[c++20] P0515R3: Parsing support and basic AST construction for operator <=>.

Adding the new enumerator forced a bunch more changes into this patch than I
would have liked. The -Wtautological-compare warning was extended to properly
check the new comparison operator, clang-format needed updating because it uses
precedence levels as weights for determining where to break lines (and several
operators increased their precedence levels with this change), thread-safety
analysis needed changes to build its own IL properly for the new operator.

All "real" semantic checking for this operator has been deferred to a future
patch. For now, we use the relational comparison rules and arbitrarily give
the builtin form of the operator a return type of 'void'.

llvm-svn: 320707

1 files changed, 1 insertions, 0 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index e899b7ca164..9c9eeb79b40 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -10471,6 +10471,7 @@ static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
     case BO_AndAssign:
     case BO_XorAssign:
     case BO_OrAssign:
+    case BO_Cmp: // FIXME: Re-enable once we can evaluate this.
       // C99 6.6/3 allows assignments within unevaluated subexpressions of
       // constant expressions, but they can never be ICEs because an ICE cannot
       // contain an lvalue operand.