fish_key_reader: Add --version option

This should be there anyway, and we try to find fish_key_reader for
.app bundles, so this stops us from defining aliases to the command.

See #4179.

doc_src/fish_key_reader.txt

@@ -21,6 +21,8 @@ The following options are available:
 
 - `-h` or `--help` prints usage information.
 
+- `-v` or `--version` prints fish_key_reader's version and exits.
+
 \subsection fish_key_reader-usage-notes Usage Notes
 
 The delay in milliseconds since the previous character was received is included in the diagnostic information written to stderr. This information may be useful to determine the optimal `fish_escape_delay_ms` setting or learn the amount of lag introduced by tools like `ssh`, `mosh` or `tmux`.

share/functions/fish_key_reader.fish

@@ -1,7 +1,7 @@
 # check if command fish_key_reader works and is the same version that
 # came with this fish. This will happen one time.
 command -sq fish_key_reader
-and command fish_key_reader --version 2>&1 | string match -rq $FISH_VERSION
+and command fish_key_reader --version 2>&1 | string match -q -- $FISH_VERSION
 # if alias doesn't define the function here, this is an autoloaded "nothing".
 # the command (if there is one) will be used by default.
 or alias fish_key_reader=(string escape $__fish_bin_dir/fish_key_reader)

src/fish_key_reader.cpp

@@ -26,6 +26,7 @@
 #include "common.h"
 #include "env.h"
 #include "fallback.h"  // IWYU pragma: keep
+#include "fish_version.h"
 #include "input.h"
 #include "input_common.h"
 #include "print_help.h"
@@ -331,11 +332,12 @@ static bool parse_debug_frames_flag() {
 }
 
 static bool parse_flags(int argc, char **argv, bool *continuous_mode) {
-    const char *short_opts = "+cd:D:h";
+    const char *short_opts = "+cd:D:hv";
     const struct option long_opts[] = {{"continuous", no_argument, NULL, 'c'},
                                        {"debug-level", required_argument, NULL, 'd'},
                                        {"debug-stack-frames", required_argument, NULL, 'D'},
                                        {"help", no_argument, NULL, 'h'},
+                                       {"version", no_argument, NULL, 'v'},
                                        {NULL, 0, NULL, 0}};
     int opt;
     bool error = false;
@@ -358,6 +360,10 @@ static bool parse_flags(int argc, char **argv, bool *continuous_mode) {
                 error = !parse_debug_frames_flag();
                 break;
             }
+            case 'v': {
+                fwprintf(stdout, L"%s\n", get_fish_version());
+                return false;
+            }
             default: {
                 // We assume getopt_long() has already emitted a diagnostic msg.
                 error = true;