[PATCH] D72621: PR44514: Fix recovery from noexcept with non-convertible expressions

[Erich Keane via Phabricator via cfe-commits]

erichkeane created this revision.
erichkeane added a reviewer: aaron.ballman.
Herald added a project: clang.

We currently treat noexcept(not-convertible-to-bool) as 'none', which
results in the typeloc info being a different size, and causing an
assert later on in the process.  In order to make recovery less
destructive, replace this with noexcept(false) and a constructed 'false'
expression.


Repository:
  rC Clang

https://reviews.llvm.org/D72621

Files:
  clang/lib/Sema/SemaExceptionSpec.cpp
  clang/test/SemaCXX/cxx0x-noexcept-expression.cpp


Index: clang/test/SemaCXX/cxx0x-noexcept-expression.cpp
===================================================================
--- clang/test/SemaCXX/cxx0x-noexcept-expression.cpp
+++ clang/test/SemaCXX/cxx0x-noexcept-expression.cpp
@@ -75,3 +75,8 @@
   static_assert(!noexcept((int(*)[b ? throw : 42])0), "");
   static_assert(!noexcept((int(*)[b ? throw : 42]){0}), "");
 }
+
+struct pr_44514 {
+  // expected-error at +1{{value of type 'void' is not contextually convertible to 'bool'}}
+  void foo(void) const &noexcept(f());
+};
Index: clang/lib/Sema/SemaExceptionSpec.cpp
===================================================================
--- clang/lib/Sema/SemaExceptionSpec.cpp
+++ clang/lib/Sema/SemaExceptionSpec.cpp
@@ -81,8 +81,16 @@
                                    ExceptionSpecificationType &EST) {
   // FIXME: This is bogus, a noexcept expression is not a condition.
   ExprResult Converted = CheckBooleanCondition(NoexceptLoc, NoexceptExpr);
-  if (Converted.isInvalid())
-    return Converted;
+  if (Converted.isInvalid()) {
+    EST = EST_NoexceptFalse;
+
+    // Fill in an expression of 'false' as a fixup.
+    auto *BoolExpr = new (Context)
+        CXXBoolLiteralExpr(false, Context.BoolTy, NoexceptExpr->getBeginLoc());
+    llvm::APSInt Value{1};
+    Value = 0;
+    return ConstantExpr::Create(Context, BoolExpr, APValue{Value});
+  }
 
   if (Converted.get()->isValueDependent()) {
     EST = EST_DependentNoexcept;


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