[PATCH] D113517: Correct handling of the 'throw()' exception specifier in C++17.

[James Y Knight via Phabricator via cfe-commits]

jyknight created this revision.
jyknight added a reviewer: aaron.ballman.
jyknight requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Per C++17 [except.spec], 'throw()' has become equivalent to
'noexcept', and should therefore call std::terminate, not
std::unexpected.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D113517

Files:
  clang/lib/CodeGen/CGException.cpp
  clang/test/CXX/except/except.spec/p9-dynamic.cpp


Index: clang/test/CXX/except/except.spec/p9-dynamic.cpp
===================================================================
--- clang/test/CXX/except/except.spec/p9-dynamic.cpp
+++ clang/test/CXX/except/except.spec/p9-dynamic.cpp
@@ -1,12 +1,26 @@
-// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - -fcxx-exceptions -fexceptions | FileCheck %s
+// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - -fcxx-exceptions -fexceptions | FileCheck %s --check-prefixes=CHECK,CHECK-PRE17
+// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -std=c++17 -Wno-dynamic-exception-spec -emit-llvm -o - -fcxx-exceptions -fexceptions | FileCheck %s --check-prefixes=CHECK,CHECK-17
 
 void external();
 
+// CHECK-LABEL: _Z6targetv(
+// CHECK: invoke void @_Z8externalv()
+// CHECK:      landingpad { i8*, i32 }
+// CHECK-NEXT:   filter [1 x i8*] [i8* bitcast (i8** @_ZTIi to i8*)]
+// CHECK:      call void @__cxa_call_unexpected
 void target() throw(int)
 {
-  // CHECK: invoke void @_Z8externalv()
   external();
 }
-// CHECK:      landingpad { i8*, i32 }
-// CHECK-NEXT:   filter [1 x i8*] [i8* bitcast (i8** @_ZTIi to i8*)]
-// CHECK:      call void @__cxa_call_unexpected
+
+// CHECK-LABEL: _Z7target2v(
+// CHECK: invoke void @_Z8externalv()
+// CHECK:            landingpad { i8*, i32 }
+// CHECK-PRE17-NEXT:   filter [0 x i8*] zeroinitializer
+// CHECK-17-NEXT:      catch i8* null
+// CHECK-PRE17:      call void @__cxa_call_unexpected
+// CHECK-17:         call void @__clang_call_terminate
+void target2() throw()
+{
+  external();
+}
Index: clang/lib/CodeGen/CGException.cpp
===================================================================
--- clang/lib/CodeGen/CGException.cpp
+++ clang/lib/CodeGen/CGException.cpp
@@ -477,7 +477,10 @@
     return;
 
   ExceptionSpecificationType EST = Proto->getExceptionSpecType();
-  if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot) {
+  // In C++17 and later, 'throw()' aka EST_DynamicNone is treated the same way
+  // as noexcept. In earlier standards, it is handled separately, below.
+  if ((getLangOpts().CPlusPlus17 || EST != EST_DynamicNone) &&
+      Proto->canThrow() == CT_Cannot) {
     // noexcept functions are simple terminate scopes.
     if (!getLangOpts().EHAsynch) // -EHa: HW exception still can occur
       EHStack.pushTerminate();
@@ -580,7 +583,8 @@
     return;
 
   ExceptionSpecificationType EST = Proto->getExceptionSpecType();
-  if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot &&
+  if ((getLangOpts().CPlusPlus17 || EST != EST_DynamicNone) &&
+      Proto->canThrow() == CT_Cannot &&
       !EHStack.empty() /* possible empty when under async exceptions */) {
     EHStack.popTerminate();
   } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {


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