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| author | Marek Polacek <polacek@redhat.com> | 2015-07-27 12:40:45 +0000 |
|---|---|---|
| committer | Marek Polacek <mpolacek@gcc.gnu.org> | 2015-07-27 12:40:45 +0000 |
| commit | 05b28fd6f91016151e758c2414d7245a54512c99 (patch) | |
| tree | a50a804e0d3bacf0015564dabec36d9c9121f14d /gcc/doc | |
| parent | 0fd357f27d55de9d05662ebce1f166974891f52e (diff) | |
| download | gcc-05b28fd6f91016151e758c2414d7245a54512c99.zip gcc-05b28fd6f91016151e758c2414d7245a54512c99.tar.gz gcc-05b28fd6f91016151e758c2414d7245a54512c99.tar.bz2 | |
re PR c++/66555 (Fails to warn for if (j == 0 && i == i))
PR c++/66555
PR c/54979
* c-common.c (find_array_ref_with_const_idx_r): New function.
(warn_tautological_cmp): New function.
* c-common.h (warn_tautological_cmp): Declare.
* c.opt (Wtautological-compare): New option.
* c-typeck.c (parser_build_binary_op): Call warn_tautological_cmp.
* call.c (build_new_op_1): Call warn_tautological_cmp.
* pt.c (tsubst_copy_and_build): Use sentinel to suppress tautological
compare warnings.
* doc/invoke.texi: Document -Wtautological-compare.
* c-c++-common/Wtautological-compare-1.c: New test.
From-SVN: r226242
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/invoke.texi | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 54e7a67..e988444 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -283,7 +283,8 @@ Objective-C and Objective-C++ Dialects}. -Wsuggest-final-types @gol -Wsuggest-final-methods -Wsuggest-override @gol -Wmissing-format-attribute @gol -Wswitch -Wswitch-default -Wswitch-enum -Wswitch-bool -Wsync-nand @gol --Wsystem-headers -Wtrampolines -Wtrigraphs -Wtype-limits -Wundef @gol +-Wsystem-headers -Wtautological-compare -Wtrampolines -Wtrigraphs @gol +-Wtype-limits -Wundef @gol -Wuninitialized -Wunknown-pragmas -Wno-pragmas @gol -Wunsuffixed-float-constants -Wunused -Wunused-function @gol -Wunused-label -Wunused-local-typedefs -Wunused-parameter @gol @@ -3452,6 +3453,7 @@ Options} and @ref{Objective-C and Objective-C++ Dialect Options}. -Wenum-compare @r{(in C/ObjC; this is on by default in C++)} @gol -Wimplicit-int @r{(C and Objective-C only)} @gol -Wimplicit-function-declaration @r{(C and Objective-C only)} @gol +-Wbool-compare @gol -Wcomment @gol -Wformat @gol -Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)} @gol @@ -3468,6 +3470,7 @@ Options} and @ref{Objective-C and Objective-C++ Dialect Options}. -Wstrict-aliasing @gol -Wstrict-overflow=1 @gol -Wswitch @gol +-Wtautological-compare @gol -Wtrigraphs @gol -Wuninitialized @gol -Wunknown-pragmas @gol @@ -4513,6 +4516,18 @@ code. However, note that using @option{-Wall} in conjunction with this option does @emph{not} warn about unknown pragmas in system headers---for that, @option{-Wunknown-pragmas} must also be used. +@item -Wtautological-compare +@opindex Wtautological-compare +@opindex Wno-tautological-compare +Warn if a self-comparison always evaluates to true or false. This +warning detects various mistakes such as: +@smallexample +int i = 1; +@dots{} +if (i > i) @{ @dots{} @} +@end smallexample +This warning is enabled by @option{-Wall}. + @item -Wtrampolines @opindex Wtrampolines @opindex Wno-trampolines |