Add shell completion for shorthand commands

Currently `cargo` has shell completion for most (if not all) builtin
commands such as `build`, `run`, `check` etc.
However, it doesn't have shell completion for the short forms of these
commands, such as `b`, `r`, `c` etc.

This commit adds both bash and zsh completions for command shorthands.

Fixes #9086.

src/etc/_cargo

@@ -77,7 +77,7 @@ _cargo() {
                         '*:args:_default'
                         ;;
 
-                build)
+                build | b)
                     _arguments -s -S $common $parallel $features $msgfmt $triple $target $manifest \
                         '--all-targets[equivalent to specifying --lib --bins --tests --benches --examples]' \
                         "${command_scope_spec[@]}" \
@@ -86,7 +86,7 @@ _cargo() {
                         '--build-plan[output the build plan in JSON]' \
                         ;;
 
-                check)
+                check | c)
                     _arguments -s -S $common $parallel $features $msgfmt $triple $target $manifest \
                         '--all-targets[equivalent to specifying --lib --bins --tests --benches --examples]' \
                         "${command_scope_spec[@]}" \
@@ -101,7 +101,7 @@ _cargo() {
                         '--doc[clean just the documentation directory]'
                         ;;
 
-                doc)
+                doc | d)
                     _arguments -s -S $common $parallel $features $msgfmt $triple $target $manifest \
                         '--no-deps[do not build docs for dependencies]' \
                         '--document-private-items[include non-public items in the documentation]' \
@@ -220,7 +220,7 @@ _cargo() {
                     _arguments -s -S $common $manifest
                         ;;
 
-                run)
+                run | r)
                     _arguments -s -S $common $parallel $features $msgfmt $triple $target $manifest \
                         '--example=[name of the bin target]:name:_cargo_example_names' \
                         '--bin=[name of the bin target]:name' \
@@ -255,7 +255,7 @@ _cargo() {
                         '*: :_guard "^-*" "query"'
                         ;;
 
-                test)
+                test | t)
                     _arguments -s -S $common $parallel $features $msgfmt $triple $target $manifest \
                         '--test=[test name]: :_cargo_test_names' \
                         '--no-fail-fast[run all tests regardless of failure]' \

src/etc/cargo.bashcomp.sh

@@ -50,9 +50,12 @@ _cargo()
 	local opt___nocmd="$opt_common -V --version --list --explain"
 	local opt__bench="$opt_common $opt_pkg_spec $opt_feat $opt_mani $opt_lock $opt_jobs $opt_targets --message-format --target --no-run --no-fail-fast --target-dir"
 	local opt__build="$opt_common $opt_pkg_spec $opt_feat $opt_mani $opt_lock $opt_jobs $opt_targets --message-format --target --release --profile --target-dir"
+	local opt__b="$opt__build"
 	local opt__check="$opt_common $opt_pkg_spec $opt_feat $opt_mani $opt_lock $opt_jobs $opt_targets --message-format --target --release --profile --target-dir"
+	local opt__c="$opt__check"
 	local opt__clean="$opt_common $opt_pkg $opt_mani $opt_lock --target --release --doc --target-dir --profile"
 	local opt__doc="$opt_common $opt_pkg_spec $opt_feat $opt_mani $opt_lock $opt_jobs --message-format --bin --bins --lib --target --open --no-deps --release --document-private-items --target-dir --profile"
+	local opt__d="$opt__doc"
 	local opt__fetch="$opt_common $opt_mani $opt_lock --target"
 	local opt__fix="$opt_common $opt_pkg_spec $opt_feat $opt_mani $opt_jobs $opt_targets $opt_lock --release --target --message-format --broken-code --edition --edition-idioms --allow-no-vcs --allow-dirty --allow-staged --profile --target-dir"
 	local opt__generate_lockfile="$opt_common $opt_mani $opt_lock"
@@ -69,10 +72,12 @@ _cargo()
 	local opt__publish="$opt_common $opt_mani $opt_feat $opt_lock $opt_jobs --allow-dirty --dry-run --token --no-verify --index --registry --target --target-dir"
 	local opt__read_manifest="$opt_help $opt_quiet $opt_verbose $opt_mani $opt_color $opt_lock --no-deps"
 	local opt__run="$opt_common $opt_pkg $opt_feat $opt_mani $opt_lock $opt_jobs --message-format --target --bin --example --release --target-dir --profile"
+	local opt__r="$opt__run"
 	local opt__rustc="$opt_common $opt_pkg $opt_feat $opt_mani $opt_lock $opt_jobs $opt_targets -L --crate-type --extern --message-format --profile --target --release --target-dir"
 	local opt__rustdoc="$opt_common $opt_pkg $opt_feat $opt_mani $opt_lock $opt_jobs $opt_targets --message-format --target --release --open --target-dir --profile"
 	local opt__search="$opt_common $opt_lock --limit --index --registry"
 	local opt__test="$opt_common $opt_pkg_spec $opt_feat $opt_mani $opt_lock $opt_jobs $opt_targets --message-format --doc --target --no-run --release --no-fail-fast --target-dir --profile"
+	local opt__t="$opt__test"
 	local opt__tree="$opt_common $opt_pkg_spec $opt_feat $opt_mani $opt_lock --target -i --invert --prefix --no-dedupe --duplicates -d --charset -f --format -e --edges"
 	local opt__uninstall="$opt_common $opt_lock $opt_pkg --bin --root"
 	local opt__update="$opt_common $opt_mani $opt_lock $opt_pkg --aggressive --precise --dry-run"