[Bug tree-optimization/115694] [13/14/15 regression] ICE when building scipy with LTO

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115694

--- Comment #7 from Sam James <sjames at gcc dot gnu.org> ---
Standalone, no LTO:
```
_Complex a;
void c();
void d() { c(a); }
typedef struct {
  double a[2];
} b;
void e();
void c(b f) { e(f); }
```

```
$ gcc -c special_wrappers.c.i -O1
during GIMPLE pass: forwprop
special_wrappers.c.i: In function ‘d’:
special_wrappers.c.i:3:6: internal compiler error: Segmentation fault
    3 | void d() { c(a); }
      |      ^
0x561a5c2f5f8a internal_error(char const*, ...)
       
/usr/src/debug/sys-devel/gcc-15.0.9999/gcc-15.0.9999/gcc/diagnostic-global-context.cc:491
0x561a5bba13eb crash_signal
        /usr/src/debug/sys-devel/gcc-15.0.9999/gcc-15.0.9999/gcc/toplev.cc:319
0x561a5c516a65 tree_class_check(tree_node*, tree_code_class, char const*, int,
char const*)
        /usr/src/debug/sys-devel/gcc-15.0.9999/gcc-15.0.9999/gcc/tree.h:3786
0x561a5c516a65 useless_type_conversion_p(tree_node*, tree_node*)
       
/usr/src/debug/sys-devel/gcc-15.0.9999/gcc-15.0.9999/gcc/gimple-expr.cc:86
0x561a5c55d4a0 verify_gimple_assign_single
       
/usr/src/debug/sys-devel/gcc-15.0.9999/gcc-15.0.9999/gcc/tree-cfg.cc:4610
0x561a5c61bf6c verify_gimple_in_cfg(function*, bool, bool)
       
/usr/src/debug/sys-devel/gcc-15.0.9999/gcc-15.0.9999/gcc/tree-cfg.cc:5614
0x561a5c4a5e9c execute_function_todo
        /usr/src/debug/sys-devel/gcc-15.0.9999/gcc-15.0.9999/gcc/passes.cc:2089
0x561a5c4a5e9c do_per_function
        /usr/src/debug/sys-devel/gcc-15.0.9999/gcc-15.0.9999/gcc/passes.cc:1688
0x561a5c4a5e9c execute_todo
        /usr/src/debug/sys-devel/gcc-15.0.9999/gcc-15.0.9999/gcc/passes.cc:2143
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://bugs.gentoo.org/> for instructions.
sam-build /tmp/ice #
```