[clang][Interp] Handle CXXNoexceptExprs

[cor3ntin]

clang/test/AST/Interp/literals.cpp

914–922

Can you either add tests with explicit expressions in the no except, or see if you can enable one of the existing test files?

[tbaeder]

clang/test/AST/Interp/literals.cpp

914–922

Turns out I can.

[tbaeder]

clang/lib/AST/Interp/ByteCodeExprGen.cpp

1015

Looks like this is wrong.

[tbaeder]

Always ignore the operand expression.

[cor3ntin]

LGTM, thanks

clang/lib/AST/Interp/ByteCodeExprGen.h

public:
   bool VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr *E);
   bool VisitCXXTemporaryObjectExpr(const CXXTemporaryObjectExpr *E);
   bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
   bool VisitTypeTraitExpr(const TypeTraitExpr *E);
   bool VisitLambdaExpr(const LambdaExpr *E);
   bool VisitPredefinedExpr(const PredefinedExpr *E);
   bool VisitCXXThrowExpr(const CXXThrowExpr *E);
   bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E);
+  bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E);
 
 protected:
   bool visitExpr(const Expr *E) override;
   bool visitDecl(const VarDecl *VD) override;
 
 protected:
   /// Emits scope cleanup instructions.
   void emitCleanup();

clang/lib/AST/Interp/ByteCodeExprGen.cpp

 bool ByteCodeExprGen<Emitter>::VisitCXXReinterpretCastExpr(
     const CXXReinterpretCastExpr *E) {
   if (!this->discard(E->getSubExpr()))
     return false;
 
   return this->emitInvalidCast(CastKind::Reinterpret, E);
 }
 
+template <class Emitter>
+bool ByteCodeExprGen<Emitter>::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) {
+  assert(E->getType()->isBooleanType());
+
+  if (DiscardResult)
+    return true;
+  return this->emitConstBool(E->getValue(), E);
+}
+
 template <class Emitter> bool ByteCodeExprGen<Emitter>::discard(const Expr *E) {
   if (E->containsErrors())
     return false;
 
   OptionScope<Emitter> Scope(this, /*NewDiscardResult=*/true);
   return this->Visit(E);
 }
 

clang/test/AST/Interp/literals.cpp

__extension__ __FUNCTION__; // ref-warning {{result unused}} \
                                 // expected-warning {{result unused}}
     return __FUNCTION__[index];
   }
   static_assert(heh(0) == 'h', "");
   static_assert(heh(1) == 'e', "");
   static_assert(heh(2) == 'h', "");
 #endif
 }
+
+namespace NE {
+  constexpr int foo() noexcept {
+    return 1;
+  }
+  static_assert(noexcept(foo()), "");
+  constexpr int foo2() {
+    return 1;
+  }
+  static_assert(!noexcept(foo2()), "");
+
+#if __cplusplus > 201402L
+  constexpr int a() {
+    int b = 0;
+    (void)noexcept(++b); // expected-warning {{expression with side effects has no effect in an unevaluated context}} \
+                         // ref-warning {{expression with side effects has no effect in an unevaluated context}}
+
+    return b;
+  }
+  static_assert(a() == 0, "");
+#endif
+}

clang/test/SemaCXX/cxx0x-noexcept-expression.cpp

 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++2a %s -fexceptions -fcxx-exceptions -Wno-unevaluated-expression
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++2a %s -fexceptions -fcxx-exceptions -Wno-unevaluated-expression -fexperimental-new-constant-interpreter
 
 void f(); // expected-note {{possible target for call}}
 void f(int); // expected-note {{possible target for call}}
 
 void g() {
   bool b = noexcept(f); // expected-error {{reference to overloaded function could not be resolved; did you mean to call it with no arguments?}}
   bool b2 = noexcept(f(0));
 }