public inbox for gcc-patches@gcc.gnu.org
 help / color / mirror / Atom feed
* [C PATCH] PR43651: add warning for duplicate qualifier
@ 2016-04-04 10:29 Mikhail Maltsev
  2016-04-07 21:50 ` Joseph Myers
  2016-04-08 17:55 ` Martin Sebor
  0 siblings, 2 replies; 9+ messages in thread
From: Mikhail Maltsev @ 2016-04-04 10:29 UTC (permalink / raw)
  To: gcc-patches, Joseph Myers, Marek Polacek, David Malcolm

[-- Attachment #1: Type: text/plain, Size: 1326 bytes --]

Hi all!

Currently GCC produces pedantic warning, if variable declaration (or
typedef) has duplicate qualifier, but only when compiling as C89 (not
C99 or C11).

The attached patch adds a new warning option to enable the same warning
in C99 and C11. It also checks whether qualifiers come from macro
expansion, e.g.:

#define CT2 const int
const CT2 x1;
CT2 const x2;

and does not warn in this case, but warns for, e.g.

void foo(const int const *x) { }
(because this probably meant to be "const int *const x")

The name for new option "-Wduplicate-decl-specifier" and wording was
chosen to match the same option in Clang.

Bootstrapped and regtested on x86_64-linux. OK for next stage 1?

-- 
Regards,
    Mikhail Maltsev


gcc/c/ChangeLog:

2016-04-04  Mikhail Maltsev  <maltsevm@gmail.com>

        PR c/43651
        * c-decl.c (declspecs_add_qual): Warn when
-Wduplicate-decl-specifier
        is enabled.
        * c-errors.c (pedwarn_c90): Return true if warned.
        * c-tree.h: Change return type to bool.

gcc/testsuite/ChangeLog:

2016-04-04  Mikhail Maltsev  <maltsevm@gmail.com>

        PR c/43651
        * gcc.dg/Wduplicate-decl-specifier.c: New test.


gcc/c-family/ChangeLog:

2016-04-04  Mikhail Maltsev  <maltsevm@gmail.com>

        PR c/43651
        * c.opt (Wduplicate-decl-specifier): New option.

[-- Attachment #2: pr43651.patch --]
[-- Type: text/x-patch, Size: 6012 bytes --]

diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 4f86876..1650b25 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -1000,6 +1000,10 @@ Wsubobject-linkage
 C++ ObjC++ Var(warn_subobject_linkage) Warning Init(1)
 Warn if a class type has a base or a field whose type uses the anonymous namespace or depends on a type with no linkage.
 
+Wduplicate-decl-specifier
+C ObjC Var(warn_duplicate_decl_specifier) Warning LangEnabledBy(C ObjC,Wall)
+Warn when a variable declaration has duplicate const, volatile or restrict specifier.
+
 ansi
 C ObjC C++ ObjC++
 A synonym for -std=c89 (for C) or -std=c++98 (for C++).
diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index 0dd2121..9902326 100644
--- a/gcc/c/c-decl.c
+++ b/gcc/c/c-decl.c
@@ -9539,21 +9539,25 @@ declspecs_add_qual (source_location loc,
   gcc_assert (TREE_CODE (qual) == IDENTIFIER_NODE
 	      && C_IS_RESERVED_WORD (qual));
   i = C_RID_CODE (qual);
+  location_t prev_loc = 0;
   switch (i)
     {
     case RID_CONST:
       dupe = specs->const_p;
       specs->const_p = true;
+      prev_loc = specs->locations[cdw_const];
       specs->locations[cdw_const] = loc;
       break;
     case RID_VOLATILE:
       dupe = specs->volatile_p;
       specs->volatile_p = true;
+      prev_loc = specs->locations[cdw_volatile];
       specs->locations[cdw_volatile] = loc;
       break;
     case RID_RESTRICT:
       dupe = specs->restrict_p;
       specs->restrict_p = true;
+      prev_loc = specs->locations[cdw_restrict];
       specs->locations[cdw_restrict] = loc;
       break;
     case RID_ATOMIC:
@@ -9564,7 +9568,17 @@ declspecs_add_qual (source_location loc,
       gcc_unreachable ();
     }
   if (dupe)
-    pedwarn_c90 (loc, OPT_Wpedantic, "duplicate %qE", qual);
+    {
+      bool warned = pedwarn_c90 (loc, OPT_Wpedantic,
+				 "duplicate %qE declaration specifier", qual);
+      if (!warned
+	  && warn_duplicate_decl_specifier
+	  && prev_loc >= RESERVED_LOCATION_COUNT
+	  && !from_macro_expansion_at (prev_loc)
+	  && !from_macro_expansion_at (loc))
+	warning_at (loc, OPT_Wduplicate_decl_specifier,
+		    "duplicate %qE declaration specifier", qual);
+    }
   return specs;
 }
 
diff --git a/gcc/c/c-errors.c b/gcc/c/c-errors.c
index d5e78b8..af157c0 100644
--- a/gcc/c/c-errors.c
+++ b/gcc/c/c-errors.c
@@ -71,11 +71,12 @@ pedwarn_c99 (location_t location, int opt, const char *gmsgid, ...)
    ISO C99 but not supported in ISO C90, thus we explicitly don't pedwarn
    when C99 is specified.  (There is no flag_c90.)  */
 
-void
+bool
 pedwarn_c90 (location_t location, int opt, const char *gmsgid, ...)
 {
   diagnostic_info diagnostic;
   va_list ap;
+  bool warned = false;
   rich_location richloc (line_table, location);
 
   va_start (ap, gmsgid);
@@ -92,6 +93,7 @@ pedwarn_c90 (location_t location, int opt, const char *gmsgid, ...)
 			       ? DK_PEDWARN : DK_WARNING);
 	  diagnostic.option_index = opt;
 	  report_diagnostic (&diagnostic);
+	  warned = true;
 	  goto out;
 	}
     }
@@ -114,7 +116,9 @@ pedwarn_c90 (location_t location, int opt, const char *gmsgid, ...)
       diagnostic_set_info (&diagnostic, gmsgid, &ap, &richloc, DK_PEDWARN);
       diagnostic.option_index = opt;
       report_diagnostic (&diagnostic);
+      warned = true;
     }
 out:
   va_end (ap);
+  return warned;
 }
diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
index 96ab049..ac72820 100644
--- a/gcc/c/c-tree.h
+++ b/gcc/c/c-tree.h
@@ -716,7 +716,7 @@ extern void c_bind (location_t, tree, bool);
 extern bool tag_exists_p (enum tree_code, tree);
 
 /* In c-errors.c */
-extern void pedwarn_c90 (location_t, int opt, const char *, ...)
+extern bool pedwarn_c90 (location_t, int opt, const char *, ...)
     ATTRIBUTE_GCC_DIAG(3,4);
 extern bool pedwarn_c99 (location_t, int opt, const char *, ...)
     ATTRIBUTE_GCC_DIAG(3,4);
diff --git a/gcc/testsuite/gcc.dg/Wduplicate-decl-specifier.c b/gcc/testsuite/gcc.dg/Wduplicate-decl-specifier.c
new file mode 100644
index 0000000..6b939fb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wduplicate-decl-specifier.c
@@ -0,0 +1,62 @@
+/* PR43651 */
+/* { dg-do compile } */
+/* { dg-options -Wduplicate-decl-specifier } */
+
+typedef const int CT1;
+#define CT2 const int
+typedef volatile int VT1;
+#define VT2 volatile int
+typedef char *restrict RT1;
+#define RT2 char *restrict
+
+void foo(void)
+{
+    const CT1 x1;
+    const CT2 x2;
+    CT1 const x3;
+    CT2 const x4;
+    const int const x5;         /* { dg-warning "duplicate .const." } */
+    const int *const x6;
+    volatile VT1 y1;
+    volatile VT2 y2;
+    VT1 volatile y3;
+    VT2 volatile y4;
+    volatile int volatile y5;   /* { dg-warning "duplicate .volatile." } */
+    volatile int *volatile y6;
+    RT1 restrict r1;
+    RT2 restrict r2;
+    restrict RT1 r3;
+    /* "restrict RT2" is invalid */
+    char *restrict restrict r4; /* { dg-warning "duplicate .restrict." } */
+    char *restrict *restrict r5;
+}
+
+void c1(const CT1 t) { }
+void c2(const CT2 t) { }
+void c3(CT1 const t) { }
+void c4(CT2 const t) { }
+void c5(const int const t) { }  /* { dg-warning "duplicate .const." } */
+void v1(volatile VT1 t) { }
+void v2(volatile VT2 t) { }
+void v3(VT1 volatile t) { }
+void v4(VT2 volatile t) { }
+void v5(volatile int volatile t) { } /* { dg-warning "duplicate .volatile." } */
+void r1(restrict RT1 t) { }
+void r2(RT1 restrict t) { }
+void r3(RT2 restrict t) { }
+void r4(char *restrict restrict t) { }  /* { dg-warning "duplicate .restrict." } */
+
+typedef const CT1 CCT1;
+typedef const CT2 CCT2;
+typedef CT1 const CT1C;
+typedef CT2 const CT2C;
+typedef const int const CIC;    /* { dg-warning "duplicate .const." } */
+typedef volatile VT1 VVT1;
+typedef volatile VT2 VVT2;
+typedef VT1 volatile VT1V;
+typedef VT2 volatile VT2V;
+typedef volatile int volatile VIV; /* { dg-warning "duplicate .volatile." } */
+typedef RT1 restrict RT1R;
+typedef RT2 restrict RT2R;
+typedef restrict RT1 RRT1;
+typedef int *restrict restrict IRR; /* { dg-warning "duplicate .restrict." } */

^ permalink raw reply	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2016-05-11 20:24 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-04-04 10:29 [C PATCH] PR43651: add warning for duplicate qualifier Mikhail Maltsev
2016-04-07 21:50 ` Joseph Myers
2016-04-08 11:42   ` Mikhail Maltsev
2016-04-08 17:55 ` Martin Sebor
2016-04-09 12:29   ` Mikhail Maltsev
2016-04-10 20:12     ` Martin Sebor
2016-04-28 12:00       ` [C PATCH PING] " Mikhail Maltsev
2016-05-10 20:10     ` [C PATCH] " Joseph Myers
2016-05-11 20:24       ` Mikhail Maltsev

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).