Stop polluting PATH with Cygwin bin directory on Windows#1069
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Stop polluting PATH with Cygwin bin directory on Windows#1069
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Now that opam manages Cygwin internally via --cygwin-internal-install, there is no need to add CYGWIN_ROOT_BIN to the global PATH or to configure BASH_ENV with igncr. Removing these avoids shadowing the default MSYS2 bash with Cygwin's bash, which could break subsequent workflow steps that use `shell: bash`. Closes #1008
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smorimoto
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PR #1069 removed core.addPath(CYGWIN_ROOT_BIN) to stop Cygwin's bash from shadowing MSYS2 bash, but this also removed all Cygwin utilities from PATH, breaking downstream projects that depend on them. Instead of prepending with core.addPath() (which always prepends), use core.exportVariable("PATH", ...) to append Cygwin bin to the end of PATH. This keeps MSYS2 bash as the default shell whilst ensuring Cygwin utilities remain accessible. Closes #1084
smorimoto
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Mar 23, 2026
PR #1069 removed core.addPath(CYGWIN_ROOT_BIN) to stop Cygwin's bash from shadowing MSYS2 bash, but this also removed all Cygwin utilities from PATH, breaking downstream projects that depend on them. Instead of prepending with core.addPath() (which always prepends), use core.exportVariable("PATH", ...) to append Cygwin bin to the end of PATH. This keeps MSYS2 bash as the default shell whilst ensuring Cygwin utilities remain accessible. The BASH_ENV / igncr configuration is also removed as MSYS2 bash handles line endings on its own. Closes #1084
smorimoto
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PR #1069 removed core.addPath(CYGWIN_ROOT_BIN) unconditionally to fix #1008 (Cygwin bash shadowing MSYS2 bash), but this also broke downstream projects that depend on Cygwin utilities and Cygwin bash for /cygdrive/ path resolution. The original code lacked a WINDOWS_ENVIRONMENT guard, so even msys2 users were affected. The real fix is to restore the original behaviour but only when windows-environment is set to cygwin. Closes #1084
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Summary
core.addPath(CYGWIN_ROOT_BIN)which was prepending the Cygwin bin directory to PATH on Windows, causing Cygwin's bash to shadow the default MSYS2 bash in subsequent workflow stepsBASH_ENV/set -o igncrconfiguration that was only needed when Cygwin's bash was in PATHCYGWIN_ROOT,CYGWIN_ROOT_BIN, andCYGWIN_BASH_ENVconstantsSince the recent switch to
--cygwin-internal-install, opam manages its own Cygwin environment internally, so there is no longer any need to expose Cygwin on the global PATH.Closes #1008
Test plan
opam installand OCaml compilation still work correctly on Windows runnersshell: bashsteps after setup-ocaml use MSYS2 bash (not Cygwin bash)C:\.opam\.cygwin\root\binafter the action completes