[PATCH] D153296: [AST] Stop evaluate constant expression if the condition expression which in switch statement contains errors

[Yurong via Phabricator via cfe-commits]

yronglin updated this revision to Diff 533738.
yronglin marked an inline comment as done.
yronglin added a comment.

Update wording.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D153296/new/

https://reviews.llvm.org/D153296

Files:
  clang/docs/ReleaseNotes.rst
  clang/lib/AST/ExprConstant.cpp
  clang/test/SemaCXX/switch.cpp


Index: clang/test/SemaCXX/switch.cpp
===================================================================
--- clang/test/SemaCXX/switch.cpp
+++ clang/test/SemaCXX/switch.cpp
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 %s
 
 void test() {
   bool x = true;
@@ -146,3 +147,17 @@
 }
 
 } // namespace EmptyEnum
+
+#if __cplusplus >= 201703L
+constexpr int foo(unsigned char c) {
+    switch (unknown_value) { // expected-error {{use of undeclared identifier}}
+    case 0:
+        return 7;
+    default:
+        break;
+    }
+    return 0;
+}
+
+static_assert(foo('d')); // expected-error {{static assertion expression is not an integral constant expression}}
+#endif
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -4889,6 +4889,9 @@
 
 static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) {
   assert(E->isValueDependent());
+  // Stop evaluating if expression contains errors.
+  if (E->containsErrors())
+    return false;
   if (Info.noteSideEffect())
     return true;
   assert(E->containsErrors() && "valid value-dependent expression should never "
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -520,6 +520,9 @@
   type by the default argument promotions, and thus this is UB. Clang's
   behavior now matches GCC's behavior in C++.
   (`#38717 <https://github.com/llvm/llvm-project/issues/38717>_`).
+- Stop evaluating a constant expression if the condition expression which in 
+  switch statement contains errors.
+  (`#63453 <https://github.com/llvm/llvm-project/issues/63453>_`)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


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