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C++ PATCH for c++/65327 aka DR 1688 (volatile constexpr variables)

Message ID 20150316133601.GB5698@redhat.com
State New
Headers show

Commit Message

Marek Polacek March 16, 2015, 1:36 p.m. UTC 
The PR points out DR 1688: volatile + constexpr is a valid combination.
This patch makes the compiler accept such a code.

There's a related problem:
constexpr volatile int a = 42;
constexpr int b = a;
the initialization of b should be rejected, but it is not.  My patch does
not address this issue though.

Bootstrapped/regtested on x86_64-linux, ok for trunk?  If so, should this be
backported to 4.8/4.9?

2015-03-16  Marek Polacek  <polacek@redhat.com>

	DR 1688
	PR c++/65327
	* decl.c (grokdeclarator): Allow volatile and constexpr together.

	* g++.dg/cpp0x/constexpr-object1.C: Change dg-error to dg-bogus.
	* g++.dg/cpp0x/pr65327.C: New test.


	Marek

Comments

Jason Merrill March 16, 2015, 6:08 p.m. UTC | #1 
OK for trunk, not for release branches.

Jason
diff mbox

Patch

diff --git gcc/cp/decl.c gcc/cp/decl.c
index e35e484..cb0f11f 100644
--- gcc/cp/decl.c
+++ gcc/cp/decl.c
@@ -10134,8 +10134,9 @@  grokdeclarator (const cp_declarator *declarator,
      the object as `const'.  */
   if (constexpr_p && innermost_code != cdk_function)
     {
-      if (type_quals & TYPE_QUAL_VOLATILE)
-        error ("both %<volatile%> and %<constexpr%> cannot be used here");
+      /* DR1688 says that a `constexpr' specifier in combination with
+	 `volatile' is valid.  */
+
       if (TREE_CODE (type) != REFERENCE_TYPE)
 	{
 	  type_quals |= TYPE_QUAL_CONST;
diff --git gcc/testsuite/g++.dg/cpp0x/constexpr-object1.C gcc/testsuite/g++.dg/cpp0x/constexpr-object1.C
index 41afbe9..287c3ac 100644
--- gcc/testsuite/g++.dg/cpp0x/constexpr-object1.C
+++ gcc/testsuite/g++.dg/cpp0x/constexpr-object1.C
@@ -19,7 +19,7 @@  constexpr A1 a2; // { dg-error "uninitialized const" }
 
 const constexpr A1 a3 = A1();
 
-volatile constexpr A1 a4 = A1(); // { dg-error "both .volatile. and .constexpr. cannot" }
+volatile constexpr A1 a4 = A1(); // { dg-bogus "both .volatile. and .constexpr. cannot" }
 
 // error: on type declaration
 constexpr struct pixel
diff --git gcc/testsuite/g++.dg/cpp0x/pr65327.C gcc/testsuite/g++.dg/cpp0x/pr65327.C
index e69de29..c6cefab 100644
--- gcc/testsuite/g++.dg/cpp0x/pr65327.C
+++ gcc/testsuite/g++.dg/cpp0x/pr65327.C
@@ -0,0 +1,18 @@ 
+// PR c++/65327
+// { dg-do compile { target c++11 } }
+// DR1688 says that constexpr can be used together with volatile.
+
+constexpr volatile int i = 10;
+
+void
+foo ()
+{
+  constexpr volatile int j = 5;
+  static constexpr volatile int k = 5;
+}
+
+constexpr volatile int
+bar ()
+{
+  return i;
+}