp(E->getLocation(),
-                                              UnaryOperator::AddrOf,
-                                              move(RefExpr));
+          // Decay functions and arrays.
+          Expr *RefE = (Expr *)RefExpr.get();
+          SemaRef.DefaultFunctionArrayConversion(RefE);
+          if (RefE != RefExpr.get()) {
+            RefExpr.release();
+            RefExpr = SemaRef.Owned(RefE);
+          }
+
+          // If the unqualified types are different and a a
+          // qualification conversion won't fix them types, we need to
+          // take the address.  FIXME: Should we encode these steps in
+          // the template argument, then replay them here, like a
+          // miniature InitializationSequence?
+          if (!SemaRef.Context.hasSameUnqualifiedType(RefE->getType(), 
+                                                      NTTP->getType()) &&
+              !SemaRef.IsQualificationConversion(RefE->getType(),
+                                                 NTTP->getType())) {
+            RefExpr = SemaRef.CreateBuiltinUnaryOp(E->getLocation(),
+                                                   UnaryOperator::AddrOf,
+                                                   move(RefExpr));
+            if (RefExpr.isInvalid())
+              return SemaRef.ExprError();
+
+            RefE = (Expr *)RefExpr.get();
+            assert(SemaRef.IsQualificationConversion(RefE->getType(),
+                                                     NTTP->getType()));
+          }
+
+          // Strip top-level cv-qualifiers off the type.
+          RefExpr.release();
+          SemaRef.ImpCastExprToType(RefE, 
+                                    NTTP->getType().getUnqualifiedType(),
+                                    CastExpr::CK_NoOp);
+          return SemaRef.Owned(RefE);
         }
 
         return SemaRef.BuildDeclRefExpr(VD, VD->getType().getNonReferenceType(),

clang/test/CXX/temp/temp.arg/temp.arg.nontype/p5.cpp

@@ -11,6 +11,43 @@
 //        qualification conversions (4.4) and the array-to-pointer conversion
 //        (4.2) are applied; if the template-argument is of type
 //        std::nullptr_t, the null pointer conversion (4.10) is applied.
+namespace pointer_to_object_parameters {
+  // PR6226
+  struct Str {
+    Str(const char *);
+  };
+
+  template<const char *s>
+  struct A {
+    Str get() { return s; }
+  };
+
+  char hello[6] = "Hello";
+  extern const char world[6];
+  const char world[6] = "world";
+  void test() {
+    (void)A<hello>().get();
+    (void)A<world>().get();
+  }
+
+  class X {
+  public:
+    X();
+    X(int, int);
+    operator int() const;
+  };
+  
+  template<X const *Ptr> struct A2;
+  
+  X *X_ptr;
+  X an_X;
+  X array_of_Xs[10];
+  A2<X_ptr> *a12;
+  A2<array_of_Xs> *a13;
+  A2<&an_X> *a13_2;
+  A2<(&an_X)> *a13_3; // expected-error{{non-type template argument cannot be surrounded by parentheses}}
+}
+
 //     -- For a non-type template-parameter of type reference to object, no
 //        conversions apply. The type referred to by the reference may be more
 //        cv-qualified than the (otherwise identical) type of the

clang/test/SemaTemplate/temp_arg_nontype.cpp

@@ -34,16 +34,6 @@ public:
 };
 A<X(17, 42)> *a11; // expected-error{{non-type template argument of type 'class X' must have an integral or enumeration type}}
 
-template<X const *Ptr> struct A2;
-
-X *X_ptr;
-X an_X;
-X array_of_Xs[10];
-A2<X_ptr> *a12;
-A2<array_of_Xs> *a13;
-A2<&an_X> *a13_2;
-A2<(&an_X)> *a13_3; // expected-error{{non-type template argument cannot be surrounded by parentheses}}
-
 float f(float);
 
 float g(float);
@@ -67,6 +57,7 @@ struct Y { } y;
 
 volatile X * X_volatile_ptr;
 template<X const &AnX> struct A4; // expected-note 2{{template parameter is declared here}}
+X an_X;
 A4<an_X> *a15_1; // okay
 A4<*X_volatile_ptr> *a15_2; // expected-error{{reference binding of non-type template parameter of type 'class X const &' to template argument of type 'class X volatile' ignores qualifiers}}
 A4<y> *15_3; //  expected-error{{non-type template parameter of reference type 'class X const &' cannot bind to template argument of type 'struct Y'}} \