cmd/go: pass in overlaid file paths to C compiler

This change moves the code in work.(*Builder).cgo that, when there is
an overlay, copies non-Go files to objdir into work.(*Builder).Build,
and creates an overlay structure mapping from the nominal file paths
into the copies in objdir. That's propagated through to
work.(*Builder).ccompile, which will use it to pass in the path to the
overlaid contents in objdir when calling the compiler.

This allows for overlays of C/C++/Fortran files.

For #39958

Change-Id: I9a2e3d3ba6afdf7ce19be1dbf4eee34805cdc05f
Trust: Michael Matloob <>
Run-TryBot: Michael Matloob <>
TryBot-Result: Go Bot <>
Reviewed-by: Jay Conrod <>
Reviewed-by: Bryan C. Mills <>
3 files changed
tree: 76fb86eafacd4765c5de7d68a66dcf65af6573f6
  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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