[Bug plugins/80094] GCC plugin hash table corruption on hash table expansion (>10 plugins) on GCC 4.5+

["git at lerya dot net" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80094

--- Comment #1 from Vincent Brillault <git at lerya dot net> ---
I've added a patch on the gist
(https://gist.github.com/Feandil/55c104a4e9f5e6c72ce610b152ce37c3#file-gcc-debug-reproducer-patch)
that instrument plugin.c to show the hash map content.

Running the reproducer with a patched gcc should produce something similar to:
```
[...]
Testing known plugins Before insertion
  1(basic_plugin_1): 0x169a6e0 (basic_plugin_1)
  2(basic_plugin_2): 0x169a6e8 (basic_plugin_2)
  3(basic_plugin_3): 0x169a6f0 (basic_plugin_3)
  4(basic_plugin_4): 0x169a6f8 (basic_plugin_4)
  5(basic_plugin_5): 0x169a700 (basic_plugin_5)
  6(basic_plugin_6): 0x169a708 (basic_plugin_6)
  7(basic_plugin_7): 0x169a710 (basic_plugin_7)
  8(basic_plugin_8): 0x169a6b0 (basic_plugin_8)
  9(basic_plugin_9): 0x169a6b8 (basic_plugin_9)
  10(basic_plugin_10): 0x169a6c0 (basic_plugin_10)
  11(basic_plugin_11): (nil)
Inserting basic_plugin_11
Testing known plugins After insertion
  1(basic_plugin_1): (nil)
  2(basic_plugin_2): (nil)
  3(basic_plugin_3): (nil)
  4(basic_plugin_4): (nil)
  5(basic_plugin_5): (nil)
  6(basic_plugin_6): (nil)
  7(basic_plugin_7): (nil)
  8(basic_plugin_8): (nil)
  9(basic_plugin_9): (nil)
  10(basic_plugin_10): (nil)
  11(basic_plugin_11): 0x16a8048 (basic_plugin_11)
cc1: error: plugin basic_plugin_1 should be specified before
-fplugin-arg-basic_plugin_1-enable in the command line
(null):0: confused by earlier errors, bailing out
make: *** [Makefile:12: test] Error 1
```

Please note that depending on your system and your luck, you might actually be
able to have collisions in the hash...