Skip variable assignments in status current command

Fixes #6635

(cherry picked from commit aa0e16b1a5)

src/builtin_fg.cpp

@@ -98,7 +98,7 @@ int builtin_fg(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
         std::fwprintf(stderr, FG_MSG, job->job_id(), job->command_wcstr());
     }
 
-    const wcstring ft = tok_first(job->command());
+    const wcstring ft = tok_command(job->command());
     // For compatibility with fish 2.0's $_, now replaced with `status current-command`
     if (!ft.empty()) parser.vars().set_one(L"_", ENV_EXPORT, ft);
     reader_write_title(job->command(), parser);

src/reader.cpp

@@ -1943,7 +1943,7 @@ void set_env_cmd_duration(struct timeval *after, struct timeval *before, env_sta
 void reader_run_command(parser_t &parser, const wcstring &cmd) {
     struct timeval time_before, time_after;
 
-    wcstring ft = tok_first(cmd);
+    wcstring ft = tok_command(cmd);
 
     // For compatibility with fish 2.0's $_, now replaced with `status current-command`
     if (!ft.empty()) parser.vars().set_one(L"_", ENV_GLOBAL, ft);

src/tokenizer.cpp

@@ -663,6 +663,21 @@ wcstring tok_first(const wcstring &str) {
     return {};
 }
 
+wcstring tok_command(const wcstring &str) {
+    tokenizer_t t(str.c_str(), 0);
+    while (auto token = t.next()) {
+        if (token->type != token_type_t::string) {
+            return {};
+        }
+        wcstring text = t.text_of(*token);
+        if (variable_assignment_equals_pos(text)) {
+            continue;
+        }
+        return text;
+    }
+    return {};
+}
+
 bool move_word_state_machine_t::consume_char_punctuation(wchar_t c) {
     enum { s_always_one = 0, s_rest, s_whitespace_rest, s_whitespace, s_alphanumeric, s_end };
 

src/tokenizer.h

@@ -144,6 +144,9 @@ class tokenizer_t {
 /// returns the empty string.
 wcstring tok_first(const wcstring &str);
 
+/// Like to tok_first, but skip variable assignments like A=B.
+wcstring tok_command(const wcstring &str);
+
 /// Struct wrapping up a parsed pipe or redirection.
 struct pipe_or_redir_t {
     // The redirected fd, or -1 on overflow.

tests/status.in

@@ -37,6 +37,9 @@ status job-control none
 # Check status -u outside functions
 status current-function
 
+a=b status current-command
+#CHECK: status
+
 function test_function
     status current-function
 end