Fix some cases where a CK_IntegralCast was being used to convert an lvalue to an

rvalue. An assertion to catch this is in ImpCastExprToType will follow, but
vector operations currently trip over this (due to omitting the usual arithmetic
conversions). Also add an assert to catch missing lvalue-to-rvalue conversions
on the LHS of ->.

llvm-svn: 143155

clang/lib/Sema/SemaExprMember.cpp

@@ -761,6 +761,7 @@ static MemberExpr *BuildMemberExpr(ASTContext &C, Expr *Base, bool isArrow,
                                    QualType Ty,
                                    ExprValueKind VK, ExprObjectKind OK,
                                    const TemplateArgumentListInfo *TemplateArgs = 0) {
+  assert((!isArrow || Base->isRValue()) && "-> base must be a pointer rvalue");
   return MemberExpr::Create(C, Base, isArrow, SS.getWithLocInContext(C),
                             Member, FoundDecl, MemberNameInfo,
                             TemplateArgs, Ty, VK, OK);

clang/lib/Sema/SemaStmt.cpp

@@ -639,6 +639,9 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
 
       // If the LHS is not the same type as the condition, insert an implicit
       // cast.
+      // FIXME: In C++11, the value is a converted constant expression of the
+      // promoted type of the switch condition.
+      Lo = DefaultLvalueConversion(Lo).take();
       Lo = ImpCastExprToType(Lo, CondType, CK_IntegralCast).take();
       CS->setLHS(Lo);
 
@@ -716,8 +719,11 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
                                            Hi->getLocStart(),
                                            diag::warn_case_value_overflow);
 
-        // If the LHS is not the same type as the condition, insert an implicit
+        // If the RHS is not the same type as the condition, insert an implicit
         // cast.
+        // FIXME: In C++11, the value is a converted constant expression of the
+        // promoted type of the switch condition.
+        Hi = DefaultLvalueConversion(Hi).take();
         Hi = ImpCastExprToType(Hi, CondType, CK_IntegralCast).take();
         CR->setRHS(Hi);
 

clang/lib/Sema/SemaTemplate.cpp

@@ -3743,8 +3743,16 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
   //        enumeration type, integral promotions (4.5) and integral
   //        conversions (4.7) are applied.
   QualType ParamType = InstantiatedParamType;
-  QualType ArgType = Arg->getType();
   if (ParamType->isIntegralOrEnumerationType()) {
+    // FIXME: In C++11, the argument is a converted constant expression of the
+    // type of the template parameter.
+    ExprResult ArgResult = DefaultLvalueConversion(Arg);
+    if (ArgResult.isInvalid())
+      return ExprError();
+    Arg = ArgResult.take();
+
+    QualType ArgType = Arg->getType();
+
     // C++ [temp.arg.nontype]p1:
     //   A template-argument for a non-type, non-template
     //   template-parameter shall be one of:
@@ -3868,6 +3876,7 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
     return Owned(Arg);
   }
 
+  QualType ArgType = Arg->getType();
   DeclAccessPair FoundResult; // temporary for ResolveOverloadedFunction
 
   // C++0x [temp.arg.nontype]p5 bullets 2, 4 and 6 permit conversion

clang/test/SemaCXX/constant-expression-cxx11.cpp

@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+
+template<typename T> constexpr T id(const T &t) { return t; }
+
+struct MemberZero {
+  constexpr int zero() { return 0; }
+};
+
+namespace TemplateArgumentConversion {
+  template<int n> struct IntParam {};
+
+  using IntParam0 = IntParam<0>;
+  // FIXME: This should be accepted once we do constexpr function invocation.
+  using IntParam0 = IntParam<id(0)>; // expected-error {{not an integral constant expression}}
+  using IntParam0 = IntParam<MemberZero().zero>; // expected-error {{did you mean to call it with no arguments?}} expected-error {{not an integral constant expression}}
+}
+
+namespace CaseStatements {
+  void f(int n) {
+    switch (n) {
+    // FIXME: Produce the 'add ()' fixit for this.
+    case MemberZero().zero: // desired-error {{did you mean to call it with no arguments?}} expected-error {{not an integer constant expression}}
+    // FIXME: This should be accepted once we do constexpr function invocation.
+    case id(1): // expected-error {{not an integer constant expression}}
+      return;
+    }
+  }
+}