checkout, restore: support the --pathspec-from-file option

Decisions taken for simplicity:
1) For now, `--pathspec-from-file` is declared incompatible with
   `--patch`, even when <file> is not `stdin`. Such use case it not
   really expected.
2) It is not allowed to pass pathspec in both args and file.

`you must specify path(s) to restore` block was moved down to be able to
test for `pathspec.nr` instead, because testing for `argc` is no longer
correct.

`git switch` does not support the new options because it doesn't expect
`<pathspec>` arguments.

Signed-off-by: Alexandr Miloslavskiy <alexandr.miloslavskiy@syntevo.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t2072-restore-pathspec-file.sh

@@ -0,0 +1,139 @@
+#!/bin/sh
+
+test_description='restore --pathspec-from-file'
+
+. ./test-lib.sh
+
+test_tick
+
+test_expect_success setup '
+	test_commit file0 &&
+
+	echo 1 >fileA.t &&
+	echo 1 >fileB.t &&
+	echo 1 >fileC.t &&
+	echo 1 >fileD.t &&
+	git add fileA.t fileB.t fileC.t fileD.t &&
+	git commit -m "files 1" &&
+
+	echo 2 >fileA.t &&
+	echo 2 >fileB.t &&
+	echo 2 >fileC.t &&
+	echo 2 >fileD.t &&
+	git add fileA.t fileB.t fileC.t fileD.t &&
+	git commit -m "files 2" &&
+
+	git tag checkpoint
+'
+
+restore_checkpoint () {
+	git reset --hard checkpoint
+}
+
+verify_expect () {
+	git status --porcelain --untracked-files=no -- fileA.t fileB.t fileC.t fileD.t >actual &&
+	test_cmp expect actual
+}
+
+test_expect_success '--pathspec-from-file from stdin' '
+	restore_checkpoint &&
+
+	echo fileA.t | git restore --pathspec-from-file=- --source=HEAD^1 &&
+
+	cat >expect <<-\EOF &&
+	 M fileA.t
+	EOF
+	verify_expect
+'
+
+test_expect_success '--pathspec-from-file from file' '
+	restore_checkpoint &&
+
+	echo fileA.t >list &&
+	git restore --pathspec-from-file=list --source=HEAD^1 &&
+
+	cat >expect <<-\EOF &&
+	 M fileA.t
+	EOF
+	verify_expect
+'
+
+test_expect_success 'NUL delimiters' '
+	restore_checkpoint &&
+
+	printf "fileA.t\0fileB.t\0" | git restore --pathspec-from-file=- --pathspec-file-nul --source=HEAD^1 &&
+
+	cat >expect <<-\EOF &&
+	 M fileA.t
+	 M fileB.t
+	EOF
+	verify_expect
+'
+
+test_expect_success 'LF delimiters' '
+	restore_checkpoint &&
+
+	printf "fileA.t\nfileB.t\n" | git restore --pathspec-from-file=- --source=HEAD^1 &&
+
+	cat >expect <<-\EOF &&
+	 M fileA.t
+	 M fileB.t
+	EOF
+	verify_expect
+'
+
+test_expect_success 'no trailing delimiter' '
+	restore_checkpoint &&
+
+	printf "fileA.t\nfileB.t" | git restore --pathspec-from-file=- --source=HEAD^1 &&
+
+	cat >expect <<-\EOF &&
+	 M fileA.t
+	 M fileB.t
+	EOF
+	verify_expect
+'
+
+test_expect_success 'CRLF delimiters' '
+	restore_checkpoint &&
+
+	printf "fileA.t\r\nfileB.t\r\n" | git restore --pathspec-from-file=- --source=HEAD^1 &&
+
+	cat >expect <<-\EOF &&
+	 M fileA.t
+	 M fileB.t
+	EOF
+	verify_expect
+'
+
+test_expect_success 'quotes' '
+	restore_checkpoint &&
+
+	printf "\"file\\101.t\"" | git restore --pathspec-from-file=- --source=HEAD^1 &&
+
+	cat >expect <<-\EOF &&
+	 M fileA.t
+	EOF
+	verify_expect
+'
+
+test_expect_success 'quotes not compatible with --pathspec-file-nul' '
+	restore_checkpoint &&
+
+	printf "\"file\\101.t\"" >list &&
+	test_must_fail git restore --pathspec-from-file=list --pathspec-file-nul --source=HEAD^1
+'
+
+test_expect_success 'only touches what was listed' '
+	restore_checkpoint &&
+
+	printf "fileB.t\nfileC.t\n" | git restore --pathspec-from-file=- --source=HEAD^1 &&
+
+	cat >expect <<-\EOF &&
+	 M fileB.t
+	 M fileC.t
+	EOF
+	verify_expect
+'
+
+test_done