Add fish shell support (#9279)

* share/spack/setup-env.fish file to setup environment in fish shell

* setup-env.fish testing script

* Update share/spack/setup-env.fish

Co-Authored-By: Elsa Gonsiorowski, PhD <gonsie@me.com>

* Update share/spack/qa/setup-env-test.fish

Co-Authored-By: Adam J. Stewart <ajstewart426@gmail.com>

* updates completions using `spack commands --update-completion`

* added stderr-nocaret warning

* added fish shell tests to CI system


Co-authored-by: becker33 <becker33@llnl.gov>
Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>
Co-authored-by: Elsa Gonsiorowski, PhD <gonsie@me.com>

lib/spack/spack/cmd/env.py

@@ -52,6 +52,9 @@ def env_activate_setup_parser(subparser):
     shells.add_argument(
         '--csh', action='store_const', dest='shell', const='csh',
         help="print csh commands to activate the environment")
+    shells.add_argument(
+        '--fish', action='store_const', dest='shell', const='fish',
+        help="print fish commands to activate the environment")
 
     view_options = subparser.add_mutually_exclusive_group()
     view_options.add_argument(
@@ -127,6 +130,9 @@ def env_deactivate_setup_parser(subparser):
     shells.add_argument(
         '--csh', action='store_const', dest='shell', const='csh',
         help="print csh commands to deactivate the environment")
+    shells.add_argument(
+        '--fish', action='store_const', dest='shell', const='fish',
+        help="print fish commands to activate the environment")
 
 
 def env_deactivate(args):

lib/spack/spack/cmd/load.py

@@ -32,6 +32,9 @@ def setup_parser(subparser):
     shells.add_argument(
         '--csh', action='store_const', dest='shell', const='csh',
         help="print csh commands to load the package")
+    shells.add_argument(
+        '--fish', action='store_const', dest='shell', const='fish',
+        help="print fish commands to load the package")
 
     subparser.add_argument(
         '--first',

lib/spack/spack/cmd/unload.py

@@ -31,6 +31,9 @@ def setup_parser(subparser):
     shells.add_argument(
         '--csh', action='store_const', dest='shell', const='csh',
         help="print csh commands to activate the environment")
+    shells.add_argument(
+        '--fish', action='store_const', dest='shell', const='fish',
+        help="print fish commands to load the package")
 
     subparser.add_argument('-a', '--all', action='store_true',
                            help='unload all loaded Spack packages.')

lib/spack/spack/environment.py

@@ -115,7 +115,7 @@ def activate(
         use_env_repo (bool): use the packages exactly as they appear in the
             environment's repository
         add_view (bool): generate commands to add view to path variables
-        shell (string): One of `sh`, `csh`.
+        shell (string): One of `sh`, `csh`, `fish`.
         prompt (string): string to add to the users prompt, or None
 
     Returns:
@@ -141,6 +141,19 @@ def activate(
             cmds += 'if (! $?SPACK_OLD_PROMPT ) '
             cmds += 'setenv SPACK_OLD_PROMPT "${prompt}";\n'
             cmds += 'set prompt="%s ${prompt}";\n' % prompt
+    elif shell == 'fish':
+        if os.getenv('TERM') and 'color' in os.getenv('TERM') and prompt:
+            prompt = colorize('@G{%s} ' % prompt, color=True)
+
+        cmds += 'set -gx SPACK_ENV %s;\n' % env.path
+        cmds += 'function despacktivate;\n'
+        cmds += '   spack env deactivate;\n'
+        cmds += 'end;\n'
+        #
+        # NOTE: We're not changing the fish_prompt function (which is fish's
+        # solution to the PS1 variable) here. This is a bit fiddly, and easy to
+        # screw up => spend time reasearching a solution. Feedback welcome.
+        #
     else:
         if os.getenv('TERM') and 'color' in os.getenv('TERM') and prompt:
             prompt = colorize('@G{%s} ' % prompt, color=True)
@@ -156,6 +169,12 @@ def activate(
             cmds += 'fi;\n'
             cmds += 'export PS1="%s ${PS1}";\n' % prompt
 
+    #
+    # NOTE in the fish-shell: Path variables are a special kind of variable
+    # used to support colon-delimited path lists including PATH, CDPATH,
+    # MANPATH, PYTHONPATH, etc. All variables that end in PATH (case-sensitive)
+    # become PATH variables.
+    #
     if add_view and default_view_name in env.views:
         with spack.store.db.read_transaction():
             cmds += env.add_default_view_to_shell(shell)
@@ -167,7 +186,7 @@ def deactivate(shell='sh'):
     """Undo any configuration or repo settings modified by ``activate()``.
 
     Arguments:
-        shell (string): One of `sh`, `csh`. Shell style to use.
+        shell (string): One of `sh`, `csh`, `fish`. Shell style to use.
 
     Returns:
         (string): shell commands for `shell` to undo environment variables
@@ -191,6 +210,12 @@ def deactivate(shell='sh'):
         cmds += 'set prompt="$SPACK_OLD_PROMPT" && '
         cmds += 'unsetenv SPACK_OLD_PROMPT;\n'
         cmds += 'unalias despacktivate;\n'
+    elif shell == 'fish':
+        cmds += 'set -e SPACK_ENV;\n'
+        cmds += 'functions -e despacktivate;\n'
+        #
+        # NOTE: Not changing fish_prompt (above) => no need to restore it here.
+        #
     else:
         cmds += 'if [ ! -z ${SPACK_ENV+x} ]; then\n'
         cmds += 'unset SPACK_ENV; export SPACK_ENV;\n'

lib/spack/spack/util/environment.py

@@ -32,12 +32,14 @@
 _shell_set_strings = {
     'sh': 'export {0}={1};\n',
     'csh': 'setenv {0} {1};\n',
+    'fish': 'set -gx {0} {1};\n'
 }
 
 
 _shell_unset_strings = {
     'sh': 'unset {0};\n',
     'csh': 'unsetenv {0};\n',
+    'fish': 'set -e {0};\n',
 }