Ignore errors while generating the .merlin file

Fix #568
Fix #51

src/merlin.ml

@@ -21,8 +21,9 @@ let make
       ?(source_dirs=Path.Set.empty)
       ?(objs_dirs=Path.Set.empty)
       () =
-  { requires
-  ; flags
+  (* Merlin shouldn't cause the build to fail, so we just ignore errors *)
+  { requires = Build.catch requires ~on_error:(fun _ -> [])
+  ; flags    = Build.catch flags    ~on_error:(fun _ -> [])
   ; preprocess
   ; libname
   ; source_dirs

test/blackbox-tests/test-cases/github25/root/run.t

@@ -14,11 +14,11 @@ We need ocamlfind to run this test
       ocamlopt hello.cmxs
 
   $ $JBUILDER build -j1 @install --display short --root . --only pas-de-bol 2>&1 | sed 's/[^ "]*findlib-packages/.../'
+      ocamldep a.ml.d
   File ".../plop/META", line 1, characters 0-0:
   Error: Library "une-lib-qui-nexiste-pas" not found.
   -> required by library "plop.ca-marche-pas" in .../plop
   Hint: try: jbuilder external-lib-deps --missing --root . --only-packages pas-de-bol @install
-      ocamldep a.ml.d
       ocamldep b.ml.d
         ocamlc .pas_de_bol.objs/pas_de_bol.{cmi,cmo,cmt}
       ocamlopt .pas_de_bol.objs/pas_de_bol.{cmx,o}

test/blackbox-tests/test-cases/github568/run.t

@@ -1,12 +1,10 @@
   $ $JBUILDER runtest --display short -j1 -p lib1 --debug-dependency-path
-  File "jbuild", line 1, characters 0-464:
-  Error: Library "lib2" not found.
-  -> required by .merlin
-  -> required by .merlin-exists
-  -> required by test1.exe
-  -> required by alias runtest
-  -> required by alias runtest
-  Hint: try: jbuilder external-lib-deps --missing -p lib1 @runtest
       ocamldep test1.ml.d
       ocamldep lib1.ml.d
-  [1]
+        ocamlc .lib1.objs/lib1.{cmi,cmo,cmt}
+        ocamlc .test1.eobjs/test1.{cmi,cmo,cmt}
+      ocamlopt .lib1.objs/lib1.{cmx,o}
+      ocamlopt .test1.eobjs/test1.{cmx,o}
+      ocamlopt lib1.{a,cmxa}
+      ocamlopt test1.exe
+         test1 alias runtest