.opam-switch/environment file format is ambiguous and can lead to errors

[lefessan]

Currently, the .opam-switch/environment file is wrongly parsed by opam when the value of a variable is empty:

If my file is

CPP     =               Updated\ by\ package\ ocaml-base-compiler

CPP will wrongly be set to Updated by package ocaml-base-compiler. This will prevent creating another switch after eval $(opam env) because ocaml will fail to compile with a wrong CPP var.

An immediate fix should be to stop writing these "Updated by package $name" comments. A long-term fix should be to use a more standard format.

[dra27]

Which version of opam?

[dra27]

This rang a bell, and some digging reveals that I hit this years ago and fixed it in dra27@246b518, however that commit seems to have got lost in my myriad rebasing during the opam 2.0 cycle. My solution in that was to encode "" as @ and "@" as \@. The lexer was updated to recognise the single token @ as meaning "" - no handling is needed for \@ since that's dealt with automatically by the line lexer already.

[dra27]

I agree that the format could be changed; the comment is useful though.