Clearer diagnostics, no output after an error, and two UBSan fixes.

[glampert]

Four small changes, one commit each. This change only affects diagnostics and simple Sanitizer fixes.

1. Errors are now tagged error:, as warnings are tagged warning:. Errors were printed as file(line) : message, so searching a build log for "error:" found nothing, and a failed VU build was easy to miss. Now:
x.vcl(8) : error: Invalid argument (clipw.xyz fA, >>> fA[x] <<< [x ])
Errors without a location read openvcl: error: ....

2. Running out of registers names the variable. The message was only openvcl: Register allocation ran out of registers. It now gives the register type, how many registers .init_vf/.init_vi leave to the allocator, and the first line that uses the variable that couldn't be placed:
x.vcl(9) : error: Register allocation ran out of VI registers (2 available) for iC (ilw.x >>> iC <<<, 2(vi00))
For example, Tyra's stapip_cull_td_vu1, which only SCE vcl compiles, now accurately reports running out of VF registers (31 available) for outputColor3 at its line 171.

3. A failed build writes no output. When tokenizing reported an error, openvcl exited with failure but still wrote the .vsm, minus the bad instruction. The fresh file looked up to date to make, so the next build used it. Now nothing is written once an error has been reported, to a file or to stdout, and an existing output file is left as it was.

4. Two UBSan fixes, found by building with -fsanitize=address,undefined and running the tests and the PS2 examples:

• Tokenizer's constructor never initialized m_newSyntax. Parser sets it before tokenizing, but the Tokenizer unit tests read it first. It now starts false.
• The gasp temp-file name computed (getpid() + rand()) << 8 as an int, which overflows. It's now computed unsigned, which gives the same bits and so the same names.

Testing

• New test/integration/test_diagnostics.cpp, 5 new test cases.
• The full suite passes, also under ASan/UBSan, with no sanitizer reports.
• Across 48 VU programs (the ps2gl fixtures, the examples, Quake II and Tyra), the generated code is byte-identical to master.
• Merges cleanly with Check that instruction immediates fit their encoding; Add warnings-as-errors option. #3, and the two together pass all tests.

🤖 Co-authored by Claude Code