[Bug c/109530] New: Warning "is used uninitialized" raised for an initialized variable.

[patrick.pelissier at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109530

Bug ID: 109530
   Summary: Warning "is used uninitialized" raised for an
initialized variable.
   Product: gcc
   Version: 12.2.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c
  Assignee: unassigned at gcc dot gnu.org
  Reporter: patrick.pelissier at gmail dot com
  Target Milestone: ---

For the following program:

#include 
#include 

jmp_buf buf;
jmp_buf buf1;

typedef struct ry_s {
  struct ry_s *next;
} ry_t[1];

struct ry_s *m_global;

static inline void
ry_init(ry_t state)
{
  m_global = state;
}

static inline void
ry_clear(ry_t state)
{
  m_global = state->next;
}

int func2(void)
{
  for(_Bool b = 1 ; b ; b = 0)
for(ry_t test1 ; b ; ry_clear(test1), b = 0 )
  if (ry_init(test1), setjmp (buf) == 0)
{
  FILE *f = fopen("tmp","wt");
  if ((setjmp (buf1) == 0) )
{
  fprintf(f, "This is a text\n");
  fclose(f);
}
}
  return 0;
}


When running with "-O2  -Wall -Wextra", I get the following warning:

: In function 'func2':
:31:17: warning: 'f' is used uninitialized [-Wuninitialized]
   31 |   FILE *f = fopen("tmp","wt");

whereas f is obviously initialized in the statement.
I am confused by this warning.

[Bug c/108201] New: Warning about conversion from unsigned int to unsigned int

[patrick.pelissier at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108201

Bug ID: 108201
   Summary: Warning about conversion from unsigned int to unsigned
int
   Product: gcc
   Version: 12.2.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c
  Assignee: unassigned at gcc dot gnu.org
  Reporter: patrick.pelissier at gmail dot com
  Target Milestone: ---

On a Linux x86_64 system, with GCC 12.2.0, when I build the following program
with -Wsign-conversion , 


  typedef unsigned int m_string_unicode_t;

  void decode(char c, m_string_unicode_t *unicode) {
*unicode = ((*unicode << 6)) | ((m_string_unicode_t) c);
  }

  void decode2(char c, unsigned int *unicode) {
*unicode = ((*unicode << 6)) | ((unsigned int) c);
  }


I get the following wanning:


tst.c: In function 'decode':
tst.c:6:32: warning: conversion to 'm_string_unicode_t' {aka 'unsigned int'}
from 'unsigned int' may change the sign of the result [-Wsign-conversion]


There is a warning for the function decode, but not for the function decode2.

I don't understand the warning as there is no conversion from unsigned int to
unsigned int as both are the same type. I was expecting no warning for both
functions.

The warning only appears with GCC 12 (no issue with GCC 11).

[Bug c/53769] [C11]: Macros __STDC_NO_THREADS__ / __STDC_NO_ATOMIC__ missing.

[patrick.pelissier at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53769

Patrick Pelissier  changed:

   What|Removed |Added

 Status|UNCONFIRMED |RESOLVED
 Resolution|--- |FIXED

--- Comment #12 from Patrick Pelissier  ---
stdc-predef.h fixes the issue.