cmd/cgo: ensure GCC does not use ANSI escape sequences in errors

cgo parses GCC’s error messages to classify C identifiers referenced
from Go programs (are they integer constants? type names?). If GCC tries
to colorize its errors, cgo can’t figure out what GCC is saying. GCC
avoids escape sequences in this scenario by default, but the default
behavior can be overridden in at least two places:

  - The user can set `CGO_COPTS=-fdiagnostics-color`.

  - Whoever compiled GCC can configure GCC itself to always colorize

The most reliable way to ensure that GCC doesn’t colorize output is to
append `-fdiagnostics-color=never` to the GCC command line; do so.

Fixes #40415

Change-Id: Id4bdf8d92fac8b038340b4264f726e8fe38875b4
Run-TryBot: Ian Lance Taylor <>
TryBot-Result: Gobot Gobot <>
Reviewed-by: Ian Lance Taylor <>
2 files changed
tree: ddf2bfb6b542e7cc57fbac93edf32532f3e0d1aa
  1. .gitattributes
  2. .github/
  3. .gitignore
  11. api/
  12. doc/
  13. favicon.ico
  14. lib/
  15. misc/
  16. robots.txt
  17. src/
  18. test/

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