From: Jason Merrill <jason@redhat.com>
Date: Tue, 18 Apr 2023 21:12:17 +0000 (-0400)
Subject: c++: fix 'unsigned __int128_t' semantics [PR108099]
X-Git-Tag: basepoints/gcc-15~10051
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ed32ec26697cc77492d094b31a0d2eebc0535644;p=thirdparty%2Fgcc.git

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 772c059dc2c3..ab5cb69b2ae9 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -12482,12 +12482,14 @@ 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
index 000000000000..14bbc49f5c35
--- /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, "");