RE: Compiler warnings while compiling gcc with clang‏

[Aditya K <hiraditya at msn dot com>]

----------------------------------------
> CC: jwakely.gcc@gmail.com; renato.golin@linaro.org; gcc@gcc.gnu.org
> From: pinskia@gmail.com
> Subject: Re: Compiler warnings while compiling gcc with clang‏
> Date: Tue, 5 May 2015 20:19:04 -0700
> To: hiraditya@msn.com
>
>
>
>
>
>> On May 5, 2015, at 8:13 PM, Aditya K <hiraditya@msn.com> wrote:
>>
>> So, I analyzed other warnings and following is the list of relevant warning that I could collect. Hope this is useful.
>>
>>
>> gcc/ipa-icf.c:508:12: warning: logical not is only applied to the left hand side of this comparison
>> ../../gcc/ipa-icf.c:508:12: warning: logical not is only applied to the left hand side of this comparison [-Wlogical-not-parentheses]
>> if ((!type == FUNC || address || !opt_for_fn (decl, optimize_size))
>>
>> gcc/expr.c:5271:9: warning: comparison of constant -1 with expression of type 'unsigned int' is always false [-Wtautological-constant-out-of-range-compare]
>> ../../gcc/expr.c:5271:9: warning: comparison of constant -1 with expression of type 'unsigned int' is always false [-Wtautological-constant-out-of-range-compare]
>> if (!SUBREG_CHECK_PROMOTED_SIGN (target,
>> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> There was a similar bug posted some time ago (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61271)
>> --------------------------------------------------------------------------------------------------------------------------------
>>
>> gcc/reload1.c:470:28: warning: incrementing expression of type bool is deprecated [-Wdeprecated-increment-bool]
>> ../../gcc/reload1.c:470:28: warning: incrementing expression of type bool is deprecated [-Wdeprecated-increment-bool]
>> spill_indirect_levels++;
>> ~~~~~~~~~~~~~~~~~~~~~^
>>
>> Seems like for this bug we need to change the declaration of
>>
>> bool this_target_reload::x_spill_indirect_levels to an int. Even the comment there mentions that this variable might take
>> other integral values.
>>
>> /* Nonzero if indirect addressing is supported on the machine; this means
>> that spilling (REG n) does not require reloading it into a register in
>> order to do (MEM (REG n)) or (MEM (PLUS (REG n) (CONST_INT c))). The
>> value indicates the level of indirect addressing supported, e.g., two
>> means that (MEM (MEM (REG n))) is also valid if (REG n) does not get
>> a hard register. */
>> bool x_spill_indirect_levels;
>>
>>
>> --------------------------------------------------------------------------------------------------------------------------------
>>
>> gcc/rtlanal.c:5573:23: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
>> ../../gcc/rtlanal.c:5573:23: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
>> *second = GEN_INT (CONST_DOUBLE_HIGH (value));
>> ^~~~~~~~~~~~~~~~~~~~~~~~~
>
> These warnings are bogus due to the array being the last element of the structure.
>
> Please file that with clang.
>

IIRC, C++ does not allow flexible array members.

Thanks,
-Aditya


> Thanks,
> Andrew
>
>
>
>>
>> ../../gcc/rtl.h:1757:30: note: expanded from macro 'CONST_DOUBLE_HIGH'
>> #define CONST_DOUBLE_HIGH(r) XCMWINT (r, 1, CONST_DOUBLE, VOIDmode)
>> ^ ~
>> ../../gcc/rtl.h:1123:36: note: expanded from macro 'XCMWINT'
>> #define XCMWINT(RTX, N, C, M) ((RTX)->u.hwint[N])
>> ^
>> ../../gcc/rtl.h:3193:51: note: expanded from macro 'GEN_INT'
>> #define GEN_INT(N) gen_rtx_CONST_INT (VOIDmode, (N))
>> ^
>> ../../gcc/rtl.h:397:5: note: array 'hwint' declared here
>> HOST_WIDE_INT hwint[1];
>> ^
>> ../../gcc/hwint.h:54:26: note: expanded from macro 'HOST_WIDE_INT'
>> # define HOST_WIDE_INT long
>> ^
>>
>> --------------------------------------------------------------------------------------------------------------------------------
>>
>> gcc/vec.h:1048:10: warning: offset of on non-POD type 'vec_embedded' (aka 'vec<c_expr::id_tab, va_heap, vl_embed>') [-Winvalid-offsetof]
>> ../../gcc/vec.h:1048:10: warning: offset of on non-POD type 'vec_embedded' (aka 'vec<std::pair<expr_hash_elt *, expr_hash_elt *>, va_heap, vl_embed>') [-Winvalid-offsetof]
>> return offsetof (vec_embedded, m_vecdata) + alloc * sizeof (T);
>> ^ ~~~~~~~~~
>> /home/hiraditya/work/llvm/install-release/bin/../lib/clang/3.7.0/include/stddef.h:120:24: note: expanded from macro 'offsetof'
>> #define offsetof(t, d) __builtin_offsetof(t, d)
>>
>>
>> --------------------------------------------------------------------------------------------------------------------------------
>>
>> genrtl.h:435:3: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
>> ./genrtl.h:435:3: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
>> XWINT (rt, 1) = arg1;
>> ^ ~
>> ../../gcc/rtl.h:1120:29: note: expanded from macro 'XWINT'
>> #define XWINT(RTX, N) ((RTX)->u.hwint[N])
>> ^
>> ../../gcc/rtl.h:397:5: note: array 'hwint' declared here
>> HOST_WIDE_INT hwint[1];
>> ^
>> ../../gcc/hwint.h:54:26: note: expanded from macro 'HOST_WIDE_INT'
>> # define HOST_WIDE_INT long
>>
>> --------------------------------------------------------------------------------------------------------------------------------
>>
>> gcc/final.c:3957:8: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
>> ../../gcc/final.c:3957:8: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
>> if (CONST_DOUBLE_HIGH (x))
>> ^~~~~~~~~~~~~~~~~~~~~
>> ../../gcc/rtl.h:1757:30: note: expanded from macro 'CONST_DOUBLE_HIGH'
>> #define CONST_DOUBLE_HIGH(r) XCMWINT (r, 1, CONST_DOUBLE, VOIDmode)
>> ^ ~
>> ../../gcc/rtl.h:1123:36: note: expanded from macro 'XCMWINT'
>> #define XCMWINT(RTX, N, C, M) ((RTX)->u.hwint[N])
>> ^
>> ../../gcc/rtl.h:397:5: note: array 'hwint' declared here
>> HOST_WIDE_INT hwint[1];
>> ^
>> ../../gcc/hwint.h:54:26: note: expanded from macro 'HOST_WIDE_INT'
>> # define HOST_WIDE_INT long
>> ^
>>
>> --------------------------------------------------------------------------------------------------------------------------------
>>
>> gcc/cse.c:6171:38: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
>> ../../gcc/cse.c:6171:38: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
>> || (CONST_DOUBLE_P (new_rtx) && CONST_DOUBLE_HIGH (new_rtx)>= 0))
>> ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>> ../../gcc/rtl.h:1757:30: note: expanded from macro 'CONST_DOUBLE_HIGH'
>> #define CONST_DOUBLE_HIGH(r) XCMWINT (r, 1, CONST_DOUBLE, VOIDmode)
>> ^ ~
>> ../../gcc/rtl.h:1123:36: note: expanded from macro 'XCMWINT'
>> #define XCMWINT(RTX, N, C, M) ((RTX)->u.hwint[N])
>> ^
>> ../../gcc/rtl.h:397:5: note: array 'hwint' declared here
>> HOST_WIDE_INT hwint[1];
>> ^
>> ../../gcc/hwint.h:54:26: note: expanded from macro 'HOST_WIDE_INT'
>> # define HOST_WIDE_INT long
>> ^
>>
>> --------------------------------------------------------------------------------------------------------------------------------
>>
>> gcc/gcov-tool.c:225:7: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
>> gcc/gcov-tool.c:493:7: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
>> ../../gcc/gcov-tool.c:225:7: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
>> if (argc - optind == 2)
>> ^~~~~~~~~~~~~~~~~~
>> ../../gcc/gcov-tool.c:230:10: note: uninitialized use occurs here
>> return ret;
>> ^~~
>> ../../gcc/gcov-tool.c:225:3: note: remove the 'if' if its condition is always true
>> if (argc - optind == 2)
>> ^~~~~~~~~~~~~~~~~~~~~~~
>> ../../gcc/gcov-tool.c:196:10: note: initialize the variable 'ret' to silence this warning
>> int ret;
>> ^
>> = 0
>> ../../gcc/gcov-tool.c:493:7: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
>> if (argc - optind == 2)
>> ^~~~~~~~~~~~~~~~~~
>> ../../gcc/gcov-tool.c:498:10: note: uninitialized use occurs here
>> return ret;
>> ^~~
>> ../../gcc/gcov-tool.c:493:3: note: remove the 'if' if its condition is always true
>> if (argc - optind == 2)
>> ^~~~~~~~~~~~~~~~~~~~~~~
>> ../../gcc/gcov-tool.c:462:10: note: initialize the variable 'ret' to silence this warning
>> int ret;
>> ^
>> = 0
>>
>>
>> I think I can fix few of these if we want them to be fixed.
>> For some e.g. ( gcc/gcov-tool.c:225:7: warning: array index 1 is past the end of the array (which contains 1 element) ),
>> I have no idea what is the proper fix for them.
>>
>> -Aditya
>>
>>
>>> Date: Tue, 5 May 2015 21:57:08 +0100
>>> Subject: Re: Compiler warnings while compiling gcc with clang‏
>>> From: jwakely.gcc@gmail.com
>>> To: hiraditya@msn.com
>>> CC: pinskia@gmail.com; renato.golin@linaro.org; gcc@gcc.gnu.org
>>>
>>>> On 5 May 2015 at 12:39, Aditya K wrote:
>>>> There are however, other differences between class and struct (http://stackoverflow.com/a/999810/811335) i.e.,
>>>>
>>>> 1. In absence of an access-specifier for a base class, public is assumed when the derived class is declared struct and private is assumed when the class is declared class.
>>>
>>> Yes, everyone here knows that. That is only relevant to the definition
>>> of the class, which can only occur once. For the purposes of
>>> declarations that are not definitions there is no difference.
>>>
>>>> 2. class can be used in place of a typename to declare a template parameter, while the struct cannot.
>>>
>>> Completely irrelevant in this context. The use of 'class' in a
>>> template parameter list has nothing to do with struct or class types,
>>> nor forward declarations of struct or class types.
>>