unikernel/duniverse/dune_/test/blackbox-tests/test-cases/root-module.t

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+A library can be shadowed by an internal module name:
+
+  $ cat >dune-project <<EOF
+  > (lang dune 2.8)
+  > EOF
+
+  $ mkdir lib0 lib1 lib2
+
+  $ cat >lib0/dune <<EOF
+  > (library
+  >  (name lib0))
+  > EOF
+  $ cat >lib0/lib0.ml <<EOF
+  > let greeting_from_lib0 = "Hello World"
+  > EOF
+
+  $ cat >lib1/dune <<EOF
+  > (library
+  >  (name lib1))
+  > EOF
+  $ cat >lib1/lib1.ml <<EOF
+  > let greeting = "Hello World"
+  > EOF
+
+  $ cat >lib2/dune <<EOF
+  > (library
+  >  (libraries lib1)
+  >  (name lib2))
+  > EOF
+
+Now we shadow lib1:
+  $ cat >lib2/lib1.ml <<EOF
+  > let greeting = ()
+  > EOF
+  $ cat >lib2/lib2.ml <<EOF
+  > print_endline Lib1.greeting
+  > EOF
+
+  $ dune build @all
+  File "lib2/lib2.ml", line 1, characters 14-27:
+  1 | print_endline Lib1.greeting
+                    ^^^^^^^^^^^^^
+  Error: The value Lib1.greeting has type unit
+         but an expression was expected of type string
+  [1]
+
+We can use the rename dependency type to use lib1 with a different name:
+
+  $ cat >lib2/dune <<EOF
+  > (library
+  >  (libraries lib1 unix)
+  >  (root_module root)
+  >  (name lib2))
+  > EOF
+  $ cat >lib2/lib2.ml <<EOF
+  > module U = UnixLabels
+  > let () = print_endline Root.Lib1.greeting
+  > EOF
+  $ dune build @all
+
+The same for executables:
+
+  $ mkdir exe
+  $ cat >exe/dune <<EOF
+  > (executable
+  >  (name foo)
+  >  (libraries lib1)
+  >  (root_module root))
+  > EOF
+  $ echo >exe/lib1.ml <<EOF
+  > let greeting = ()
+  > EOF
+  $ cat >exe/foo.ml <<EOF
+  > print_endline Root.Lib1.greeting
+  > EOF
+  $ dune exec ./exe/foo.exe
+  Hello World