devenv: Implement prompt for fish and zsh

Co-authored-by: Nirbheek Chauhan <nirbheek@centricular.com>

Author: xclaesse

mesonbuild/mdevenv.py

@@ -6,6 +6,7 @@
 import shutil
 import sys
 import itertools
+import signal
 import typing as T
 
 from pathlib import Path
@@ -224,6 +225,26 @@ def run(options: argparse.Namespace) -> int:
             tmprc.flush()
             args.append("--rcfile")
             args.append(tmprc.name)
+        elif args[0].endswith('fish'):
+            # Ignore SIGINT while using fish as the shell to make it behave
+            # like other shells such as bash and zsh.
+            # See: https://gitlab.freedesktop.org/gstreamer/gst-build/issues/18
+            signal.signal(signal.SIGINT, lambda _, __: True)
+            if prompt_prefix:
+                args.append('--init-command')
+                prompt_cmd = f'''functions --copy fish_prompt original_fish_prompt
+                function fish_prompt
+                    echo -n '[{prompt_prefix}] '(original_fish_prompt)
+                end'''
+                args.append(prompt_cmd)
+        elif args[0].endswith('zsh'):
+            # Let the GC remove the tmp file
+            tmpdir = tempfile.TemporaryDirectory()
+            with open(os.path.join(tmpdir.name, '.zshrc'), 'w', encoding='utf-8') as zshrc:
+                zshrc.write('[ -e ~/.zshrc ] && . ~/.zshrc\n')
+                if prompt_prefix:
+                    zshrc.write(f'export PROMPT="[{prompt_prefix}] $PROMPT"\n')
+            devenv['ZDOTDIR'] = tmpdir.name
     else:
         # Try to resolve executable using devenv's PATH
         abs_path = shutil.which(args[0], path=devenv.get('PATH', None))