After an effort spanning several years, we should now be warning-free
on all major compilers, so we can set `-Werror` to ensure that we don't
introduce warnings in new code.
Disable -Werror=strict-overflow on GCC 7 though, as it seems bogus and
was fixed in 8+.
Configured for a max line length of 120 characters.
psf/black is very opinionated and purposely doesn't leave much room for
configuration. The output is mostly OK so that should be fine for us,
but some things worth noting:
- Manually wrapped strings will be reflowed, so by using a line length
of 120 for the sake of preserving readability for our long command
calls, it also means that some manually wrapped strings are back on
the same line and should be manually merged again.
- Code generators using string concatenation extensively look awful,
since black puts each operand on a single line. We need to refactor
these generators to use more pythonic string formatting, for which
many options are available (`%`, `format` or f-strings).
- CI checks and a pre-commit hook will be added to ensure that future
buildsystem changes are well-formatted.
Correct backtrack assignment to prevent excessive tabulation. Worth
noting that tabulation is treated differently in RichTextLabel because
of custom user-asignable tab variable which creates problems with
dynamic fonts specifically.
Namely:
```
modules/basis_universal/register_types.cpp: In function 'Ref<Image> basis_universal_unpacker(const Vector<unsigned char>&)':
modules/basis_universal/register_types.cpp:266:15: warning: 'imgfmt' may be used uninitialized in this function [-Wmaybe-uninitialized]
266 | image->create(info.m_width, info.m_height, info.m_total_levels > 1, imgfmt, gpudata);
| ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
modules/basis_universal/register_types.cpp:255:39: warning: 'format' may be used uninitialized in this function [-Wmaybe-uninitialized]
255 | bool ret = tr.transcode_image_level(ptr, size, 0, i, dst + ofs, level.m_total_blocks - i, format);
| ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```
```
servers/visual_server.cpp: In member function 'Error VisualServer::_surface_set_data(Array, uint32_t, uint32_t*, uint32_t, Vector<unsigned char>&, int, Vector<unsigned char>&, int, AABB&, Vector<AABB>&)':
servers/visual_server.cpp:636:15: warning: 'iw' may be used uninitialized in this function [-Wmaybe-uninitialized]
636 | copymem(&iw[i * 2], &v, 2);
| ^
```
```
core/image.cpp: In member function 'Error Image::generate_mipmap_roughness(Image::RoughnessChannel, const Ref<Image>&)':
core/image.cpp:1683:11: warning: 'roughness' may be used uninitialized in this function [-Wmaybe-uninitialized]
1683 | float roughness;
| ^~~~~~~~~
```
