r14-5059-gd880e093d92084 "c: Add Walloc-size to warn about insufficient size in allocations [PR71219]" looks relevant.

A bit of debugging:

Program received signal SIGSEGV, Segmentation fault.
0x00000000007bfff6 in convert_for_assignment (location=location@entry=263654, expr_loc=expr_loc@entry=0, type=type@entry=0x7fffea029000, rhs=0x7fffea000508,
    origtype=origtype@entry=0x0, errtype=errtype@entry=ic_init, null_pointer_constant=false, fundecl=0x0, function=0x0, parmnum=0, warnopt=0)
    at /home/slyfox/dev/git/gcc/gcc/c/c-typeck.cc:7370
warning: Source file is more recent than executable.
7370                      && INTEGER_CST == TREE_CODE (TYPE_SIZE_UNIT (ttl))
(gdb) bt
#0  0x00000000007bfff6 in convert_for_assignment (location=location@entry=263654, expr_loc=expr_loc@entry=0, type=type@entry=0x7fffea029000, rhs=0x7fffea000508,
    origtype=origtype@entry=0x0, errtype=errtype@entry=ic_init, null_pointer_constant=false, fundecl=0x0, function=0x0, parmnum=0, warnopt=0)
    at /home/slyfox/dev/git/gcc/gcc/c/c-typeck.cc:7370

(gdb) call debug_tree(ttl)
 <void_type 0x7fffea021f18 void VOID
    align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type 0x7fffea021f18
    pointer_to_this <pointer_type 0x7fffea029000>>

Thanks for reporting. I will fix this.

Created attachment 56489 [details]
patch

This should fix it. I am running some tests and will commit this.

Created attachment 56490 [details]
patch

Correct attachment.

Created attachment 56491 [details]
patch

Ok, let's try again...

Another test case:

parse_args(char (**child_args_ptr_ptr)[]) {
  *child_args_ptr_ptr = calloc(1, sizeof(char));
}

when compiled with -Wextra:

$ ~/gcc/results/bin/gcc -c -Wextra bug975.c
bug975.c:1:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
    1 | parse_args(char (**child_args_ptr_ptr)[]) {
      | ^~~~~~~~~~
bug975.c: In function ‘parse_args’:
bug975.c:2:25: warning: implicit declaration of function ‘calloc’ [-Wimplicit-function-declaration]
    2 |   *child_args_ptr_ptr = calloc(1, sizeof(char));
      |                         ^~~~~~
bug975.c:1:1: note: include ‘<stdlib.h>’ or provide a declaration of ‘calloc’
  +++ |+#include <stdlib.h>
    1 | parse_args(char (**child_args_ptr_ptr)[]) {
bug975.c:2:25: warning: incompatible implicit declaration of built-in function ‘calloc’ [-Wbuiltin-declaration-mismatch]
    2 |   *child_args_ptr_ptr = calloc(1, sizeof(char));
      |                         ^~~~~~
bug975.c:2:25: note: include ‘<stdlib.h>’ or provide a declaration of ‘calloc’
bug975.c:2:3: internal compiler error: Segmentation fault
    2 |   *child_args_ptr_ptr = calloc(1, sizeof(char));
      |   ^
0xebd319 crash_signal(int)
	../../trunk.year/gcc/toplev.cc:315
0x74ffd9 convert_for_assignment(unsigned int, unsigned int, tree_node*, tree_node*, tree_node*, impl_conv, bool, tree_node*, tree_node*, int, int)
	../../trunk.year/gcc/c/c-typeck.cc:7370

(In reply to Martin Uecker from comment #6)
> Created attachment 56491 [details]
> patch
> 
> Ok, let's try again...

The change fixes jemalloc and boehm-gc builds for me. Thank you!

The master branch has been updated by Martin Uecker <uecker@gcc.gnu.org>:

https://gcc.gnu.org/g:f432a594fe6d3a0de1330ba69200d158e6248083

commit r14-5084-gf432a594fe6d3a0de1330ba69200d158e6248083
Author: Martin Uecker <uecker@tugraz.at>
Date:   Thu Nov 2 13:12:15 2023 +0100

    c: Add missing conditions in Walloc-size to avoid ICEs [PR112347]
    
    Fix ICE because of forgotten checks for pointers to void
    and incomplete arrays.
    
    Committed as obvious.
    
            PR c/112347
    
    gcc/c:
            * c-typeck.cc (convert_for_assignment): Add missing check.
    
    gcc/testsuite:
    
            * gcc.dg/Walloc-size-3.c: New test.

When this patch was tested, did that include a build of libgfortran ?

I am getting some strange new warnings:

../../../trunk.year/libgfortran/io/async.c:265:24: warning: allocation of insufficient size ‘1’ for type ‘transfer_queue’ with size ‘80’ [-Walloc-size]
../../../trunk.year/libgfortran/io/async.c:287:24: warning: allocation of insufficient size ‘1’ for type ‘transfer_queue’ with size ‘80’ [-Walloc-size]
../../../trunk.year/libgfortran/io/async.c:311:24: warning: allocation of insufficient size ‘1’ for type ‘transfer_queue’ with size ‘80’ [-Walloc-size]
../../../trunk.year/libgfortran/io/async.c:331:24: warning: allocation of insufficient size ‘1’ for type ‘transfer_queue’ with size ‘80’ [-Walloc-size]

The code looks legal to me. Here is the first one:

  transfer_queue *tq = calloc (sizeof (transfer_queue), 1);

In this case this is by design because the size of an element should be second argument to calloc. ("The calloc function allocates space for an array of nmemb objects, each of whose size is size.")

I filed a bug for libfortran: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112364

I have been trying to get this C++ code to produce the new warning:

#include <cstdlib>

struct S
{
	int a[ 10];
	float * b[ 20];
};

extern void g( S * ps);

void f( int n)
{
	S * ps = (S *) calloc( sizeof( S), 1);
	g( ps);

	S * ps2 = (S *) calloc( 1, sizeof( S));
	g( ps2);

	S * ps3 = (S *) calloc( 1, sizeof( S) / 2);
	g( ps3);
}

$ ~/gcc/results/bin/g++ -g -O2 -Wall -Wextra -Walloc-size -c nov2b.cc
cc1plus: warning: command-line option ‘-Walloc-size’ is valid for C/ObjC but not for C++
nov2b.cc: In function ‘void f(int)’:
nov2b.cc:12:13: warning: unused parameter ‘n’ [-Wunused-parameter]
   12 | void f( int n)
      |         ~~~~^
$ ~/gcc/results/bin/g++ -v
Using built-in specs.
COLLECT_GCC=/home/dcb38/gcc/results/bin/g++
COLLECT_LTO_WRAPPER=/home/dcb38/gcc/results.20231102.asan.ubsan/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../trunk.year/configure --prefix=/home/dcb38/gcc/results.20231102.asan.ubsan --disable-multilib --disable-bootstrap --with-build-config=bootstrap-asan --with-build-config=bootstrap-ubsan --with-pkgversion=01c18f58d37865d5 --enable-checking=df,extra,fold,rtl,yes --enable-languages=c,c++,fortran
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.0.0 20231102 (experimental) (01c18f58d37865d5) 
$ 

I think calloc is available in C++, so the warning is wrong.

"I think calloc is available in C++, so the warning is wrong."

I am happy to revise the warning if it is wrong or annoying, but I do not understand what C++ has to do with this.

(In reply to Martin Uecker from comment #14)
> I am happy to revise the warning if it is wrong or annoying, but I do not
> understand what C++ has to do with this.

In file gcc/c-family/c.opt, is the new text

Walloc-size
C ObjC Var(warn_alloc_size) Warning LangEnabledBy(C ObjC, Wextra)
Warn when allocating insufficient storage for the target type of the assigned pointer.

IMHO, it should say:

Walloc-size
C ObjC Var(warn_alloc_size) Warning LangEnabledBy(C ObjC C++, Wextra)
Warn when allocating insufficient storage for the target type of the assigned pointer.

I agree that the C++ should have this warning as well, although it seems less important there. This would be an enhancement request for the C++ FE.

I think this bug is done, anyway?

I think this can be closed.

Thanks! Martin, IIRC you have commit access. If you change your email on BZ to <whatever your sourceware login name is>@gcc.gnu.org, you will get editbugs permissions on Bugzilla.

Ah, this is how it works. Thanks!

(In reply to Martin Uecker from comment #16)
> I agree that the C++ should have this warning as well, although it seems
> less important there. This would be an enhancement request for the C++ FE.

See 112377.