From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Sun, 21 Oct 2012 03:28:35 +0000 (+0000)
Subject: Unrevert r166268, reverted in r166272, with a fix for the issue which Nick
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=efeeccfb5efa94b6b4198298a80ad9a699bebcce;p=clang

Unrevert r166268, reverted in r166272, with a fix for the issue which Nick
found: if an overloaded operator& is present before a template definition,
the expression &T::foo is represented as a CXXOperatorCallExpr, not as a
UnaryOperator, so we didn't notice that it's permitted to reference a non-static
data member of an unrelated class.

While investigating this, I discovered another problem in this area: we are
treating template default arguments as unevaluated contexts during substitution,
resulting in performing incorrect checks for uses of non-static data members in
C++11. That is not fixed by this patch (I'll look into this soon; it's related
to the failure to correctly instantiate constexpr function templates), but was
resulting in this bug not firing in C++11 mode (except with -Wc++98-compat).

Original message:

PR14124: When performing template instantiation of a qualified-id outside of a
class, diagnose if the qualified-id instantiates to a non-static class member.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@166385 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 658a60c62f..df9433e0db 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -2911,7 +2911,8 @@ public:
                                   bool HasTrailingLParen);
 
   ExprResult BuildQualifiedDeclarationNameExpr(CXXScopeSpec &SS,
-                                         const DeclarationNameInfo &NameInfo);
+                                         const DeclarationNameInfo &NameInfo,
+                                               bool IsAddressOfOperand);
   ExprResult BuildDependentDeclRefExpr(const CXXScopeSpec &SS,
                                        SourceLocation TemplateKWLoc,
                                 const DeclarationNameInfo &NameInfo,
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 6a6fe897c5..838d33150f 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1895,7 +1895,8 @@ ExprResult Sema::ActOnIdExpression(Scope *S,
 /// this path.
 ExprResult
 Sema::BuildQualifiedDeclarationNameExpr(CXXScopeSpec &SS,
-                                        const DeclarationNameInfo &NameInfo) {
+                                        const DeclarationNameInfo &NameInfo,
+                                        bool IsAddressOfOperand) {
   DeclContext *DC;
   if (!(DC = computeDeclContext(SS, false)) || DC->isDependentContext())
     return BuildDependentDeclRefExpr(SS, /*TemplateKWLoc=*/SourceLocation(),
@@ -1916,7 +1917,16 @@ Sema::BuildQualifiedDeclarationNameExpr(CXXScopeSpec &SS,
     return ExprError();
   }
 
-  return BuildDeclarationNameExpr(SS, R, /*ADL*/ false);
+  // Defend against this resolving to an implicit member access. We usually
+  // won't get here if this might be a legitimate a class member (we end up in
+  // BuildMemberReferenceExpr instead), but this can be valid if we're forming
+  // a pointer-to-member or in an unevaluated context in C++11.
+  if (!R.empty() && (*R.begin())->isCXXClassMember() && !IsAddressOfOperand)
+    return BuildPossibleImplicitMemberExpr(SS,
+                                           /*TemplateKWLoc=*/SourceLocation(),
+                                           R, /*TemplateArgs=*/0);
+
+  return BuildDeclarationNameExpr(SS, R, /* ADL */ false);
 }
 
 /// LookupInObjCMethod - The parser has read a name in, and Sema has
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index 9655e85303..5b5122f5b0 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -574,6 +574,10 @@ public:
   /// \brief Transform the captures and body of a lambda expression.
   ExprResult TransformLambdaScope(LambdaExpr *E, CXXMethodDecl *CallOperator);
 
+  ExprResult TransformAddressOfOperand(Expr *E);
+  ExprResult TransformDependentScopeDeclRefExpr(DependentScopeDeclRefExpr *E,
+                                                bool IsAddressOfOperand);
+
 #define STMT(Node, Parent)                        \
   StmtResult Transform##Node(Node *S);
 #define EXPR(Node, Parent)                        \
@@ -2073,7 +2077,8 @@ public:
                                           NestedNameSpecifierLoc QualifierLoc,
                                           SourceLocation TemplateKWLoc,
                                        const DeclarationNameInfo &NameInfo,
-                              const TemplateArgumentListInfo *TemplateArgs) {
+                              const TemplateArgumentListInfo *TemplateArgs,
+                                          bool IsAddressOfOperand) {
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
 
@@ -2081,7 +2086,8 @@ public:
       return getSema().BuildQualifiedTemplateIdExpr(SS, TemplateKWLoc,
                                                     NameInfo, TemplateArgs);
 
-    return getSema().BuildQualifiedDeclarationNameExpr(SS, NameInfo);
+    return getSema().BuildQualifiedDeclarationNameExpr(SS, NameInfo,
+                                                       IsAddressOfOperand);
   }
 
   /// \brief Build a new template-id expression.
@@ -6138,10 +6144,22 @@ TreeTransform<Derived>::TransformParenExpr(ParenExpr *E) {
                                        E->getRParen());
 }
 
+/// \brief The operand of a unary address-of operator has special rules: it's
+/// allowed to refer to a non-static member of a class even if there's no 'this'
+/// object available.
+template<typename Derived>
+ExprResult
+TreeTransform<Derived>::TransformAddressOfOperand(Expr *E) {
+  if (DependentScopeDeclRefExpr *DRE = dyn_cast<DependentScopeDeclRefExpr>(E))
+    return getDerived().TransformDependentScopeDeclRefExpr(DRE, true);
+  else
+    return getDerived().TransformExpr(E);
+}
+
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformUnaryOperator(UnaryOperator *E) {
-  ExprResult SubExpr = getDerived().TransformExpr(E->getSubExpr());
+  ExprResult SubExpr = TransformAddressOfOperand(E->getSubExpr());
   if (SubExpr.isInvalid())
     return ExprError();
 
@@ -6842,7 +6860,11 @@ TreeTransform<Derived>::TransformCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
   if (Callee.isInvalid())
     return ExprError();
 
-  ExprResult First = getDerived().TransformExpr(E->getArg(0));
+  ExprResult First;
+  if (E->getOperator() == OO_Amp)
+    First = getDerived().TransformAddressOfOperand(E->getArg(0));
+  else
+    First = getDerived().TransformExpr(E->getArg(0));
   if (First.isInvalid())
     return ExprError();
 
@@ -7671,6 +7693,14 @@ template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformDependentScopeDeclRefExpr(
                                                DependentScopeDeclRefExpr *E) {
+  return TransformDependentScopeDeclRefExpr(E, /*IsAddressOfOperand*/false);
+}
+
+template<typename Derived>
+ExprResult
+TreeTransform<Derived>::TransformDependentScopeDeclRefExpr(
+                                               DependentScopeDeclRefExpr *E,
+                                               bool IsAddressOfOperand) {
   NestedNameSpecifierLoc QualifierLoc
   = getDerived().TransformNestedNameSpecifierLoc(E->getQualifierLoc());
   if (!QualifierLoc)
@@ -7697,7 +7727,8 @@ TreeTransform<Derived>::TransformDependentScopeDeclRefExpr(
     return getDerived().RebuildDependentScopeDeclRefExpr(QualifierLoc,
                                                          TemplateKWLoc,
                                                          NameInfo,
-                                                         /*TemplateArgs*/ 0);
+                                                         /*TemplateArgs*/ 0,
+                                                         IsAddressOfOperand);
   }
 
   TemplateArgumentListInfo TransArgs(E->getLAngleLoc(), E->getRAngleLoc());
@@ -7709,7 +7740,8 @@ TreeTransform<Derived>::TransformDependentScopeDeclRefExpr(
   return getDerived().RebuildDependentScopeDeclRefExpr(QualifierLoc,
                                                        TemplateKWLoc,
                                                        NameInfo,
-                                                       &TransArgs);
+                                                       &TransArgs,
+                                                       IsAddressOfOperand);
 }
 
 template<typename Derived>
diff --git a/test/SemaCXX/decltype-overloaded-functions.cpp b/test/SemaCXX/decltype-overloaded-functions.cpp
index 2ed4465b5b..c1d01fc9af 100644
--- a/test/SemaCXX/decltype-overloaded-functions.cpp
+++ b/test/SemaCXX/decltype-overloaded-functions.cpp
@@ -1,16 +1,16 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11
 
-void f(); // expected-note{{possible target for call}}
-void f(int); // expected-note{{possible target for call}}
+void f();  // expected-note{{possible target for call}}
+void f(int);  // expected-note{{possible target for call}}
 decltype(f) a;  // expected-error{{reference to overloaded function could not be resolved; did you mean to call it with no arguments?}} expected-error {{variable has incomplete type 'decltype(f())' (aka 'void')}}
 
 template<typename T> struct S {
-  decltype(T::f) * f; // expected-error{{reference to overloaded function could not be resolved; did you mean to call it with no arguments?}} expected-error {{call to non-static member function without an object argument}}
+  decltype(T::f) * f; // expected-error {{call to non-static member function without an object argument}}
 };
 
 struct K { 
-  void f();  // expected-note{{possible target for call}}
-  void f(int); // expected-note{{possible target for call}}
+  void f();
+  void f(int);
 };
 S<K> b; // expected-note{{in instantiation of template class 'S<K>' requested here}}
 
diff --git a/test/SemaCXX/warn-assignment-condition.cpp b/test/SemaCXX/warn-assignment-condition.cpp
index 04f2e79525..09084e36bb 100644
--- a/test/SemaCXX/warn-assignment-condition.cpp
+++ b/test/SemaCXX/warn-assignment-condition.cpp
@@ -133,14 +133,14 @@ void test2() {
 
 namespace rdar9027658 {
 template <typename T>
-void f() {
-    if ((T::g == 3)) { } // expected-warning {{equality comparison with extraneous parentheses}} \
+void f(T t) {
+    if ((t.g == 3)) { } // expected-warning {{equality comparison with extraneous parentheses}} \
                          // expected-note {{use '=' to turn this equality comparison into an assignment}} \
                          // expected-note {{remove extraneous parentheses around the comparison to silence this warning}}
 }
 
 struct S { int g; };
 void test() {
-  f<S>(); // expected-note {{in instantiation}}
+  f(S()); // expected-note {{in instantiation}}
 }
 }
diff --git a/test/SemaTemplate/instantiate-member-expr.cpp b/test/SemaTemplate/instantiate-member-expr.cpp
index a31569a0c3..6ba94b28df 100644
--- a/test/SemaTemplate/instantiate-member-expr.cpp
+++ b/test/SemaTemplate/instantiate-member-expr.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify %s -pedantic
 template<typename T>
 struct S {
  S() { }
@@ -66,3 +66,18 @@ namespace test2 {
 
   template class B<int>;
 }
+
+namespace PR14124 {
+  template<typename T> struct S {
+    int value;
+  };
+  template<typename T> void f() { S<T>::value; } // expected-error {{invalid use of non-static data member 'value'}}
+  template void f<int>(); // expected-note {{in instantiation of}}
+
+  struct List { List *next; };
+  template<typename T, T *(T::*p) = &T::next> struct A {};
+  A<List> a; // ok
+  void operator&(struct Whatever);
+  template<typename T, T *(T::*p) = &T::next> struct B {};
+  B<List> b; // still ok
+}