Make subcommands modify $status, and make builtin_set not modify status unless it fails

fish-shell#547
fish-shell#214

Author: ridiculousfish

autoload.cpp

@@ -358,11 +358,9 @@ bool autoload_t::locate_file_and_maybe_load_it(const wcstring &cmd, bool really_
     /* If we have a script, either built-in or a file source, then run it */
     if (really_load && has_script_source)
     {
-        if (exec_subshell(script_source) == -1)
+        if (exec_subshell(script_source, false /* do not apply exit status */) == -1)
         {
-            /*
-              Do nothing on failiure
-            */
+            /* Do nothing on failure */
         }
 
     }

builtin.cpp

@@ -215,7 +215,7 @@ wcstring builtin_help_get(parser_t &parser, const wchar_t *name)
     wcstring out;
     const wcstring name_esc = escape_string(name, 1);
     const wcstring cmd = format_string(L"__fish_print_help %ls", name_esc.c_str());
-    if (exec_subshell(cmd, lst) >= 0)
+    if (exec_subshell(cmd, lst, false /* don't apply exit status */) >= 0)
     {
         for (size_t i=0; i<lst.size(); i++)
         {

builtin_set.cpp

@@ -379,58 +379,21 @@ static void print_variables(int include_values, int esc, bool shorten_ok, int sc
 */
 static int builtin_set(parser_t &parser, wchar_t **argv)
 {
-
-    /**
-       Variables used for parsing the argument list
-    */
-    static const struct woption
-            long_options[] =
+    /** Variables used for parsing the argument list */
+    const struct woption long_options[] =
     {
-        {
-            L"export", no_argument, 0, 'x'
-        }
-        ,
-        {
-            L"global", no_argument, 0, 'g'
-        }
-        ,
-        {
-            L"local", no_argument, 0, 'l'
-        }
-        ,
-        {
-            L"erase", no_argument, 0, 'e'
-        }
-        ,
-        {
-            L"names", no_argument, 0, 'n'
-        }
-        ,
-        {
-            L"unexport", no_argument, 0, 'u'
-        }
-        ,
-        {
-            L"universal", no_argument, 0, 'U'
-        }
-        ,
-        {
-            L"long", no_argument, 0, 'L'
-        }
-        ,
-        {
-            L"query", no_argument, 0, 'q'
-        }
-        ,
-        {
-            L"help", no_argument, 0, 'h'
-        }
-        ,
-        {
-            0, 0, 0, 0
-        }
-    }
-    ;
+        { L"export", no_argument, 0, 'x' },
+        { L"global", no_argument, 0, 'g' },
+        { L"local", no_argument, 0, 'l' },
+        { L"erase", no_argument, 0, 'e' },
+        { L"names", no_argument, 0, 'n' },
+        { L"unexport", no_argument, 0, 'u' },
+        { L"universal", no_argument, 0, 'U' },
+        { L"long", no_argument, 0, 'L' },
+        { L"query", no_argument, 0, 'q' },
+        { L"help", no_argument, 0, 'h' },
+        { 0, 0, 0, 0 }
+    } ;
 
     const wchar_t *short_options = L"+xglenuULqh";
 
@@ -443,6 +406,8 @@ static int builtin_set(parser_t &parser, wchar_t **argv)
     int erase = 0, list = 0, unexport=0;
     int universal = 0, query=0;
     bool shorten_ok = true;
+    bool preserve_incoming_failure_exit_status = true;
+    const int incoming_exit_status = proc_get_last_status();
 
     /*
       Variables used for performing the actual work
@@ -474,10 +439,12 @@ static int builtin_set(parser_t &parser, wchar_t **argv)
 
             case 'e':
                 erase = 1;
+                preserve_incoming_failure_exit_status = false;
                 break;
 
             case 'n':
                 list = 1;
+                preserve_incoming_failure_exit_status = false;
                 break;
 
             case 'x':
@@ -506,6 +473,7 @@ static int builtin_set(parser_t &parser, wchar_t **argv)
 
             case 'q':
                 query = 1;
+                preserve_incoming_failure_exit_status = false;
                 break;
 
             case 'h':
@@ -825,6 +793,8 @@ static int builtin_set(parser_t &parser, wchar_t **argv)
 
     free(dest);
 
+    if (retcode == STATUS_BUILTIN_OK && preserve_incoming_failure_exit_status)
+        retcode = incoming_exit_status;
     return retcode;
 
 }

color.h

@@ -135,7 +135,7 @@ class rgb_color_t
     /** Returns whether the color is bold */
     bool is_bold() const
     {
-        return !! (flags & flag_bold);
+        return !!(flags & flag_bold);
     }
 
     /** Set whether the color is bold */

common.h

@@ -150,7 +150,7 @@ extern const wchar_t *program_name;
 		read( 0, &exit_read_buff, 1 );			\
 		exit_without_destructors( 1 );												\
 	}															\
-
+ 
 
 /**
    Exit program at once, leaving an error message about running out of memory.

complete.cpp

@@ -465,7 +465,7 @@ bool completer_t::condition_test(const wcstring &condition)
     if (cached_entry == condition_cache.end())
     {
         /* Compute new value and reinsert it */
-        test_res = (0 == exec_subshell(condition));
+        test_res = (0 == exec_subshell(condition, false /* don't apply exit status */));
         condition_cache[condition] = test_res;
     }
     else
@@ -1007,7 +1007,7 @@ void completer_t::complete_cmd_desc(const wcstring &str)
       since apropos is only called once.
     */
     wcstring_list_t list;
-    if (exec_subshell(lookup_cmd, list) != -1)
+    if (exec_subshell(lookup_cmd, list, false /* don't apply exit status */) != -1)
     {
 
         /*

doc_src/fish_prompt.txt

@@ -11,8 +11,7 @@ By defining the \c fish_prompt function, the user can choose a custom
 prompt. The \c fish_prompt function is executed when the prompt is to
 be shown, and the output is used as a prompt.
 
-Please keep in mind that the function is executed by <a
-href='index.html#expand-command-substitution'>command substitution</a>, and so the exit status of commands within fish_prompt will not modify the <a href="index.html#variables-status">$status</a> seen outside of fish_prompt.
+The exit status of commands within \c fish_prompt will not modify the <a href="index.html#variables-status">$status</a> seen outside of fish_prompt.
 
 \subsection fish_prompt-example Example
 

doc_src/index.hdr.in

@@ -578,9 +578,8 @@ this list is executed, and substituted by the output. If the output is
 more than one line long, each line will be expanded to a new
 parameter.
 
-A command substitution will not change the value of the <a
-href='#variables-status'>status</a> variable outside of the command
-substitution.
+The exit status of the last run command substitution is available in the <a
+href='#variables-status'>status</a> variable.
 
 Only part of the output can be used, see <a href='#expand-index-range'>index
 range expansion</a> for details.

doc_src/set.txt

@@ -68,13 +68,14 @@ non-switch arguments. For example, <code>set flags -l</code> will have
 the effect of setting the value of the variable <code>flags</code> to
 '-l', not making the variable local.
 
-In assignment mode, set exits with an exit status of zero it the
-variable assignments where sucessfully performed, with a non-zero exit
-status otherwise. In query mode, the exit status is the number of
-variables that where not found. In erase mode, set exits with a zero
-exit status in case of success, with a non-zero exit status if the
-commandline was invalid, if the variable was write-protected or if the
-variable did not exist.
+In assignment mode, set exits with a non-zero exit status if variable
+assignments could not be successfully performed. If the variable assignments
+were performed, the exit status is unchanged. This allows simultaneous capture
+of the output and exit status of a subcommand, e.g. <code>if set output
+(command)</code>. In query mode, the exit status is the number of variables that
+were not found. In erase mode, set exits with a zero exit status in case of
+success, with a non-zero exit status if the commandline was invalid, if the
+variable was write-protected or if the variable did not exist.
 
 \subsection set-example Example
 
@@ -85,3 +86,9 @@ variable did not exist.
 <code>set -e smurf</code> removes the variable \c smurf.
 
 <code>set PATH[4] ~/bin</code> changes the fourth element of the \c PATH array to \c ~/bin
+
+<pre>if set python_path (which python)
+    echo "Python is at $python_path"
+end</pre>
+
+The above outputs the path to Python if \c which returns true.