c++: Handle attributes on exception declarations [PR110345]

This is a continuation of the series for the ignorability of standard
attributes.

I've added a test for assume attribute diagnostics appertaining to various
entities (mostly invalid) and while doing that, I've discovered that
attributes on exception declarations were mostly ignored, this patch
adds the missing cp_decl_attributes call and also in the
cp_parser_type_specifier_seq case differentiates between attributes and
std_attributes to be able to differentiate between attributes which apply
to the declaration using type-specifier-seq and attributes after the type
specifiers.

2024-12-18  Jakub Jelinek  <jakub@redhat.com>

	PR c++/110345
	* parser.cc (cp_parser_type_specifier_seq): Chain cxx11_attribute_p
	attributes after any type specifier in the is_declaration case
	to std_attributes rather than attributes.  Set also ds_attribute
	or ds_std_attribute locations if not yet set.
	(cp_parser_exception_declaration): Pass &type_specifiers.attributes
	instead of NULL as last argument, call cp_decl_attributes.

	* g++.dg/cpp0x/attr-assume1.C: New test.

1 files changed, 151 insertions, 0 deletions

diff --git a/gcc/testsuite/g++.dg/cpp0x/attr-assume1.C b/gcc/testsuite/g++.dg/cpp0x/attr-assume1.C
new file mode 100644
index 0000000..4aee2a2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/attr-assume1.C
@@ -0,0 +1,151 @@
+// C++ 26 P2552R3 - On the ignorability of standard attributes
+// { dg-do compile { target c++11 } }
+
+int arr[2];
+struct S { int a, b; };
+S arr2[2];
+
+void
+foo (int n)
+{
+  [[assume (n > 0)]];
+  [[assume]];					// { dg-error "wrong number of arguments specified for 'assume' attribute" }
+  [[assume ("abc")]];
+  [[assume (1, 2, 3)]];				// { dg-error "wrong number of arguments specified for 'assume' attribute" }
+
+  [[assume (true)]] int x1;			// { dg-error "'assume' attribute ignored" }
+
+  auto a = [] [[assume (true)]] () {};		// { dg-error "'assume' attribute ignored" }
+  auto b = [] constexpr [[assume (true)]] {};	// { dg-error "'assume' attribute ignored" }
+						// { dg-error "parameter declaration before lambda declaration specifiers only optional with" "" { target c++20_down } .-1 }
+						// { dg-error "'constexpr' lambda only available with" "" { target c++14_down } .-2 }
+  auto c = [] noexcept [[assume (true)]] {};	// { dg-error "'assume' attribute ignored" }
+						// { dg-error "parameter declaration before lambda exception specification only optional with" "" { target c++20_down } .-1 }
+  auto d = [] () [[assume (true)]] {};		// { dg-error "'assume' attribute ignored" }
+  auto e = new int [n] [[assume (true)]];	// { dg-warning "attributes ignored on outermost array type in new expression" }
+  auto e2 = new int [n] [[assume (true)]] [42];	// { dg-warning "attributes ignored on outermost array type in new expression" }
+  auto f = new int [n][42] [[assume (true)]];	// { dg-error "'assume' attribute ignored" }
+  [[assume (true)]];
+  [[assume (true)]] {}				// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[assume (true)]] if (true) {}		// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[assume (true)]] while (false) {}		// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[assume (true)]] goto lab;			// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[assume (true)]] lab:;			// { dg-error "'assume' attribute ignored" }
+  [[assume (true)]] try {} catch (int) {}	// { dg-warning "attributes at the beginning of statement are ignored" }
+  if ([[assume (true)]] int x = 0) {}		// { dg-error "'assume' attribute ignored" }
+  switch (n)
+    {
+    [[assume (true)]] case 1:			// { dg-error "'assume' attribute ignored" }
+    [[assume (true)]] break;			// { dg-warning "attributes at the beginning of statement are ignored" }
+    [[assume (true)]] default:			// { dg-error "'assume' attribute ignored" }
+	 break;
+    }
+  for ([[assume (true)]] auto a : arr) {}	// { dg-error "'assume' attribute ignored" }
+  for ([[assume (true)]] auto [a, b] : arr2) {}	// { dg-error "'assume' attribute ignored" }
+						// { dg-error "structured bindings only available with" "" { target c++14_down } .-1 }
+  [[assume (true)]] asm ("");			// { dg-warning "attributes ignored on 'asm' declaration" }
+  try {} catch ([[assume (true)]] int x) {}	// { dg-error "'assume' attribute ignored" }
+  try {} catch ([[assume (true)]] int) {}	// { dg-error "'assume' attribute ignored" }
+  try {} catch (int [[assume (true)]] x) {}	// { dg-warning "attribute ignored" }
+  try {} catch (int [[assume (true)]]) {}	// { dg-warning "attribute ignored" }
+  try {} catch (int x [[assume (true)]]) {}	// { dg-error "'assume' attribute ignored" }
+}
+
+[[assume (true)]] int bar ();			// { dg-error "'assume' attribute ignored" }
+using foobar [[assume (true)]] = int;		// { dg-error "'assume' attribute ignored" }
+[[assume (true)]] int a;			// { dg-error "'assume' attribute ignored" }
+[[assume (true)]] auto [b, c] = arr;		// { dg-error "'assume' attribute ignored" }
+						// { dg-error "structured bindings only available with" "" { target c++14_down } .-1 }
+[[assume (true)]];				// { dg-warning "attribute ignored" }
+inline [[assume (true)]] void baz () {}		// { dg-warning "attribute ignored" }
+						// { dg-error "standard attributes in middle of decl-specifiers" "" { target *-*-* } .-1 }
+constexpr [[assume (true)]] int qux () { return 0; }	// { dg-warning "attribute ignored" }
+						// { dg-error "standard attributes in middle of decl-specifiers" "" { target *-*-* } .-1 }
+int [[assume (true)]] d;			// { dg-warning "attribute ignored" }
+int const [[assume (true)]] e = 1;		// { dg-warning "attribute ignored" }
+struct A {} [[assume (true)]];			// { dg-warning "attribute ignored in declaration of 'struct A'" }
+struct A [[assume (true)]];			// { dg-warning "attribute ignored" }
+struct A [[assume (true)]] a1;			// { dg-warning "attribute ignored" }
+A [[assume (true)]] a2;				// { dg-warning "attribute ignored" }
+enum B { B0 } [[assume (true)]];		// { dg-warning "attribute ignored in declaration of 'enum B'" }
+enum B [[assume (true)]];			// { dg-warning "attribute ignored" }
+enum B [[assume (true)]] b1;			// { dg-warning "attribute ignored" }
+B [[assume (true)]] b2;				// { dg-warning "attribute ignored" }
+struct [[assume (true)]] C {};			// { dg-error "'assume' attribute ignored" }
+int f [[assume (true)]];			// { dg-error "'assume' attribute ignored" }
+int g[2] [[assume (true)]];			// { dg-error "'assume' attribute ignored" }
+int g2 [[assume (true)]] [2];			// { dg-error "'assume' attribute ignored" }
+int corge () [[assume (true)]];			// { dg-error "'assume' attribute ignored" }
+int *[[assume (true)]] h;			// { dg-error "'assume' attribute ignored" }
+int & [[assume (true)]] i = f;			// { dg-error "'assume' attribute ignored" }
+int && [[assume (true)]] j = 0;			// { dg-error "'assume' attribute ignored" }
+int S::* [[assume (true)]] k;			// { dg-error "'assume' attribute ignored" }
+auto l = sizeof (int [2] [[assume (true)]]);	// { dg-error "'assume' attribute ignored" }
+int freddy ([[assume (true)]] int a,		// { dg-error "'assume' attribute ignored" }
+	    [[assume (true)]] int,		// { dg-error "'assume' attribute ignored" }
+	    [[assume (true)]] int c = 0,	// { dg-error "'assume' attribute ignored" }
+	    [[assume (true)]] int = 0);		// { dg-error "'assume' attribute ignored" }
+void
+corge ([[assume (true)]] int a,			// { dg-error "'assume' attribute ignored" }
+       [[assume (true)]] int,			// { dg-error "'assume' attribute ignored" }
+       [[assume (true)]] int c = 0,		// { dg-error "'assume' attribute ignored" }
+       [[assume (true)]] int = 0)		// { dg-error "'assume' attribute ignored" }
+{
+}
+[[assume (true)]] void
+garply ()					// { dg-error "'assume' attribute ignored" }
+{
+}
+int grault (int [[assume (true)]] a,		// { dg-warning "attribute ignored" }
+	    int [[assume (true)]],		// { dg-warning "attribute ignored" }
+	    int [[assume (true)]] c = 0,	// { dg-warning "attribute ignored" }
+	    int [[assume (true)]] = 0);		// { dg-warning "attribute ignored" }
+void
+waldo (int [[assume (true)]] a,			// { dg-warning "attribute ignored" }
+       int [[assume (true)]],			// { dg-warning "attribute ignored" }
+       int [[assume (true)]] c = 0,		// { dg-warning "attribute ignored" }
+       int [[assume (true)]] = 0)		// { dg-warning "attribute ignored" }
+{
+}
+int plugh (int a [[assume (true)]],		// { dg-error "'assume' attribute ignored" }
+	    int b [[assume (true)]] = 0);	// { dg-error "'assume' attribute ignored" }
+void
+thud (int a [[assume (true)]],			// { dg-error "'assume' attribute ignored" }
+      int b [[assume (true)]] = 0)		// { dg-error "'assume' attribute ignored" }
+{
+}
+enum [[assume (true)]] D { D0 };		// { dg-error "'assume' attribute ignored" }
+enum class [[assume (true)]] E { E0 };		// { dg-error "'assume' attribute ignored" }
+enum F {};
+enum [[assume (true)]] F;			// { dg-warning "type attributes ignored after type is already defined" }
+enum G {
+  G0 [[assume (true)]],				// { dg-error "'assume' attribute ignored" }
+  G1 [[assume (true)]] = 2			// { dg-error "'assume' attribute ignored" }
+};
+namespace [[assume (true)]] H { using H0 = int; }	// { dg-warning "'assume' attribute directive ignored" } */
+namespace [[assume (true)]] {}			// { dg-warning "'assume' attribute directive ignored" }
+[[assume (true)]] using namespace H;		// { dg-warning "'assume' attribute directive ignored" }
+struct [[assume (true)]] I			// { dg-error "'assume' attribute ignored" }
+{
+  [[assume (true)]];				// { dg-error "declaration does not declare anything" }
+  [[assume (true)]] int i;			// { dg-error "'assume' attribute ignored" }
+  [[assume (true)]] int foo ();			// { dg-error "'assume' attribute ignored" }
+  [[assume (true)]] int bar () { return 1; }	// { dg-error "'assume' attribute ignored" }
+  [[assume (true)]] int : 0;			// { dg-error "'assume' attribute ignored" }
+  [[assume (true)]] int i2 : 5;			// { dg-error "'assume' attribute ignored" }
+  [[assume (true)]] static int i3;		// { dg-error "'assume' attribute ignored" }
+  static int i4;
+};
+[[assume (true)]] int I::i4 = 0;		// { dg-error "'assume' attribute ignored" }
+struct J : [[assume (true)]] C {};		// { dg-warning "attributes on base specifiers are ignored" }
+#if __cpp_concepts >= 201907L
+template <typename T>
+concept K [[assume (true)]] = requires { true; };	// { dg-error "'assume' attribute ignored" "" { target c++20 } }
+#endif
+typedef int L [[assume (true)]];		// { dg-error "'assume' attribute ignored" }
+template <typename T>
+struct M {};
+template <>
+struct [[assume (true)]] M<int> { int m; };	// { dg-error "'assume' attribute ignored" }
+typedef int N[2] [[assume (true)]];		// { dg-error "'assume' attribute ignored" }
+typedef int O [[assume (true)]] [2];		// { dg-error "'assume' attribute ignored" }