Merge branch 'jc/sha1-name-more'

Teaches the object name parser things like a "git describe" output
is always a commit object, "A" in "git log A" must be a committish,
and "A" and "B" in "git log A...B" both must be committish, etc., to
prolong the lifetime of abbreviated object names.

* jc/sha1-name-more: (27 commits)
  t1512: match the "other" object names
  t1512: ignore whitespaces in wc -l output
  rev-parse --disambiguate=<prefix>
  rev-parse: A and B in "rev-parse A..B" refer to committish
  reset: the command takes committish
  commit-tree: the command wants a tree and commits
  apply: --build-fake-ancestor expects blobs
  sha1_name.c: add support for disambiguating other types
  revision.c: the "log" family, except for "show", takes committish
  revision.c: allow handle_revision_arg() to take other flags
  sha1_name.c: introduce get_sha1_committish()
  sha1_name.c: teach lookup context to get_sha1_with_context()
  sha1_name.c: many short names can only be committish
  sha1_name.c: get_sha1_1() takes lookup flags
  sha1_name.c: get_describe_name() by definition groks only commits
  sha1_name.c: teach get_short_sha1() a commit-only option
  sha1_name.c: allow get_short_sha1() to take other flags
  get_sha1(): fix error status regression
  sha1_name.c: restructure disambiguation of short names
  sha1_name.c: correct misnamed "canonical" and "res"
  ...

1 files changed, 264 insertions, 0 deletions

diff --git a/t/t1512-rev-parse-disambiguation.sh b/t/t1512-rev-parse-disambiguation.sh
new file mode 100755
index 0000000000..6b3d797cea
--- /dev/null
+++ b/t/t1512-rev-parse-disambiguation.sh
@@ -0,0 +1,264 @@
+#!/bin/sh
+
+test_description='object name disambiguation
+
+Create blobs, trees, commits and a tag that all share the same
+prefix, and make sure "git rev-parse" can take advantage of
+type information to disambiguate short object names that are
+not necessarily unique.
+
+The final history used in the test has five commits, with the bottom
+one tagged as v1.0.0.  They all have one regular file each.
+
+  +-------------------------------------------+
+  |                                           |
+  |           .-------b3wettvi---- ad2uee     |
+  |          /                   /            |
+  |  a2onsxbvj---czy8f73t--ioiley5o           |
+  |                                           |
+  +-------------------------------------------+
+
+'
+
+. ./test-lib.sh
+
+test_expect_success 'blob and tree' '
+	test_tick &&
+	(
+		for i in 0 1 2 3 4 5 6 7 8 9
+		do
+			echo $i
+		done
+		echo
+		echo b1rwzyc3
+	) >a0blgqsjc &&
+
+	# create one blob 0000000000b36
+	git add a0blgqsjc &&
+
+	# create one tree 0000000000cdc
+	git write-tree
+'
+
+test_expect_success 'warn ambiguity when no candidate matches type hint' '
+	test_must_fail git rev-parse --verify 000000000^{commit} 2>actual &&
+	grep "short SHA1 000000000 is ambiguous" actual
+'
+
+test_expect_success 'disambiguate tree-ish' '
+	# feed tree-ish in an unambiguous way
+	git rev-parse --verify 0000000000cdc:a0blgqsjc &&
+
+	# ambiguous at the object name level, but there is only one
+	# such tree-ish (the other is a blob)
+	git rev-parse --verify 000000000:a0blgqsjc
+'
+
+test_expect_success 'disambiguate blob' '
+	sed -e "s/|$//" >patch <<-EOF &&
+	diff --git a/frotz b/frotz
+	index 000000000..ffffff 100644
+	--- a/frotz
+	+++ b/frotz
+	@@ -10,3 +10,4 @@
+	 9
+	 |
+	 b1rwzyc3
+	+irwry
+	EOF
+	(
+		GIT_INDEX_FILE=frotz &&
+		export GIT_INDEX_FILE &&
+		git apply --build-fake-ancestor frotz patch &&
+		git cat-file blob :frotz >actual
+	) &&
+	test_cmp a0blgqsjc actual
+'
+
+test_expect_success 'disambiguate tree' '
+	commit=$(echo "d7xm" | git commit-tree 000000000) &&
+	test $(git rev-parse $commit^{tree}) = $(git rev-parse 0000000000cdc)
+'
+
+test_expect_success 'first commit' '
+	# create one commit 0000000000e4f
+	git commit -m a2onsxbvj
+'
+
+test_expect_success 'disambiguate commit-ish' '
+	# feed commit-ish in an unambiguous way
+	git rev-parse --verify 0000000000e4f^{commit} &&
+
+	# ambiguous at the object name level, but there is only one
+	# such commit (the others are tree and blob)
+	git rev-parse --verify 000000000^{commit} &&
+
+	# likewise
+	git rev-parse --verify 000000000^0
+'
+
+test_expect_success 'disambiguate commit' '
+	commit=$(echo "hoaxj" | git commit-tree 0000000000cdc -p 000000000) &&
+	test $(git rev-parse $commit^) = $(git rev-parse 0000000000e4f)
+'
+
+test_expect_success 'log name1..name2 takes only commit-ishes on both ends' '
+	git log 000000000..000000000 &&
+	git log ..000000000 &&
+	git log 000000000.. &&
+	git log 000000000...000000000 &&
+	git log ...000000000 &&
+	git log 000000000...
+'
+
+test_expect_success 'rev-parse name1..name2 takes only commit-ishes on both ends' '
+	git rev-parse 000000000..000000000 &&
+	git rev-parse ..000000000 &&
+	git rev-parse 000000000..
+'
+
+test_expect_success 'git log takes only commit-ish' '
+	git log 000000000
+'
+
+test_expect_success 'git reset takes only commit-ish' '
+	git reset 000000000
+'
+
+test_expect_success 'first tag' '
+	# create one tag 0000000000f8f
+	git tag -a -m j7cp83um v1.0.0
+'
+
+test_expect_failure 'two semi-ambiguous commit-ish' '
+	# Once the parser becomes ultra-smart, it could notice that
+	# 110282 before ^{commit} name many different objects, but
+	# that only two (HEAD and v1.0.0 tag) can be peeled to commit,
+	# and that peeling them down to commit yield the same commit
+	# without ambiguity.
+	git rev-parse --verify 110282^{commit} &&
+
+	# likewise
+	git log 000000000..000000000 &&
+	git log ..000000000 &&
+	git log 000000000.. &&
+	git log 000000000...000000000 &&
+	git log ...000000000 &&
+	git log 000000000...
+'
+
+test_expect_failure 'three semi-ambiguous tree-ish' '
+	# Likewise for tree-ish.  HEAD, v1.0.0 and HEAD^{tree} share
+	# the prefix but peeling them to tree yields the same thing
+	git rev-parse --verify 000000000^{tree}
+'
+
+test_expect_success 'parse describe name' '
+	# feed an unambiguous describe name
+	git rev-parse --verify v1.0.0-0-g0000000000e4f &&
+
+	# ambiguous at the object name level, but there is only one
+	# such commit (others are blob, tree and tag)
+	git rev-parse --verify v1.0.0-0-g000000000
+'
+
+test_expect_success 'more history' '
+	# commit 0000000000043
+	git mv a0blgqsjc d12cr3h8t &&
+	echo h62xsjeu >>d12cr3h8t &&
+	git add d12cr3h8t &&
+
+	test_tick &&
+	git commit -m czy8f73t &&
+
+	# commit 00000000008ec
+	git mv d12cr3h8t j000jmpzn &&
+	echo j08bekfvt >>j000jmpzn &&
+	git add j000jmpzn &&
+
+	test_tick &&
+	git commit -m ioiley5o &&
+
+	# commit 0000000005b0
+	git checkout v1.0.0^0 &&
+	git mv a0blgqsjc f5518nwu &&
+
+	for i in h62xsjeu j08bekfvt kg7xflhm
+	do
+		echo $i
+	done >>f5518nwu &&
+	git add f5518nwu &&
+
+	test_tick &&
+	git commit -m b3wettvi &&
+	side=$(git rev-parse HEAD) &&
+
+	# commit 000000000066
+	git checkout master &&
+
+	# If you use recursive, merge will fail and you will need to
+	# clean up a0blgqsjc as well.  If you use resolve, merge will
+	# succeed.
+	test_might_fail git merge --no-commit -s recursive $side &&
+	git rm -f f5518nwu j000jmpzn &&
+
+	test_might_fail git rm -f a0blgqsjc &&
+	(
+		git cat-file blob $side:f5518nwu
+		echo j3l0i9s6
+	) >ab2gs879 &&
+	git add ab2gs879 &&
+
+	test_tick &&
+	git commit -m ad2uee
+
+'
+
+test_expect_failure 'parse describe name taking advantage of generation' '
+	# ambiguous at the object name level, but there is only one
+	# such commit at generation 0
+	git rev-parse --verify v1.0.0-0-g000000000 &&
+
+	# likewise for generation 2 and 4
+	git rev-parse --verify v1.0.0-2-g000000000 &&
+	git rev-parse --verify v1.0.0-4-g000000000
+'
+
+# Note: because rev-parse does not even try to disambiguate based on
+# the generation number, this test currently succeeds for a wrong
+# reason.  When it learns to use the generation number, the previous
+# test should succeed, and also this test should fail because the
+# describe name used in the test with generation number can name two
+# commits.  Make sure that such a future enhancement does not randomly
+# pick one.
+test_expect_success 'parse describe name not ignoring ambiguity' '
+	# ambiguous at the object name level, and there are two such
+	# commits at generation 1
+	test_must_fail git rev-parse --verify v1.0.0-1-g000000000
+'
+
+test_expect_success 'ambiguous commit-ish' '
+	# Now there are many commits that begin with the
+	# common prefix, none of these should pick one at
+	# random.  They all should result in ambiguity errors.
+	test_must_fail git rev-parse --verify 110282^{commit} &&
+
+	# likewise
+	test_must_fail git log 000000000..000000000 &&
+	test_must_fail git log ..000000000 &&
+	test_must_fail git log 000000000.. &&
+	test_must_fail git log 000000000...000000000 &&
+	test_must_fail git log ...000000000 &&
+	test_must_fail git log 000000000...
+'
+
+test_expect_success 'rev-parse --disambiguate' '
+	# The test creates 16 objects that share the prefix and two
+	# commits created by commit-tree in earlier tests share a
+	# different prefix.
+	git rev-parse --disambiguate=000000000 >actual &&
+	test $(wc -l <actual) = 16 &&
+	test "$(sed -e "s/^\(.........\).*/\1/" actual | sort -u)" = 000000000
+'
+
+test_done