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| author | Marek Polacek <polacek@redhat.com> | 2022-04-01 16:55:58 -0400 |
|---|---|---|
| committer | Marek Polacek <polacek@redhat.com> | 2022-05-18 17:43:56 -0400 |
| commit | 7da9a089608b0ca09683332ce014fb6184842724 (patch) | |
| tree | a66671c0a6edc1a4191f4ec0d97d6a5c55ff6191 /gcc/c-family/c.opt | |
| parent | 1875214cd1ca3e8bd0121f703537eb98edd84027 (diff) | |
| download | gcc-7da9a089608b0ca09683332ce014fb6184842724.zip gcc-7da9a089608b0ca09683332ce014fb6184842724.tar.gz gcc-7da9a089608b0ca09683332ce014fb6184842724.tar.bz2 | |
c: Implement new -Wenum-int-mismatch warning [PR105131]
In C, an enumerated type is compatible with char, a signed integer type,
or an unsigned integer type (6.7.2.2/5). Therefore this code compiles:
enum E { l = -1, z = 0, g = 1 };
int foo(void);
enum E foo(void) { return z; }
if the underlying type of 'enum E' is 'int' (if not, we emit an error).
This is different for typedefs, where C11 permits typedefs to be
redeclared to the same type, but not to compatible types. In C++, the
code above is invalid.
It seems desirable to emit a warning in the C case, because it is
probably a mistake and definitely a portability error, given that the
choice of the underlying type is implementation-defined.
To that end, this patch implements a new -Wenum-int-mismatch warning.
Conveniently, we already have comptypes_check_enum_int to detect such
mismatches. This warning is enabled by either -Wall or -Wc++-compat.
PR c/105131
gcc/c-family/ChangeLog:
* c.opt (Wenum-int-mismatch): New.
gcc/c/ChangeLog:
* c-decl.cc (diagnose_mismatched_decls): Warn about enum/integer type
mismatches.
* c-tree.h (comptypes_check_enum_int): Declare.
* c-typeck.cc (comptypes): No longer static.
gcc/ChangeLog:
* doc/invoke.texi: Document -Wenum-int-mismatch.
gcc/testsuite/ChangeLog:
* gcc.dg/Wenum-int-mismatch-1.c: New test.
* gcc.dg/Wenum-int-mismatch-2.c: New test.
* gcc.dg/Wenum-int-mismatch-3.c: New test.
* gcc.dg/Wenum-int-mismatch-4.c: New test.
* gcc.dg/Wenum-int-mismatch-5.c: New test.
Diffstat (limited to 'gcc/c-family/c.opt')
| -rw-r--r-- | gcc/c-family/c.opt | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt index 035b1de..41a20bc6 100644 --- a/gcc/c-family/c.opt +++ b/gcc/c-family/c.opt @@ -638,6 +638,10 @@ Wenum-conversion C ObjC C++ ObjC++ Var(warn_enum_conversion) Init(0) Warning LangEnabledBy(C ObjC,Wextra) Warn about implicit conversion of enum types. +Wenum-int-mismatch +C ObjC Var(warn_enum_int_mismatch) Warning LangEnabledBy(C ObjC,Wall || Wc++-compat) +Warn about enum/integer type mismatches. + Werror C ObjC C++ ObjC++ ; Documented in common.opt |