This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [patch] fix c++/27975, add new warning option -Wenum-compare
Hi,
On Thu, 22 May 2008, Richard Guenther wrote:
> >> Right now it's disabled by default, but we could enable it with -Wall or
> >> -Wextra, I'll do whatever is decided.
> >
> > It seems to me that this option was previously always emitted. So I
> > think that -Wenum-compare should be turned on by -Wall.
>
> IMHO it should be on by default as an implicit conversion of one enum
> type to another is an error in C++.
I've checked in the below as r136035. It adds two testcases (there were
none for this warning), and activates the warning by default without any
options, as before. (all regstrapped on i686 and x86-64)
Ciao,
Michael.
--
Fix c++/27975.
* c.opt (Wenum-compare): New warning option.
* doc/invoke.texi (Warning Options): Document -Wenum-compare.
cp/
* call.c (build_new_op): Make warning conditional on OPT_Wenum_compare.
testsuite/
* g++.dg/warn/Wenum-compare.C: New testcase.
* g++.dg/warn/Wenum-compare-no.C: Ditto.
Index: c.opt
===================================================================
*** c.opt (revision 136032)
--- c.opt (working copy)
*************** Wendif-labels
*** 195,200 ****
--- 195,204 ----
C ObjC C++ ObjC++ Warning
Warn about stray tokens after #elif and #endif
+ Wenum-compare
+ C++ ObjC++ Var(warn_enum_compare) Init(1) Warning
+ Warn about comparison of different enum types
+
Werror
C ObjC C++ ObjC++
; Documented in common.opt
Index: cp/call.c
===================================================================
*** cp/call.c (revision 136034)
--- cp/call.c (working copy)
*************** build_new_op (enum tree_code code, int f
*** 4004,4010 ****
!= TYPE_MAIN_VARIANT (TREE_TYPE (arg2)))
&& (complain & tf_warning))
{
! warning (0, "comparison between %q#T and %q#T",
TREE_TYPE (arg1), TREE_TYPE (arg2));
}
break;
--- 4004,4011 ----
!= TYPE_MAIN_VARIANT (TREE_TYPE (arg2)))
&& (complain & tf_warning))
{
! warning (OPT_Wenum_compare,
! "comparison between %q#T and %q#T",
TREE_TYPE (arg1), TREE_TYPE (arg2));
}
break;
Index: doc/invoke.texi
===================================================================
*** doc/invoke.texi (revision 135970)
--- doc/invoke.texi (working copy)
*************** Objective-C and Objective-C++ Dialects}.
*** 232,238 ****
-Wchar-subscripts -Wclobbered -Wcomment @gol
-Wconversion -Wcoverage-mismatch -Wno-deprecated @gol
-Wno-deprecated-declarations -Wdisabled-optimization -Wno-div-by-zero @gol
! -Wempty-body -Wno-endif-labels @gol
-Werror -Werror=* @gol
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-contains-nul -Wno-format-extra-args -Wformat-nonliteral @gol
--- 232,238 ----
-Wchar-subscripts -Wclobbered -Wcomment @gol
-Wconversion -Wcoverage-mismatch -Wno-deprecated @gol
-Wno-deprecated-declarations -Wdisabled-optimization -Wno-div-by-zero @gol
! -Wempty-body -Wenum-compare -Wno-endif-labels @gol
-Werror -Werror=* @gol
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-contains-nul -Wno-format-extra-args -Wformat-nonliteral @gol
*************** while} statement. Additionally, in C++,
*** 3658,3663 ****
--- 3659,3669 ----
in a @samp{while} or @samp{for} statement with no whitespacing before
the semicolon. This warning is also enabled by @option{-Wextra}.
+ @item -Wenum-compare @r{(C++ and Objective-C++ only)}
+ @opindex Wenum-compare
+ @opindex Wno-enum-compare
+ Warn about a comparison between values of different enum types.
+
@item -Wsign-compare
@opindex Wsign-compare
@opindex Wno-sign-compare
Index: testsuite/g++.dg/warn/Wenum-compare-no.C
===================================================================
*** testsuite/g++.dg/warn/Wenum-compare-no.C (revision 0)
--- testsuite/g++.dg/warn/Wenum-compare-no.C (revision 0)
***************
*** 0 ****
--- 1,10 ----
+ /* Test disabling -Wenum-compare (on by default). See PR27975. */
+ /* { dg-do compile } */
+ /* { dg-options "-Wno-enum-compare" } */
+ enum E1 { a };
+ enum E2 { b };
+
+ int foo (E1 e1, E2 e2)
+ {
+ return e1 == e2; /* { dg-bogus "comparison between" } */
+ }
Index: testsuite/g++.dg/warn/Wenum-compare.C
===================================================================
*** testsuite/g++.dg/warn/Wenum-compare.C (revision 0)
--- testsuite/g++.dg/warn/Wenum-compare.C (revision 0)
***************
*** 0 ****
--- 1,10 ----
+ /* Test that we get the -Wenum-compare by default. See PR27975. */
+ /* { dg-do compile } */
+ /* { dg-options "" } */
+ enum E1 { a };
+ enum E2 { b };
+
+ int foo (E1 e1, E2 e2)
+ {
+ return e1 == e2; /* { dg-warning "comparison between" } */
+ }