[c++20] Add rewriting from comparison operators to <=> / ==.

This adds support for rewriting <, >, <=, and >= to a normal or reversed
call to operator<=>, for rewriting != to a normal or reversed call to
operator==, and for rewriting <=> and == to reversed forms of those same
operators.

Note that this is a breaking change for various C++17 code patterns,
including some in use in LLVM. The most common patterns (where an
operator== becomes ambiguous with a reversed form of itself) are still
accepted under this patch, as an extension (with a warning). I'm hopeful
that we can get the language rules fixed before C++20 ships, and the
extension warning is aimed primarily at providing data to inform that
decision.

llvm-svn: 375306

1 files changed, 2 insertions, 2 deletions

diff --git a/clang/lib/AST/ExprCXX.cpp b/clang/lib/AST/ExprCXX.cpp
index 0b0d3c6880a..904928bdf28 100644
--- a/clang/lib/AST/ExprCXX.cpp
+++ b/clang/lib/AST/ExprCXX.cpp
@@ -79,7 +79,7 @@ CXXRewrittenBinaryOperator::getDecomposedForm() const {
     Result.RHS = BO->getRHS();
     Result.InnerBinOp = BO;
   } else if (auto *BO = dyn_cast<CXXOperatorCallExpr>(E)) {
-    assert(!SkippedNot || BO->getOperator() == OO_Equal);
+    assert(!SkippedNot || BO->getOperator() == OO_EqualEqual);
     assert(BO->isInfixBinaryOp());
     switch (BO->getOperator()) {
     case OO_Less: Result.Opcode = BO_LT; break;
@@ -107,7 +107,7 @@ CXXRewrittenBinaryOperator::getDecomposedForm() const {
     return Result;
 
   // Otherwise, we expect a <=> to now be on the LHS.
-  E = Result.InnerBinOp->IgnoreImplicit();
+  E = Result.LHS->IgnoreImplicit();
   if (auto *BO = dyn_cast<BinaryOperator>(E)) {
     assert(BO->getOpcode() == BO_Cmp);
     Result.LHS = BO->getLHS();