c++: fix 'unsigned __int128_t' semantics [PR108099]

My earlier patch for 108099 made us accept this non-standard pattern but
messed up the semantics, so that e.g. unsigned __int128_t was not a 128-bit
type.

	PR c++/108099

gcc/cp/ChangeLog:

	* decl.cc (grokdeclarator): Keep typedef_decl for __int128_t.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/int128-8.C: New test.

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index cbb9f20b7a487bfa34c53624f9b2aedff21350a0..f514377dd424a4f7ee65415529449de773aedd76 100644 (file)
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -12304,12 +12304,14 @@ grokdeclarator (const cp_declarator *declarator,
                       key, typedef_decl);
              ok = !flag_pedantic_errors;
              if (is_typedef_decl (typedef_decl))
-               type = DECL_ORIGINAL_TYPE (typedef_decl);
+               {
+                 type = DECL_ORIGINAL_TYPE (typedef_decl);
+                 typedef_decl = NULL_TREE;
+               }
              else
                /* PR108099: __int128_t comes from c_common_nodes_and_builtins,
                   and is not built as a typedef.  */
                type = TREE_TYPE (typedef_decl);
-             typedef_decl = NULL_TREE;
            }
          else if (declspecs->decltype_p)
            error_at (loc, "%qs specified with %<decltype%>", key);

diff --git a/gcc/testsuite/g++.dg/ext/int128-8.C b/gcc/testsuite/g++.dg/ext/int128-8.C
new file mode 100644 (file)
index 0000000..14bbc49
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/int128-8.C
@@ -0,0 +1,24 @@
+// PR c++/108099
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+using u128 = unsigned __int128_t;
+using s128 = signed __int128_t;
+template <typename T, T v> struct integral_constant {
+  static constexpr T value = v;
+};
+typedef integral_constant <bool, false> false_type;
+typedef integral_constant <bool, true> true_type;
+template <class T, class U>
+struct is_same : false_type {};
+template <class T>
+struct is_same <T, T> : true_type {};
+static_assert (is_same <__int128, s128>::value, "");
+static_assert (is_same <signed __int128, s128>::value, "");
+static_assert (is_same <__int128_t, s128>::value, "");
+static_assert (is_same <unsigned __int128, u128>::value, ""); // { dg-bogus "" "" { xfail *-*-* } }
+static_assert (is_same <__uint128_t, u128>::value, "");              // { dg-bogus "" "" { xfail *-*-* } }
+static_assert (sizeof (s128) == sizeof (__int128), "");
+static_assert (sizeof (u128) == sizeof (unsigned __int128), "");
+static_assert (s128(-1) < 0, "");
+static_assert (u128(-1) > 0, "");