unikernel/duniverse/dune_/test/blackbox-tests/test-cases/install/install-stublibs-shadow.t

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+This test shows that when libraries `libA` and `libB` containing both C stubs
+are installed, and a bytecode executable `exeA` that depends on a local version
+of `libA` and the installed version of `libB` is being built, then the C stubs
+from the installed `libA` (on which `exeA` does not depend) are put in the load
+path and take precendence over the local copy of `libA`.
+
+See https://github.com/ocaml/dune/issues/9979.
+
+Begin by installing libraries `libA` and `libB` with C stubs.
+
+  $ cat >dune-project <<EOF
+  > (lang dune 3.13)
+  > (package (name pkgA))
+  > EOF
+  $ cat >libA.ml <<EOF
+  > EOF
+  $ cat >libB.ml <<EOF
+  > EOF
+  $ cat >dune <<EOF
+  > (library
+  >  (name libA)
+  >  (public_name pkgA.libA)
+  >  (foreign_stubs
+  >   (language c)
+  >   (names stubsA))
+  >  (modules libA))
+  > (library
+  >  (name libB)
+  >  (public_name pkgA.libB)
+  >  (foreign_stubs
+  >   (language c)
+  >   (names stubsB))
+  >  (modules libB))
+  > EOF
+  $ cat >stubsA.c <<EOF
+  > int dummy0() { return 0; }
+  > EOF
+  $ cat >stubsB.c <<EOF
+  > int dummy1() { return 0; }
+  > EOF
+  $ dune build
+  $ dune install --prefix ./install --display short 2>&1 | grep \\.so
+  Installing install/lib/stublibs/dlllibA_stubs.so
+  Installing install/lib/stublibs/dlllibB_stubs.so
+
+And we try to build an executable depending on the (local) `libA` and the (installed) `libB`:
+
+  $ mkdir -p libA
+  $ cat >libA/libA.ml <<EOF
+  > external f : int -> int = "dummy2"
+  > EOF
+  $ cat >libA/stubs.c <<EOF
+  > int dummy2() { return 0; }
+  > EOF
+  $ cat >exeA.ml <<EOF
+  > let _ = LibA.f
+  > EOF
+  $ cat >libA/dune <<EOF
+  > (library
+  >  (name libA)
+  >  (foreign_stubs
+  >   (language c)
+  >   (names stubs))
+  >  (modules libA))
+  > EOF
+  $ cat >dune <<EOF
+  > (executable
+  >  (name exeA)
+  >  (modes byte)
+  >  (libraries pkgA.libB libA)
+  >  (modules exeA))
+  > EOF
+
+  $ OCAMLPATH=./install/lib dune build exeA.bc
+  File "_none_", line 1:
+  Error: Error while linking .exeA.eobjs/byte/dune__exe__ExeA.cmo:
+         The external function dummy2 is not available
+  [1]
+
+The error comes from passing as flags `-I ./install/lib/pkgA/../stublibs -I
+libA` so the `dlllibA_stubs.so` in `./install/lib/stublibs` takes precedence
+over the one in `libA`.
+
+If we list `libA` __before__ `pkgA.libB`, the build succeeds because the include
+flags look like `-I libA -I ./install/lib/pkgA/../stublibs`:
+
+  $ cat >dune <<EOF
+  > (executable
+  >  (name exeA)
+  >  (modes byte)
+  >  (libraries libA pkgA.libB)
+  >  (modules exeA))
+  > EOF
+
+  $ OCAMLPATH=./install/lib dune build exeA.bc