merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/t/t1508-at-combinations.sh

@@ -0,0 +1,102 @@
+#!/bin/sh
+
+test_description='test various @{X} syntax combinations together'
+. ./test-lib.sh
+
+check() {
+	test_expect_${4:-success} "$1 = $3" "
+		echo '$3' >expect &&
+		if test '$2' = 'commit'
+		then
+			git log -1 --format=%s '$1' >actual
+		elif test '$2' = 'ref'
+		then
+			git rev-parse --symbolic-full-name '$1' >actual
+		else
+			git cat-file -p '$1' >actual
+		fi &&
+		test_cmp expect actual
+	"
+}
+
+nonsense() {
+	test_expect_${2:-success} "$1 is nonsensical" "
+		test_must_fail git rev-parse --verify '$1'
+	"
+}
+
+fail() {
+	"$@" failure
+}
+
+test_expect_success 'setup' '
+	test_commit master-one &&
+	test_commit master-two &&
+	git checkout -b upstream-branch &&
+	test_commit upstream-one &&
+	test_commit upstream-two &&
+	if test_have_prereq !MINGW
+	then
+		git checkout -b @/at-test
+	fi &&
+	git checkout -b @@/at-test &&
+	git checkout -b @at-test &&
+	git checkout -b old-branch &&
+	test_commit old-one &&
+	test_commit old-two &&
+	git checkout -b new-branch &&
+	test_commit new-one &&
+	test_commit new-two &&
+	git branch -u master old-branch &&
+	git branch -u upstream-branch new-branch
+'
+
+check HEAD ref refs/heads/new-branch
+check "@{1}" commit new-one
+check "HEAD@{1}" commit new-one
+check "@{now}" commit new-two
+check "HEAD@{now}" commit new-two
+check "@{-1}" ref refs/heads/old-branch
+check "@{-1}@{0}" commit old-two
+check "@{-1}@{1}" commit old-one
+check "@{u}" ref refs/heads/upstream-branch
+check "HEAD@{u}" ref refs/heads/upstream-branch
+check "@{u}@{1}" commit upstream-one
+check "@{-1}@{u}" ref refs/heads/master
+check "@{-1}@{u}@{1}" commit master-one
+check "@" commit new-two
+check "@@{u}" ref refs/heads/upstream-branch
+check "@@/at-test" ref refs/heads/@@/at-test
+test_have_prereq MINGW ||
+check "@/at-test" ref refs/heads/@/at-test
+check "@at-test" ref refs/heads/@at-test
+nonsense "@{u}@{-1}"
+nonsense "@{0}@{0}"
+nonsense "@{1}@{u}"
+nonsense "HEAD@{-1}"
+nonsense "@{-1}@{-1}"
+
+# @{N} versus HEAD@{N}
+
+check "HEAD@{3}" commit old-two
+nonsense "@{3}"
+
+test_expect_success 'switch to old-branch' '
+	git checkout old-branch
+'
+
+check HEAD ref refs/heads/old-branch
+check "HEAD@{1}" commit new-two
+check "@{1}" commit old-one
+
+test_expect_success 'create path with @' '
+	echo content >normal &&
+	echo content >fun@ny &&
+	git add normal fun@ny &&
+	git commit -m "funny path"
+'
+
+check "@:normal" blob content
+check "@:fun@ny" blob content
+
+test_done