[c++1z] P0003R5: Removing dynamic exception specifications.

We continue to support dynamic exception specifications in C++1z as an
extension, but produce an error-by-default warning when we encounter one. This
allows users to opt back into the feature with a warning flag, and implicitly
opts system headers back into the feature should they happen to use it.

There is one semantic change implied by P0003R5 but not implemented here:
violating a throw() exception specification should now call std::terminate
directly instead of calling std::unexpected(), but since P0003R5 also removes
std::unexpected() and std::set_unexpected, and the default unexpected handler
calls std::terminate(), a conforming C++1z program cannot tell that we are
still calling it. The upside of this strategy is perfect backwards
compatibility; the downside is that we don't get the more efficient 'noexcept'
codegen for 'throw()'.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@289019 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/DiagnosticGroups.td

@@ -97,6 +97,8 @@ def UnavailableDeclarations : DiagGroup<"unavailable-declarations">;
 def UnguardedAvailability : DiagGroup<"unguarded-availability">;
 // partial-availability is an alias of unguarded-availability.
 def : DiagGroup<"partial-availability", [UnguardedAvailability]>;
+def DeprecatedDynamicExceptionSpec
+    : DiagGroup<"deprecated-dynamic-exception-spec">;
 def DeprecatedImplementations :DiagGroup<"deprecated-implementations">;
 def DeprecatedIncrementBool : DiagGroup<"deprecated-increment-bool">;
 def DeprecatedRegister : DiagGroup<"deprecated-register">;
@@ -105,11 +107,15 @@ def DeprecatedWritableStr : DiagGroup<"deprecated-writable-strings",
 // FIXME: Why is DeprecatedImplementations not in this group?
 def Deprecated : DiagGroup<"deprecated", [DeprecatedAttributes,
                                           DeprecatedDeclarations,
+                                          DeprecatedDynamicExceptionSpec,
                                           DeprecatedIncrementBool,
                                           DeprecatedRegister,
                                           DeprecatedWritableStr]>,
                  DiagCategory<"Deprecations">;
 
+def DynamicExceptionSpec
+    : DiagGroup<"dynamic-exception-spec", [DeprecatedDynamicExceptionSpec]>;
+
 def LibLTO : DiagGroup<"liblto">;
 def : DiagGroup<"disabled-optimization">;
 def : DiagGroup<"discard-qual">;

include/clang/Basic/DiagnosticSemaKinds.td

@@ -483,9 +483,12 @@ def warn_access_decl_deprecated : Warning<
 def err_access_decl : Error<
   "ISO C++11 does not allow access declarations; "
   "use using declarations instead">;
+def ext_dynamic_exception_spec : ExtWarn<
+  "ISO C++1z does not allow dynamic exception specifications">,
+  InGroup<DynamicExceptionSpec>, DefaultError;
 def warn_exception_spec_deprecated : Warning<
   "dynamic exception specifications are deprecated">,
-  InGroup<Deprecated>, DefaultIgnore;
+  InGroup<DeprecatedDynamicExceptionSpec>, DefaultIgnore;
 def note_exception_spec_deprecated : Note<"use '%0' instead">;
 def warn_deprecated_copy_operation : Warning<
   "definition of implicit copy %select{constructor|assignment operator}1 "

lib/Parse/ParseDeclCXX.cpp

@@ -3513,7 +3513,11 @@ static void diagnoseDynamicExceptionSpecification(
     Parser &P, SourceRange Range, bool IsNoexcept) {
   if (P.getLangOpts().CPlusPlus11) {
     const char *Replacement = IsNoexcept ? "noexcept" : "noexcept(false)";
-    P.Diag(Range.getBegin(), diag::warn_exception_spec_deprecated) << Range;
+    P.Diag(Range.getBegin(),
+           P.getLangOpts().CPlusPlus1z && !IsNoexcept
+               ? diag::ext_dynamic_exception_spec
+               : diag::warn_exception_spec_deprecated)
+        << Range;
     P.Diag(Range.getBegin(), diag::note_exception_spec_deprecated)
       << Replacement << FixItHint::CreateReplacement(Range, Replacement);
   }

test/CXX/conv/conv.fctptr/p1.cpp

@@ -35,8 +35,8 @@ static_assert(q == &S::f);
 
 
 namespace std_example {
-  void (*p)() throw(int);
-  void (**pp)() noexcept = &p; // expected-error {{cannot initialize a variable of type 'void (**)() noexcept' with an rvalue of type 'void (**)() throw(int)'}}
+  void (*p)();
+  void (**pp)() noexcept = &p; // expected-error {{cannot initialize a variable of type 'void (**)() noexcept' with an rvalue of type 'void (**)()'}}
 
   struct S { typedef void (*p)(); operator p(); }; // expected-note {{candidate}}
   void (*q)() noexcept = S(); // expected-error {{no viable conversion from 'std_example::S' to 'void (*)() noexcept'}}

test/CXX/drs/dr0xx.cpp

@@ -276,9 +276,9 @@ namespace dr23 { // dr23: yes
 
 namespace dr25 { // dr25: yes
   struct A {
-    void f() throw(int);
+    void f() throw(int); // expected-error 0-1{{ISO C++1z does not allow}} expected-note 0-1{{use 'noexcept}}
   };
-  void (A::*f)() throw (int);
+  void (A::*f)() throw (int); // expected-error 0-1{{ISO C++1z does not allow}} expected-note 0-1{{use 'noexcept}}
   void (A::*g)() throw () = f;
 #if __cplusplus <= 201402L
   // expected-error@-2 {{is not superset of source}}
@@ -286,7 +286,7 @@ namespace dr25 { // dr25: yes
   // expected-error@-4 {{different exception specifications}}
 #endif
   void (A::*g2)() throw () = 0;
-  void (A::*h)() throw (int, char) = f;
+  void (A::*h)() throw (int, char) = f; // expected-error 0-1{{ISO C++1z does not allow}} expected-note 0-1{{use 'noexcept}}
   void (A::*i)() throw () = &A::f;
 #if __cplusplus <= 201402L
   // expected-error@-2 {{is not superset of source}}
@@ -294,7 +294,7 @@ namespace dr25 { // dr25: yes
   // expected-error@-4 {{different exception specifications}}
 #endif
   void (A::*i2)() throw () = 0;
-  void (A::*j)() throw (int, char) = &A::f;
+  void (A::*j)() throw (int, char) = &A::f; // expected-error 0-1{{ISO C++1z does not allow}} expected-note 0-1{{use 'noexcept}}
   void x() {
     g2 = f;
 #if __cplusplus <= 201402L
@@ -1033,14 +1033,14 @@ namespace dr91 { // dr91: yes
 }
 
 namespace dr92 { // dr92: 4.0 c++17
-  void f() throw(int, float);
-  void (*p)() throw(int) = &f;
+  void f() throw(int, float); // expected-error 0-1{{ISO C++1z does not allow}} expected-note 0-1{{use 'noexcept}}
+  void (*p)() throw(int) = &f; // expected-error 0-1{{ISO C++1z does not allow}} expected-note 0-1{{use 'noexcept}}
 #if __cplusplus <= 201402L
   // expected-error@-2 {{target exception specification is not superset of source}}
 #else
   // expected-warning@-4 {{target exception specification is not superset of source}}
 #endif
-  void (*q)() throw(int);
+  void (*q)() throw(int); // expected-error 0-1{{ISO C++1z does not allow}} expected-note 0-1{{use 'noexcept}}
   void (**pp)() throw() = &q;
 #if __cplusplus <= 201402L
   // expected-error@-2 {{exception specifications are not allowed}}
@@ -1064,7 +1064,7 @@ namespace dr92 { // dr92: 4.0 c++17
   // expected-error@-2 {{not implicitly convertible}}
 #endif
 
-  template<void() throw(int)> struct Y {};
+  template<void() throw(int)> struct Y {}; // expected-error 0-1{{ISO C++1z does not allow}} expected-note 0-1{{use 'noexcept}}
   Y<&h> yp; // ok
 }
 

test/CXX/drs/dr13xx.cpp

@@ -6,7 +6,7 @@
 namespace dr1330 { // dr1330: 4.0 c++11
   // exception-specifications are parsed in a context where the class is complete.
   struct A {
-    void f() throw(T) {}
+    void f() throw(T) {} // expected-error 0-1{{C++1z}} expected-note 0-1{{noexcept}}
     struct T {};
 
 #if __cplusplus >= 201103L
@@ -16,7 +16,7 @@ namespace dr1330 { // dr1330: 4.0 c++11
 #endif
   };
 
-  void (A::*af1)() throw(A::T) = &A::f;
+  void (A::*af1)() throw(A::T) = &A::f; // expected-error 0-1{{C++1z}} expected-note 0-1{{noexcept}}
   void (A::*af2)() throw() = &A::f; // expected-error-re {{{{not superset|different exception spec}}}}
 
 #if __cplusplus >= 201103L
@@ -26,7 +26,7 @@ namespace dr1330 { // dr1330: 4.0 c++11
   // Likewise, they're instantiated separately from an enclosing class template.
   template<typename U>
   struct B {
-    void f() throw(T, typename U::type) {}
+    void f() throw(T, typename U::type) {} // expected-error 0-1{{C++1z}} expected-note 0-1{{noexcept}}
     struct T {};
 
 #if __cplusplus >= 201103L
@@ -43,7 +43,7 @@ namespace dr1330 { // dr1330: 4.0 c++11
     static const int value = true;
   };
 
-  void (B<P>::*bpf1)() throw(B<P>::T, int) = &B<P>::f;
+  void (B<P>::*bpf1)() throw(B<P>::T, int) = &B<P>::f; // expected-error 0-1{{C++1z}} expected-note 0-1{{noexcept}}
 #if __cplusplus < 201103L
   // expected-error@-2 {{not superset}}
   // FIXME: We only delay instantiation in C++11 onwards. In C++98, something
@@ -54,7 +54,7 @@ namespace dr1330 { // dr1330: 4.0 c++11
   // the "T has not yet been instantiated" error here, rather than giving
   // confusing errors later on.
 #endif
-  void (B<P>::*bpf2)() throw(int) = &B<P>::f;
+  void (B<P>::*bpf2)() throw(int) = &B<P>::f; // expected-error 0-1{{C++1z}} expected-note 0-1{{noexcept}}
 #if __cplusplus <= 201402L
   // expected-error@-2 {{not superset}}
 #else
@@ -75,6 +75,9 @@ namespace dr1330 { // dr1330: 4.0 c++11
 #endif
 
   template<typename T> int f() throw(typename T::error) { return 0; } // expected-error 1-4{{prior to '::'}} expected-note 0-1{{instantiation of}}
+#if __cplusplus > 201402L
+    // expected-error@-2 0-1{{C++1z}} expected-note@-2 0-1{{noexcept}}
+#endif
   // An exception-specification is needed even if the function is only used in
   // an unevaluated operand.
   int f1 = sizeof(f<int>()); // expected-note {{instantiation of}}
@@ -86,6 +89,9 @@ namespace dr1330 { // dr1330: 4.0 c++11
 
   template<typename T> struct C {
     C() throw(typename T::type); // expected-error 1-2{{prior to '::'}}
+#if __cplusplus > 201402L
+    // expected-error@-2 0-1{{C++1z}} expected-note@-2 0-1{{noexcept}}
+#endif
   };
   struct D : C<void> {}; // ok
 #if __cplusplus < 201103L

test/CXX/drs/dr1xx.cpp

@@ -239,6 +239,7 @@ namespace dr125 {
 }
 
 namespace dr126 { // dr126: no
+#if __cplusplus <= 201402L
   struct C {};
   struct D : C {};
   struct E : private C { friend class A; friend class B; };
@@ -311,12 +312,15 @@ namespace dr126 { // dr126: no
     virtual void y() throw(int*); // ok
     virtual void z() throw(long); // expected-error {{more lax}}
   };
+#else
+  void f() throw(int); // expected-error {{ISO C++1z does not allow}} expected-note {{use 'noexcept}}
+#endif
 }
 
 namespace dr127 { // dr127: yes
   __extension__ typedef __decltype(sizeof(0)) size_t;
   template<typename T> struct A {
-    A() throw(int);
+    A() { throw 0; }
     void *operator new(size_t, const char * = 0);
     void operator delete(void *, const char *) { T::error; } // expected-error 2{{no members}}
     void operator delete(void *) { T::error; }

test/CXX/drs/dr2xx.cpp

@@ -983,6 +983,9 @@ namespace dr289 { // dr289: yes
 
 namespace dr294 { // dr294: no
   void f() throw(int);
+#if __cplusplus > 201402L
+    // expected-error@-2 {{ISO C++1z does not allow}} expected-note@-2 {{use 'noexcept}}
+#endif
   int main() {
     (void)static_cast<void (*)() throw()>(f); // FIXME: ill-formed in C++14 and before
 #if __cplusplus > 201402L
@@ -992,12 +995,20 @@ namespace dr294 { // dr294: no
     // we reject it. In C++14 and before, this is ill-formed because an
     // exception-specification is not permitted in a type-id. In C++17, this is
     // valid because it's the inverse of a standard conversion sequence
-    // containing a function pointer conversion.
+    // containing a function pointer conversion. (Well, it's actually not valid
+    // yet, as a static_cast is not permitted to reverse a function pointer
+    // conversion, but that is being changed by core issue).
 #endif
     (void)static_cast<void (*)() throw(int)>(f); // FIXME: ill-formed in C++14 and before
+#if __cplusplus > 201402L
+    // expected-error@-2 {{ISO C++1z does not allow}} expected-note@-2 {{use 'noexcept}}
+#endif
 
     void (*p)() throw() = f; // expected-error-re {{{{not superset|different exception specification}}}}
     void (*q)() throw(int) = f;
+#if __cplusplus > 201402L
+    // expected-error@-2 {{ISO C++1z does not allow}} expected-note@-2 {{use 'noexcept}}
+#endif
   }
 }
 

test/CXX/drs/dr4xx.cpp

@@ -508,9 +508,18 @@ namespace dr437 { // dr437: sup 1308
   template<typename U> struct T : U {};
   struct S {
     void f() throw(S);
+#if __cplusplus > 201402L
+    // expected-error@-2 {{ISO C++1z does not allow}} expected-note@-2 {{use 'noexcept}}
+#endif
     void g() throw(T<S>);
+#if __cplusplus > 201402L
+    // expected-error@-2 {{ISO C++1z does not allow}} expected-note@-2 {{use 'noexcept}}
+#endif
     struct U;
     void h() throw(U);
+#if __cplusplus > 201402L
+    // expected-error@-2 {{ISO C++1z does not allow}} expected-note@-2 {{use 'noexcept}}
+#endif
     struct U {};
   };
 }

test/CXX/drs/dr5xx.cpp

@@ -953,6 +953,9 @@ namespace dr591 { // dr591: no
 namespace dr595 { // dr595: dup 1330
   template<class T> struct X {
     void f() throw(T) {}
+#if __cplusplus > 201402L
+    // expected-error@-2 {{ISO C++1z does not allow}} expected-note@-2 {{use 'noexcept}}
+#endif
   };
   struct S {
     X<S> xs;

test/CXX/expr/p13.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++1z -verify %s -fexceptions -fcxx-exceptions
+// RUN: %clang_cc1 -std=c++1z -verify %s -fexceptions -fcxx-exceptions -Wno-dynamic-exception-spec
 
 struct X {};
 struct Y : X {};

test/CodeGenCXX/mangle-exception-spec.cpp

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple=x86_64-apple-darwin9 | FileCheck %s --check-prefix CHECK --check-prefix CHECK-CXX11
-// RUN: %clang_cc1 -std=c++1z -emit-llvm %s -o - -triple=x86_64-apple-darwin9 | FileCheck %s --check-prefix CHECK --check-prefix CHECK-CXX17
+// RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple=x86_64-apple-darwin9 -Wno-dynamic-exception-spec | FileCheck %s --check-prefix CHECK --check-prefix CHECK-CXX11
+// RUN: %clang_cc1 -std=c++1z -emit-llvm %s -o - -triple=x86_64-apple-darwin9 -Wno-dynamic-exception-spec | FileCheck %s --check-prefix CHECK --check-prefix CHECK-CXX17
 
 // CHECK: define {{.*}} @_Z1aPFivE(
 void a(int() throw(int, float)) {}

test/SemaCXX/cxx1z-noexcept-function-type.cpp

@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -std=c++14 -verify -fexceptions -fcxx-exceptions %s
-// RUN: %clang_cc1 -std=c++1z -verify -fexceptions -fcxx-exceptions %s
+// RUN: %clang_cc1 -std=c++1z -verify -fexceptions -fcxx-exceptions %s -Wno-dynamic-exception-spec
 
 #if __cplusplus > 201402L
 

test/SemaCXX/deprecated.cpp

@@ -10,10 +10,14 @@
 void g() throw();
 void h() throw(int);
 void i() throw(...);
-#if __cplusplus >= 201103L
+#if __cplusplus > 201402L
 // expected-warning@-4 {{dynamic exception specifications are deprecated}} expected-note@-4 {{use 'noexcept' instead}}
-// expected-warning@-4 {{dynamic exception specifications are deprecated}} expected-note@-4 {{use 'noexcept(false)' instead}}
-// expected-warning@-4 {{dynamic exception specifications are deprecated}} expected-note@-4 {{use 'noexcept(false)' instead}}
+// expected-error@-4 {{ISO C++1z does not allow dynamic exception specifications}} expected-note@-4 {{use 'noexcept(false)' instead}}
+// expected-error@-4 {{ISO C++1z does not allow dynamic exception specifications}} expected-note@-4 {{use 'noexcept(false)' instead}}
+#elif __cplusplus >= 201103L
+// expected-warning@-8 {{dynamic exception specifications are deprecated}} expected-note@-8 {{use 'noexcept' instead}}
+// expected-warning@-8 {{dynamic exception specifications are deprecated}} expected-note@-8 {{use 'noexcept(false)' instead}}
+// expected-warning@-8 {{dynamic exception specifications are deprecated}} expected-note@-8 {{use 'noexcept(false)' instead}}
 #endif
 
 void stuff() {

www/cxx_status.html

@@ -740,7 +740,7 @@ as the draft C++1z standard evolves.
     <tr>
       <td>Removing deprecated dynamic exception specifications</td>
       <td><a href="http://wg21.link/p0003r5">P0003R5</a></td>
-      <td class="none" align="center">No</td>
+      <td class="svn" align="center">SVN</td>
     </tr>
     <tr>
       <td>Pack expansions in <em>using-declarations</em></td>