Add option "--first" for "spack load" (#15622)

* Implemented --first option for "spack load"

* added test for "spack load --first"

Co-authored-by: gragghia <gragghia@localhost.localdomain>

lib/spack/docs/workflows.rst

@@ -284,8 +284,10 @@ have some drawbacks:
    The ``spack load`` and ``spack module tcl loads`` commands, on the
    other hand, are not very smart: if the user-supplied spec matches
    more than one installed package, then ``spack module tcl loads`` will
-   fail. This may change in the future.  For now, the workaround is to
-   be more specific on any ``spack load`` commands that fail.
+   fail. This default behavior may change in the future.  For now, 
+   the workaround is to either be more specific on any failing ``spack load`` 
+   commands or to use ``spack load --first`` to allow spack to load the 
+   first matching spec.
 
 
 """"""""""""""""""""""

lib/spack/spack/cmd/__init__.py

@@ -177,7 +177,7 @@ def elide_list(line_list, max_num=10):
         return line_list
 
 
-def disambiguate_spec(spec, env, local=False, installed=True):
+def disambiguate_spec(spec, env, local=False, installed=True, first=False):
     """Given a spec, figure out which installed package it refers to.
 
     Arguments:
@@ -190,10 +190,11 @@ def disambiguate_spec(spec, env, local=False, installed=True):
             database query. See ``spack.database.Database._query`` for details.
     """
     hashes = env.all_hashes() if env else None
-    return disambiguate_spec_from_hashes(spec, hashes, local, installed)
+    return disambiguate_spec_from_hashes(spec, hashes, local, installed, first)
 
 
-def disambiguate_spec_from_hashes(spec, hashes, local=False, installed=True):
+def disambiguate_spec_from_hashes(spec, hashes, local=False,
+                                  installed=True, first=False):
     """Given a spec and a list of hashes, get concrete spec the spec refers to.
 
     Arguments:
@@ -213,6 +214,9 @@ def disambiguate_spec_from_hashes(spec, hashes, local=False, installed=True):
     if not matching_specs:
         tty.die("Spec '%s' matches no installed packages." % spec)
 
+    elif first:
+        return matching_specs[0]
+
     elif len(matching_specs) > 1:
         format_string = '{name}{@version}{%compiler}{arch=architecture}'
         args = ["%s matches multiple packages." % spec,

lib/spack/spack/cmd/load.py

@@ -33,6 +33,14 @@ def setup_parser(subparser):
         '--csh', action='store_const', dest='shell', const='csh',
         help="print csh commands to load the package")
 
+    subparser.add_argument(
+        '--first',
+        action='store_true',
+        default=False,
+        dest='load_first',
+        help="load the first match if multiple packages match the spec"
+    )
+
     subparser.add_argument(
         '--only',
         default='package,dependencies',
@@ -47,7 +55,7 @@ def setup_parser(subparser):
 
 def load(parser, args):
     env = ev.get_env(args, 'load')
-    specs = [spack.cmd.disambiguate_spec(spec, env)
+    specs = [spack.cmd.disambiguate_spec(spec, env, first=args.load_first)
              for spec in spack.cmd.parse_specs(args.specs)]
 
     if not args.shell:

lib/spack/spack/test/cmd/load.py

@@ -3,7 +3,8 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os
-from spack.main import SpackCommand
+import pytest
+from spack.main import SpackCommand, SpackCommandError
 import spack.spec
 import spack.user_environment as uenv
 
@@ -83,6 +84,18 @@ def test_load_includes_run_env(install_mockery, mock_fetch, mock_archive,
     assert 'setenv FOOBAR mpileaks' in csh_out
 
 
+def test_load_first(install_mockery, mock_fetch, mock_archive, mock_packages):
+    """Test with and without the --first option"""
+    install('libelf@0.8.12')
+    install('libelf@0.8.13')
+    # Now there are two versions of libelf
+    with pytest.raises(SpackCommandError):
+        # This should cause an error due to multiple versions
+        load('--sh', 'libelf')
+    # Using --first should avoid the error condition
+    load('--sh', '--first', 'libelf')
+
+
 def test_load_fails_no_shell(install_mockery, mock_fetch, mock_archive,
                              mock_packages):
     """Test that spack load prints an error message without a shell."""

share/spack/spack-completion.bash

@@ -984,7 +984,7 @@ _spack_list() {
 _spack_load() {
     if $list_options
     then
-        SPACK_COMPREPLY="-h --help -r --dependencies --sh --csh --only"
+        SPACK_COMPREPLY="-h --help -r --dependencies --sh --csh --first --only"
     else
         _installed_packages
     fi