Add command and package suggestions (#40895)

* Add command suggestions

This adds suggestions of similar commands in case users mistype a
command. Before:
```
$ spack spack
==> Error: spack is not a recognized Spack command or extension command; check with `spack commands`.
```
After:
```
$ spack spack
==> Error: spack is not a recognized Spack command or extension command; check with `spack commands`.

Did you mean one of the following commands?
  spec
  patch
```

* Add package name suggestions

* Remove suggestion to run spack clean -m

lib/spack/spack/cmd/dev_build.py

@@ -99,10 +99,7 @@ def dev_build(self, args):
 
     spec = specs[0]
     if not spack.repo.PATH.exists(spec.name):
-        tty.die(
+        raise spack.repo.UnknownPackageError(spec.name)
-            "No package for '{0}' was found.".format(spec.name),
-            "  Use `spack create` to create a new package",
-        )
 
     if not spec.versions.concrete_range_as_version:
         tty.die(

lib/spack/spack/cmd/edit.py

@@ -43,10 +43,7 @@ def edit_package(name, repo_path, namespace):
         if not os.access(path, os.R_OK):
             tty.die("Insufficient permissions on '%s'!" % path)
     else:
-        tty.die(
+        raise spack.repo.UnknownPackageError(spec.name)
-            "No package for '{0}' was found.".format(spec.name),
-            "  Use `spack create` to create a new package",
-        )
 
     editor(path)
 

lib/spack/spack/extensions.py

@@ -5,6 +5,7 @@
 """Service functions and classes to implement the hooks
 for Spack's command extensions.
 """
+import difflib
 import importlib
 import os
 import re
@@ -176,10 +177,19 @@ class CommandNotFoundError(spack.error.SpackError):
     """
 
     def __init__(self, cmd_name):
-        super().__init__(
+        msg = (
             "{0} is not a recognized Spack command or extension command;"
             " check with `spack commands`.".format(cmd_name)
         )
+        long_msg = None
+
+        similar = difflib.get_close_matches(cmd_name, spack.cmd.all_commands())
+
+        if 1 <= len(similar) <= 5:
+            long_msg = "\nDid you mean one of the following commands?\n  "
+            long_msg += "\n  ".join(similar)
+
+        super().__init__(msg, long_msg)
 
 
 class ExtensionNamingError(spack.error.SpackError):

lib/spack/spack/repo.py

@@ -6,6 +6,7 @@
 import abc
 import collections.abc
 import contextlib
+import difflib
 import errno
 import functools
 import importlib
@@ -1516,7 +1517,18 @@ def __init__(self, name, repo=None):
                 long_msg = "Did you mean to specify a filename with './{0}'?"
                 long_msg = long_msg.format(name)
             else:
-                long_msg = "You may need to run 'spack clean -m'."
+                long_msg = "Use 'spack create' to create a new package."
+
+                if not repo:
+                    repo = spack.repo.PATH
+
+                # We need to compare the base package name
+                pkg_name = name.rsplit(".", 1)[-1]
+                similar = difflib.get_close_matches(pkg_name, repo.all_package_names())
+
+                if 1 <= len(similar) <= 5:
+                    long_msg += "\n\nDid you mean one of the following packages?\n  "
+                    long_msg += "\n  ".join(similar)
 
         super().__init__(msg, long_msg)
         self.name = name

lib/spack/spack/test/cmd/dev_build.py

@@ -163,8 +163,15 @@ def test_dev_build_fails_multiple_specs(mock_packages):
 
 
 def test_dev_build_fails_nonexistent_package_name(mock_packages):
-    output = dev_build("no_such_package", fail_on_error=False)
+    output = ""
-    assert "No package for 'no_such_package' was found" in output
+
+    try:
+        dev_build("no_such_package")
+        assert False, "no exception was raised!"
+    except spack.repo.UnknownPackageError as e:
+        output = e.message
+
+    assert "Package 'no_such_package' not found" in output
 
 
 def test_dev_build_fails_no_version(mock_packages):