[clang][oops] restore previous functionality

Summary: The previous commit broke the `--foo arg` case because it matched `--foo` in the case looking for `--foo=`.

Reviewed By: mbouaziz

Differential Revision: D15670472

fbshipit-source-id: ab81c7357

infer/src/clang/ClangCommand.ml

@@ -124,8 +124,12 @@ let filter_and_replace_unsupported_args ?(replace_options_arg = fun _ s -> s) ?(
             aux in_argfiles' (false, at_argfile :: res_rev, changed) tl )
     | flag :: tl
       when List.mem ~equal:String.equal Config.clang_blacklisted_flags flag
-           || List.mem ~equal:String.equal Config.clang_blacklisted_flags_with_arg
-                (String.split ~on:'=' flag |> List.hd |> Option.value ~default:"") ->
+           || String.lsplit2 ~on:'=' flag
+              |> function
+              | Some (flag, _arg) ->
+                  List.mem ~equal:String.equal Config.clang_blacklisted_flags_with_arg flag
+              | None ->
+                  false ->
         aux in_argfiles (false, res_rev, true) tl
     | flag :: tl when List.mem ~equal:String.equal Config.clang_blacklisted_flags_with_arg flag ->
         (* remove the flag and its arg separately in case we are at the end of an argfile *)

infer/tests/build_systems/clang_with_blacklisted_flags/Makefile

@@ -10,8 +10,8 @@ TESTS_DIR = ../..
 # a folder, is not discarded, and Clang considers it as a source file. This
 # leads to an error. This weird case can be observed when -index-store-path is
 # passed in a sequence like the one in CLANG_OPTIONS.
-CLANG_OPTIONS = -x c -index-store-path . -c -fsanitize=builtin -fsanitize=address,builtin
-INFER_OPTIONS = --report-custom-error --developer-mode --project-root ../codetoanalyze
+CLANG_OPTIONS = -x c -index-store-path . -c -fsanitize=builtin -fsanitize=address,builtin -bogus=arg
+INFER_OPTIONS = --report-custom-error --developer-mode --project-root ../codetoanalyze --clang-blacklisted-flags-with-arg -bogus
 INFERPRINT_OPTIONS = --issues-tests
 
 SOURCES = ../codetoanalyze/hello.c