From d5f3a0fde43bca9f3738aed931b0f13ca73a9f11 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Tue, 19 May 2009 20:13:50 +0000
Subject: [PATCH] Fix handling of the GNU "t ? : f" extension to the
 conditional operator in C++, and verify that template instantiation for the
 condition operator does the right thing.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72127 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/Expr.cpp                         |  8 ++++----
 lib/Sema/SemaTemplateInstantiateExpr.cpp | 16 ++++++++--------
 test/SemaTemplate/instantiate-expr-3.cpp | 18 ++++++++++++++++++
 3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 6bafdf278d..2df76a2904 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -828,16 +828,16 @@ Expr::isLvalueResult Expr::isLvalueInternal(ASTContext &Ctx) const {
     // casts should be wrapped by ImplicitCastExprs. There's just the special
     // case involving throws to work out.
     const ConditionalOperator *Cond = cast<ConditionalOperator>(this);
-    Expr *LHS = Cond->getLHS();
-    Expr *RHS = Cond->getRHS();
+    Expr *True = Cond->getTrueExpr();
+    Expr *False = Cond->getFalseExpr();
     // C++0x 5.16p2
     //   If either the second or the third operand has type (cv) void, [...]
     //   the result [...] is an rvalue.
-    if (LHS->getType()->isVoidType() || RHS->getType()->isVoidType())
+    if (True->getType()->isVoidType() || False->getType()->isVoidType())
       return LV_InvalidExpression;
 
     // Both sides must be lvalues for the result to be an lvalue.
-    if (LHS->isLvalue(Ctx) != LV_Valid || RHS->isLvalue(Ctx) != LV_Valid)
+    if (True->isLvalue(Ctx) != LV_Valid || False->isLvalue(Ctx) != LV_Valid)
       return LV_InvalidExpression;
 
     // That's it.
diff --git a/lib/Sema/SemaTemplateInstantiateExpr.cpp b/lib/Sema/SemaTemplateInstantiateExpr.cpp
index 9dda383342..2589e301e0 100644
--- a/lib/Sema/SemaTemplateInstantiateExpr.cpp
+++ b/lib/Sema/SemaTemplateInstantiateExpr.cpp
@@ -427,13 +427,13 @@ TemplateExprInstantiator::VisitConditionalOperator(ConditionalOperator *E) {
   if (Cond.isInvalid())
     return SemaRef.ExprError();
 
-  // FIXME: use getLHS() and cope with NULLness
-  Sema::OwningExprResult True = Visit(E->getTrueExpr());
-  if (True.isInvalid())
+  Sema::OwningExprResult LHS = SemaRef.InstantiateExpr(E->getLHS(), 
+                                                       TemplateArgs);
+  if (LHS.isInvalid())
     return SemaRef.ExprError();
 
-  Sema::OwningExprResult False = Visit(E->getFalseExpr());
-  if (False.isInvalid())
+  Sema::OwningExprResult RHS = Visit(E->getRHS());
+  if (RHS.isInvalid())
     return SemaRef.ExprError();
 
   if (!E->isTypeDependent()) { 
@@ -442,15 +442,15 @@ TemplateExprInstantiator::VisitConditionalOperator(ConditionalOperator *E) {
     // Instead, we just build the new conditional operator call expression.
     return SemaRef.Owned(new (SemaRef.Context) ConditionalOperator(
                                                            Cond.takeAs<Expr>(),
-                                                           True.takeAs<Expr>(), 
-                                                           False.takeAs<Expr>(),
+                                                           LHS.takeAs<Expr>(), 
+                                                           RHS.takeAs<Expr>(),
                                                            E->getType()));
   }
 
 
   return SemaRef.ActOnConditionalOp(/*FIXME*/E->getCond()->getLocEnd(),
                                     /*FIXME*/E->getFalseExpr()->getLocStart(),
-                                    move(Cond), move(True), move(False));
+                                    move(Cond), move(LHS), move(RHS));
 }
 
 Sema::OwningExprResult 
diff --git a/test/SemaTemplate/instantiate-expr-3.cpp b/test/SemaTemplate/instantiate-expr-3.cpp
index 892f649ef7..7f54c5de3c 100644
--- a/test/SemaTemplate/instantiate-expr-3.cpp
+++ b/test/SemaTemplate/instantiate-expr-3.cpp
@@ -1,5 +1,8 @@
 // RUN: clang-cc -fsyntax-only -verify %s
 
+// ---------------------------------------------------------------------
+// Imaginary literals
+// ---------------------------------------------------------------------
 template<typename T>
 struct ImaginaryLiteral0 {
   void f(T &x) {
@@ -10,6 +13,9 @@ struct ImaginaryLiteral0 {
 template struct ImaginaryLiteral0<_Complex float>;
 template struct ImaginaryLiteral0<int*>; // expected-note{{instantiation}}
 
+// ---------------------------------------------------------------------
+// Compound assignment operator
+// ---------------------------------------------------------------------
 namespace N1 {
   struct X { };
 
@@ -38,3 +44,15 @@ template struct N2::PlusEquals0<N1::X, long, long&>;
 template struct N2::PlusEquals0<N3::Y, long, short&>;
 template struct N2::PlusEquals0<int, int, int&>;
 template struct N2::PlusEquals0<N3::Y, int, short&>; // expected-note{{instantiation}}
+
+// ---------------------------------------------------------------------
+// Conditional operator
+// ---------------------------------------------------------------------
+template<typename T, typename U, typename Result>
+struct Conditional0 {
+  void f(T t, U u) {
+    Result result = t? : u;
+  }
+};
+
+template struct Conditional0<int, int, int>;
-- 
2.40.0