Allow `spack install --overwrite` for nonexistent or multiple packages (#9201)

* Allow overwrite nonexistent and multiple packages

initial implementation
give one prompt to users instead of a prompt per spec
testing

* flake

* bugfix: install overwrite check each spec against installed

* python3 compliance for filter/map

2 files changed, 78 insertions, 25 deletions

diff --git a/lib/spack/spack/cmd/install.py b/lib/spack/spack/cmd/install.py
index fc79c5d689..5524324094 100644
--- a/lib/spack/spack/cmd/install.py
+++ b/lib/spack/spack/cmd/install.py
@@ -283,36 +283,42 @@ def install(parser, args, **kwargs):
     reporter.specs = specs
     with reporter:
         if args.overwrite:
-            # If we asked to overwrite an existing spec we must ensure that:
-            # 1. We have only one spec
-            # 2. The spec is already installed
-            assert len(specs) == 1, \
-                "only one spec is allowed when overwriting an installation"
-
-            spec = specs[0]
-            t = spack.store.db.query(spec)
-            assert len(t) == 1, "to overwrite a spec you must install it first"
-
-            # Give the user a last chance to think about overwriting an already
-            # existing installation
-            if not args.yes_to_all:
-                tty.msg('The following package will be reinstalled:\n')
 
+            installed = list(filter(lambda x: x,
+                                    map(spack.store.db.query_one, specs)))
+            if not args.yes_to_all:
                 display_args = {
                     'long': True,
                     'show_flags': True,
                     'variants': True
                 }
 
-                spack.cmd.display_specs(t, **display_args)
+                if installed:
+                    tty.msg('The following package specs will be '
+                            'reinstalled:\n')
+                    spack.cmd.display_specs(installed, **display_args)
+
+                not_installed = list(filter(lambda x: x not in installed,
+                                            specs))
+                if not_installed:
+                    tty.msg('The following package specs are not installed and'
+                            ' the --overwrite flag was given. The package spec'
+                            ' will be newly installed:\n')
+                    spack.cmd.display_specs(not_installed, **display_args)
+
+                # We have some specs, so one of the above must have been true
                 answer = tty.get_yes_or_no(
                     'Do you want to proceed?', default=False
                 )
                 if not answer:
                     tty.die('Reinstallation aborted.')
 
-            with fs.replace_directory_transaction(specs[0].prefix):
-                install_spec(args, kwargs, abstract_specs[0], specs[0])
+            for abstract, concrete in zip(abstract_specs, specs):
+                if concrete in installed:
+                    with fs.replace_directory_transaction(concrete.prefix):
+                        install_spec(args, kwargs, abstract, concrete)
+                else:
+                    install_spec(args, kwargs, abstract, concrete)
 
         else:
             for abstract, concrete in zip(abstract_specs, specs):
diff --git a/lib/spack/spack/test/cmd/install.py b/lib/spack/spack/test/cmd/install.py
index 12feba9555..f3e6a4d3ed 100644
--- a/lib/spack/spack/test/cmd/install.py
+++ b/lib/spack/spack/test/cmd/install.py
@@ -185,14 +185,6 @@ def test_show_log_on_error(mock_packages, mock_archive, mock_fetch,
 def test_install_overwrite(
         mock_packages, mock_archive, mock_fetch, config, install_mockery
 ):
-    # It's not possible to overwrite something that is not yet installed
-    with pytest.raises(AssertionError):
-        install('--overwrite', 'libdwarf')
-
-    # --overwrite requires a single spec
-    with pytest.raises(AssertionError):
-        install('--overwrite', 'libdwarf', 'libelf')
-
     # Try to install a spec and then to reinstall it.
     spec = Spec('libdwarf')
     spec.concretize()
@@ -217,6 +209,61 @@ def test_install_overwrite(
     assert fs.hash_directory(spec.prefix) != bad_md5
 
 
+def test_install_overwrite_not_installed(
+        mock_packages, mock_archive, mock_fetch, config, install_mockery
+):
+    # Try to install a spec and then to reinstall it.
+    spec = Spec('libdwarf')
+    spec.concretize()
+
+    assert not os.path.exists(spec.prefix)
+
+    install('--overwrite', '-y', 'libdwarf')
+    assert os.path.exists(spec.prefix)
+
+
+def test_install_overwrite_multiple(
+        mock_packages, mock_archive, mock_fetch, config, install_mockery
+):
+    # Try to install a spec and then to reinstall it.
+    libdwarf = Spec('libdwarf')
+    libdwarf.concretize()
+
+    install('libdwarf')
+
+    cmake = Spec('cmake')
+    cmake.concretize()
+
+    install('cmake')
+
+    assert os.path.exists(libdwarf.prefix)
+    expected_libdwarf_md5 = fs.hash_directory(libdwarf.prefix)
+
+    assert os.path.exists(cmake.prefix)
+    expected_cmake_md5 = fs.hash_directory(cmake.prefix)
+
+    # Modify the first installation to be sure the content is not the same
+    # as the one after we reinstalled
+    with open(os.path.join(libdwarf.prefix, 'only_in_old'), 'w') as f:
+        f.write('This content is here to differentiate installations.')
+    with open(os.path.join(cmake.prefix, 'only_in_old'), 'w') as f:
+        f.write('This content is here to differentiate installations.')
+
+    bad_libdwarf_md5 = fs.hash_directory(libdwarf.prefix)
+    bad_cmake_md5 = fs.hash_directory(cmake.prefix)
+
+    assert bad_libdwarf_md5 != expected_libdwarf_md5
+    assert bad_cmake_md5 != expected_cmake_md5
+
+    install('--overwrite', '-y', 'libdwarf', 'cmake')
+    assert os.path.exists(libdwarf.prefix)
+    assert os.path.exists(cmake.prefix)
+    assert fs.hash_directory(libdwarf.prefix) == expected_libdwarf_md5
+    assert fs.hash_directory(cmake.prefix) == expected_cmake_md5
+    assert fs.hash_directory(libdwarf.prefix) != bad_libdwarf_md5
+    assert fs.hash_directory(cmake.prefix) != bad_cmake_md5
+
+
 @pytest.mark.usefixtures(
     'mock_packages', 'mock_archive', 'mock_fetch', 'config', 'install_mockery',
 )