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RE: Compiler warnings while compiling gcc with clang‏


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));
                             ^~~~~~~~~~~~~~~~~~~~~~~~~

../../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.
 		 	   		  

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