pkg: repro for gh10670 (#10672)

Signed-off-by: Stephen Sherratt <[email protected]>

Author: gridbugs

test/blackbox-tests/test-cases/pkg/gh10670.t

@@ -0,0 +1,44 @@
+Reproduces https://github.com/ocaml/dune/issues/10670
+
+Dune solves packages with "post" set to false, so the disjunction in
+ocaml-base-compiler's dependencies can't be resolved on non-windows
+systems.
+
+  $ . ./helpers.sh
+  $ mkrepo
+
+  $ cat >dune-workspace << EOF
+  > (lang dune 3.16)
+  > (lock_dir
+  >  (path dune.lock)
+  >  (repositories mock)
+  >  (solver_env
+  >   (os linux)))
+  > EOF
+
+  $ mkpkg host-system-other
+
+  $ mkpkg system-mingw << EOF
+  > available: os = "win32"
+  > EOF
+
+  $ mkpkg ocaml-base-compiler << EOF
+  > depends: [
+  >   (("arch-x86_64" {os = "win32" & arch = "x86_64"} & "system-mingw" &
+  >     "mingw-w64-shims" {os-distribution = "cygwin" & build}) |
+  >    ("arch-x86_32" {os = "win32"} & "ocaml-option-bytecode-only" &
+  >     "system-mingw" &
+  >     "mingw-w64-shims" {os-distribution = "cygwin" & build}) |
+  >    "host-system-other" {os != "win32" & post})
+  > ]
+  > EOF
+
+  $ solve ocaml-base-compiler 
+  Error: Unable to solve dependencies for the following lock directories:
+  Lock directory dune.lock:
+  Can't find all required versions.
+  Selected: ocaml-base-compiler.0.0.1 x.dev system-mingw
+  - system-mingw -> (problem)
+      No usable implementations:
+        system-mingw.0.0.1: Availability condition not satisfied
+  [1]