[Bug c/81524] Bogus or missing warnings when dereferencing pointer to deallocated stack memory

["msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81524

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |msebor at gcc dot gnu.org
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |12.0
         Resolution|---                         |FIXED
             Blocks|                            |104077

--- Comment #6 from Martin Sebor <msebor at gcc dot gnu.org> ---
As far as I can see this works as requested without sanitization in GCC 12:

$ (set -x; for p in PARAM RETURN BLOCK; do for m in READ WRITE; do gcc
-DTEST_${p}_$m -S -Wall pr81524.c; done; done)
+ for p in PARAM RETURN BLOCK
+ for m in READ WRITE
+ gcc -DTEST_PARAM_READ -S -Wall pr81524.c
pr81524.c: In function ‘test_param_local’:
pr81524.c:33:7: warning: storing the address of local variable ‘local’ in ‘*pp’
[-Wdangling-pointer=]
   33 |   *pp = &local;
      |   ~~~~^~~~~~~~
pr81524.c:32:7: note: ‘local’ declared here
   32 |   int local = 1;
      |       ^~~~~
pr81524.c:32:7: note: ‘pp’ declared here
+ for m in READ WRITE
+ gcc -DTEST_PARAM_WRITE -S -Wall pr81524.c
pr81524.c: In function ‘test_param_local’:
pr81524.c:33:7: warning: storing the address of local variable ‘local’ in ‘*pp’
[-Wdangling-pointer=]
   33 |   *pp = &local;
      |   ~~~~^~~~~~~~
pr81524.c:32:7: note: ‘local’ declared here
   32 |   int local = 1;
      |       ^~~~~
pr81524.c:32:7: note: ‘pp’ declared here
+ for p in PARAM RETURN BLOCK
+ for m in READ WRITE
+ gcc -DTEST_RETURN_READ -S -Wall pr81524.c
pr81524.c: In function ‘test_return_local’:
pr81524.c:42:10: warning: function returns address of local variable
[-Wreturn-local-addr]
   42 |   return &local;
      |          ^~~~~~
+ for m in READ WRITE
+ gcc -DTEST_RETURN_WRITE -S -Wall pr81524.c
pr81524.c: In function ‘test_return_local’:
pr81524.c:42:10: warning: function returns address of local variable
[-Wreturn-local-addr]
   42 |   return &local;
      |          ^~~~~~
+ for p in PARAM RETURN BLOCK
+ for m in READ WRITE
+ gcc -DTEST_BLOCK_READ -S -Wall pr81524.c
pr81524.c: In function ‘main’:
pr81524.c:88:10: warning: using dangling pointer ‘p’ to ‘local’
[-Wdangling-pointer=]
   88 |   return *p;
      |          ^~
pr81524.c:76:9: note: ‘local’ declared here
   76 |     int local = 1;
      |         ^~~~~
pr81524.c:81:3: warning: using dangling pointer ‘p’ to ‘local’
[-Wdangling-pointer=]
   81 |   printf("%d\n", *p);
      |   ^~~~~~~~~~~~~~~~~~
pr81524.c:76:9: note: ‘local’ declared here
   76 |     int local = 1;
      |         ^~~~~
+ for m in READ WRITE
+ gcc -DTEST_BLOCK_WRITE -S -Wall pr81524.c
pr81524.c: In function ‘main’:
pr81524.c:88:10: warning: using dangling pointer ‘p’ to ‘local’
[-Wdangling-pointer=]
   88 |   return *p;
      |          ^~
pr81524.c:76:9: note: ‘local’ declared here
   76 |     int local = 1;
      |         ^~~~~
pr81524.c:84:6: warning: using dangling pointer ‘p’ to ‘local’
[-Wdangling-pointer=]
   84 |   *p = 1;
      |   ~~~^~~
pr81524.c:76:9: note: ‘local’ declared here
   76 |     int local = 1;
      |         ^~~~~


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104077
[Bug 104077] bogus/missing -Wdangling-pointer