Add compilation test for the new META field

Signed-off-by: Nicolás Ojeda Bär <n.oje.bar@gmail.com>

test/blackbox-tests/test-cases/meta-exports.t

@@ -0,0 +1,118 @@
+Check our handling of `exports` in META files. We begin with a test showing that
+we can *consume* META files containing an `exports` field.
+
+To do this, first we create a Findlib hierarchy containing two installed
+packages, `foo` and `bar`. The package `foo` is empty and only exists to
+re-export `bar`. The package `bar` consists of a bytecode library, `bar.cma`.
+
+  $ mkdir -p _install/foo
+  $ cat >_install/foo/META <<EOF
+  > requires = "bar"
+  > EOF
+
+  $ mkdir -p _install/bar
+  $ cat >_install/bar/META <<EOF
+  > archive(byte) = "bar.cma"
+  > EOF
+  $ cat >_install/bar/bar.ml <<EOF
+  > let x = 42
+  > EOF
+  $ ocamlc -a -o _install/bar/bar.cma _install/bar/bar.ml
+
+We now define a Dune project that will consume `foo`.
+
+  $ cat >dune-project <<EOF
+  > (lang dune 3.0)
+  > EOF
+
+  $ cat >dune <<EOF
+  > (executable
+  >  (name main)
+  >  (modes byte)
+  >  (libraries foo))
+  > EOF
+  $ cat >main.ml <<EOF
+  > let () = print_int Bar.x; print_newline ()
+  > EOF
+
+Compilation works with `(implicit_transitive_deps)`:
+
+  $ OCAMLPATH=$(pwd)/_install dune exec ./main.exe
+  42
+
+However, the compilation without `(implicit_transitive_deps)` fails:
+
+  $ cat >dune-project <<EOF
+  > (lang dune 3.0)
+  > (implicit_transitive_deps false)
+  > EOF
+
+  $ OCAMLPATH=$(pwd)/_install dune exec ./main.exe
+  File "main.ml", line 1, characters 19-24:
+  1 | let () = print_int Bar.x; print_newline ()
+                         ^^^^^
+  Error: Unbound module Bar
+  [1]
+
+Next, we add the `exports` field to `foo`'s `META` file:
+
+  $ cat >_install/foo/META <<EOF
+  > requires = "bar"
+  > exports = "bar"
+  > EOF
+
+and compilation now works again:
+
+  $ OCAMLPATH=$(pwd)/_install dune exec ./main.exe
+  42
+
+----------------------------------------------------------------
+
+Next, we check that we can *produce* META files with the `export` field.  To do
+this, we define two Dune libraries `foo` and `bar`, where `foo` depends on `bar`
+using `(re_export)`.
+
+  $ cat >dune-project.gen <<'EOF'
+  > cat <<EOF2
+  > (lang dune $VERSION)
+  > (package (name foo))
+  > (package (name bar))
+  > EOF2
+  > EOF
+
+  $ cat >dune <<EOF
+  > (library
+  >  (public_name bar)
+  >  (modules bar))
+  > (library
+  >  (public_name foo)
+  >  (libraries (re_export bar))
+  >  (modules foo))
+  > EOF
+  $ true >bar.ml
+  $ true >foo.ml
+
+First we try with dune version 3.16 (it should not generate the `exports` field):
+
+  $ VERSION=3.16 sh dune-project.gen >dune-project
+  $ dune build && dune install --libdir $(pwd)/_local
+  $ cat _local/foo/META
+  description = ""
+  requires = "bar"
+  archive(byte) = "foo.cma"
+  archive(native) = "foo.cmxa"
+  plugin(byte) = "foo.cma"
+  plugin(native) = "foo.cmxs"
+
+Now with dune version 3.17 (it should generate the `exports` field):
+
+  $ VERSION=3.17 sh dune-project.gen >dune-project
+  $ dune build && dune install --libdir $(pwd)/_local
+  $ cat _local/foo/META
+  description = ""
+  requires = "bar"
+  exports = "bar"
+  archive(byte) = "foo.cma"
+  archive(native) = "foo.cmxa"
+  plugin(byte) = "foo.cma"
+  plugin(native) = "foo.cmxs"

test/blackbox-tests/test-cases/meta-gen.t/dune

@@ -41,11 +41,6 @@
  (libraries foobar)
  (preprocess (pps foobar_rewriter)))
 
-(rule
- (alias runtest)
+(alias
+ (name runtest)
  (action (echo "%{read:META.foobar}")))
-
-(library
- (name foobar2)
- (public_name foobar.foobar2)
- (libraries (re_export foobar) (re_export foobar_ppd) foobar_rewriter2))

test/blackbox-tests/test-cases/meta-gen.t/dune-project

@@ -0,0 +1 @@
+(lang dune 1.9)

test/blackbox-tests/test-cases/meta-gen.t/run.t

@@ -1,4 +1,3 @@
-  $ echo '(lang dune 2.0)' > dune-project
   $ dune runtest --force
   description = "contains \"quotes\""
   requires = "bytes"
@@ -15,100 +14,6 @@
     plugin(byte) = "foobar_baz.cma"
     plugin(native) = ""
   )
-  package "foobar2" (
-    directory = "foobar2"
-    description = ""
-    requires = "foobar foobar.ppd foobar.rewriter2"
-    archive(byte) = "foobar2.cma"
-    archive(native) = "foobar2.cmxa"
-    plugin(byte) = "foobar2.cma"
-    plugin(native) = "foobar2.cmxs"
-  )
-  package "ppd" (
-    directory = "ppd"
-    description = "pp'd with a rewriter"
-    requires = "foobar foobar.baz foobar.runtime-lib2"
-    archive(byte) = "foobar_ppd.cma"
-    archive(native) = "foobar_ppd.cmxa"
-    plugin(byte) = "foobar_ppd.cma"
-    plugin(native) = "foobar_ppd.cmxs"
-  )
-  package "rewriter" (
-    directory = "rewriter"
-    description = "ppx rewriter"
-    requires(ppx_driver) = "foobar foobar.rewriter2"
-    archive(ppx_driver,byte) = "foobar_rewriter.cma"
-    archive(ppx_driver,native) = "foobar_rewriter.cmxa"
-    plugin(ppx_driver,byte) = "foobar_rewriter.cma"
-    plugin(ppx_driver,native) = "foobar_rewriter.cmxs"
-    # This is what dune uses to find out the runtime dependencies of
-    # a preprocessor
-    ppx_runtime_deps = "foobar.baz"
-    # This line makes things transparent for people mixing preprocessors
-    # and normal dependencies
-    requires(-ppx_driver) = "foobar.baz foobar.runtime-lib2"
-    ppx(-ppx_driver,-custom_ppx) = "./ppx.exe --as-ppx"
-    library_kind = "ppx_rewriter"
-  )
-  package "rewriter2" (
-    directory = "rewriter2"
-    description = "ppx rewriter expander"
-    requires = "foobar"
-    archive(byte) = "foobar_rewriter2.cma"
-    archive(native) = "foobar_rewriter2.cmxa"
-    plugin(byte) = "foobar_rewriter2.cma"
-    plugin(native) = "foobar_rewriter2.cmxs"
-    # This is what dune uses to find out the runtime dependencies of
-    # a preprocessor
-    ppx_runtime_deps = "foobar.runtime-lib2"
-  )
-  package "runtime-lib2" (
-    directory = "runtime-lib2"
-    description = "runtime library for foobar.rewriter2"
-    requires = ""
-    archive(byte) = "foobar_runtime_lib2.cma"
-    archive(native) = "foobar_runtime_lib2.cmxa"
-    plugin(byte) = "foobar_runtime_lib2.cma"
-    plugin(native) = "foobar_runtime_lib2.cmxs"
-    jsoo_runtime = "foobar_runtime.js foobar_runtime2.js"
-  )
-  package "sub" (
-    directory = "sub"
-    description = "sub library in a sub dir"
-    requires = "bytes"
-    archive(byte) = "foobar_sub.cma"
-    archive(native) = ""
-    plugin(byte) = "foobar_sub.cma"
-    plugin(native) = ""
-  )
-
-  $ echo '(lang dune 3.17)' > dune-project
-  $ dune runtest --force
-  description = "contains \"quotes\""
-  requires = "bytes"
-  archive(byte) = "foobar.cma"
-  archive(native) = "foobar.cmxa"
-  plugin(byte) = "foobar.cma"
-  plugin(native) = "foobar.cmxs"
-  package "baz" (
-    directory = "baz"
-    description = "sub library with modes set to byte"
-    requires = "bytes"
-    archive(byte) = "foobar_baz.cma"
-    archive(native) = ""
-    plugin(byte) = "foobar_baz.cma"
-    plugin(native) = ""
-  )
-  package "foobar2" (
-    directory = "foobar2"
-    description = ""
-    requires = "foobar foobar.ppd foobar.rewriter2"
-    exports = "foobar foobar.ppd"
-    archive(byte) = "foobar2.cma"
-    archive(native) = "foobar2.cmxa"
-    plugin(byte) = "foobar2.cma"
-    plugin(native) = "foobar2.cmxs"
-  )
   package "ppd" (
     directory = "ppd"
     description = "pp'd with a rewriter"