Auto merge of #12660 - epage:dry, r=weihanglo

feat(cli): Add '-n' to dry-run

This came from #12638 and my many small frustrations from wanting to use `-n` and not being able to.

We do not have any existing `-n` flags for this to be confused with.

I would wager that `-n` is such an entrenched short flag in build tools that it would not make sense for us to use it with any other flag.

For a survey of where `-n` is used as a short, see https://www.gnu.org/prep/standards/html_node/Option-Table.html#Option-Table

Author: bors

src/cargo/util/command_prelude.rs

@@ -302,7 +302,7 @@ pub trait CommandExt: Sized {
     }
 
     fn arg_dry_run(self, dry_run: &'static str) -> Self {
-        self._arg(flag("dry-run", dry_run))
+        self._arg(flag("dry-run", dry_run).short('n'))
     }
 
     fn arg_ignore_rust_version(self) -> Self {

tests/testsuite/cargo_add/help/stdout.log

@@ -42,7 +42,7 @@ Options:
       --ignore-rust-version
           Ignore `rust-version` specification in packages (unstable)
 
-      --dry-run
+  -n, --dry-run
           Don't actually write the manifest
 
   -q, --quiet

tests/testsuite/cargo_publish/help/stdout.log

@@ -3,7 +3,7 @@ Upload a package to the registry
 Usage: cargo[EXE] publish [OPTIONS]
 
 Options:
-      --dry-run              Perform all checks without uploading
+  -n, --dry-run              Perform all checks without uploading
       --index <INDEX>        Registry index URL to upload the package to
       --registry <REGISTRY>  Registry to upload the package to
       --token <TOKEN>        Token to use when uploading

tests/testsuite/cargo_remove/help/stdout.log

@@ -6,7 +6,7 @@ Arguments:
   <DEP_ID>...  Dependencies to be removed
 
 Options:
-      --dry-run             Don't actually write the manifest
+  -n, --dry-run             Don't actually write the manifest
   -q, --quiet               Do not print cargo log messages
   -v, --verbose...          Use verbose output (-vv very verbose/build.rs output)
       --color <WHEN>        Coloring: auto, always, never

tests/testsuite/cargo_update/help/stdout.log

@@ -3,7 +3,7 @@ Update dependencies as recorded in the local lock file
 Usage: cargo[EXE] update [OPTIONS] [SPEC]...
 
 Options:
-      --dry-run             Don't actually write the lockfile
+  -n, --dry-run             Don't actually write the lockfile
       --recursive           Force updating all dependencies of [SPEC]... as well
       --precise <PRECISE>   Update [SPEC] to exactly PRECISE
   -q, --quiet               Do not print cargo log messages