Merge branch 'nd/cache-tree-ita' into maint

"git add -N dir/file && git write-tree" produced an incorrect tree
when there are other paths in the same directory that sorts after
"file".

* nd/cache-tree-ita:
  cache-tree: do not generate empty trees as a result of all i-t-a subentries
  cache-tree.c: fix i-t-a entry skipping directory updates sometimes
  test-lib.sh: introduce and use $EMPTY_BLOB
  test-lib.sh: introduce and use $EMPTY_TREE

14 files changed, 76 insertions, 50 deletions

diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 60811a3a7c..1aa5093f36 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -834,7 +834,7 @@ test_expect_success 'git write-tree should be able to write an empty tree' '
 '
 
 test_expect_success 'validate object ID of a known tree' '
-	test "$tree" = 4b825dc642cb6eb9a060e54bf8d69288fbee4904
+	test "$tree" = $EMPTY_TREE
 '
 
 # Various types of objects
diff --git a/t/t1011-read-tree-sparse-checkout.sh b/t/t1011-read-tree-sparse-checkout.sh
index 0c74beedd2..2563d18440 100755
--- a/t/t1011-read-tree-sparse-checkout.sh
+++ b/t/t1011-read-tree-sparse-checkout.sh
@@ -15,11 +15,11 @@ test_description='sparse checkout tests
 . "$TEST_DIRECTORY"/lib-read-tree.sh
 
 test_expect_success 'setup' '
-	cat >expected <<-\EOF &&
+	cat >expected <<-EOF &&
 	100644 77f0ba1734ed79d12881f81b36ee134de6a3327b 0	init.t
-	100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	sub/added
-	100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	sub/addedtoo
-	100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	subsub/added
+	100644 $EMPTY_BLOB 0	sub/added
+	100644 $EMPTY_BLOB 0	sub/addedtoo
+	100644 $EMPTY_BLOB 0	subsub/added
 	EOF
 	cat >expected.swt <<-\EOF &&
 	H init.t
diff --git a/t/t1100-commit-tree-options.sh b/t/t1100-commit-tree-options.sh
index b7e9b4fc5b..ae66ba5bab 100755
--- a/t/t1100-commit-tree-options.sh
+++ b/t/t1100-commit-tree-options.sh
@@ -15,7 +15,7 @@ Also make sure that command line parser understands the normal
 . ./test-lib.sh
 
 cat >expected <<EOF
-tree 4b825dc642cb6eb9a060e54bf8d69288fbee4904
+tree $EMPTY_TREE
 author Author Name <author@email> 1117148400 +0000
 committer Committer Name <committer@email> 1117150200 +0000
 
diff --git a/t/t1700-split-index.sh b/t/t1700-split-index.sh
index 8aef49f236..292a0720fc 100755
--- a/t/t1700-split-index.sh
+++ b/t/t1700-split-index.sh
@@ -33,14 +33,14 @@ test_expect_success 'add one file' '
 	git update-index --add one &&
 	git ls-files --stage >ls-files.actual &&
 	cat >ls-files.expect <<EOF &&
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	one
+100644 $EMPTY_BLOB 0	one
 EOF
 	test_cmp ls-files.expect ls-files.actual &&
 
 	test-dump-split-index .git/index | sed "/^own/d" >actual &&
 	cat >expect <<EOF &&
 base $base
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	one
+100644 $EMPTY_BLOB 0	one
 replacements:
 deletions:
 EOF
@@ -51,7 +51,7 @@ test_expect_success 'disable split index' '
 	git update-index --no-split-index &&
 	git ls-files --stage >ls-files.actual &&
 	cat >ls-files.expect <<EOF &&
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	one
+100644 $EMPTY_BLOB 0	one
 EOF
 	test_cmp ls-files.expect ls-files.actual &&
 
@@ -67,7 +67,7 @@ test_expect_success 'enable split index again, "one" now belongs to base index"'
 	git update-index --split-index &&
 	git ls-files --stage >ls-files.actual &&
 	cat >ls-files.expect <<EOF &&
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	one
+100644 $EMPTY_BLOB 0	one
 EOF
 	test_cmp ls-files.expect ls-files.actual &&
 
@@ -105,7 +105,7 @@ test_expect_success 'add another file, which stays index' '
 	git ls-files --stage >ls-files.actual &&
 	cat >ls-files.expect <<EOF &&
 100644 2e0996000b7e9019eabcad29391bf0f5c7702f0b 0	one
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	two
+100644 $EMPTY_BLOB 0	two
 EOF
 	test_cmp ls-files.expect ls-files.actual &&
 
@@ -113,7 +113,7 @@ EOF
 	q_to_tab >expect <<EOF &&
 $BASE
 100644 2e0996000b7e9019eabcad29391bf0f5c7702f0b 0Q
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	two
+100644 $EMPTY_BLOB 0	two
 replacements: 0
 deletions:
 EOF
@@ -159,14 +159,14 @@ test_expect_success 'add original file back' '
 	git update-index --add one &&
 	git ls-files --stage >ls-files.actual &&
 	cat >ls-files.expect <<EOF &&
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	one
+100644 $EMPTY_BLOB 0	one
 EOF
 	test_cmp ls-files.expect ls-files.actual &&
 
 	test-dump-split-index .git/index | sed "/^own/d" >actual &&
 	cat >expect <<EOF &&
 $BASE
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	one
+100644 $EMPTY_BLOB 0	one
 replacements:
 deletions: 0
 EOF
@@ -178,8 +178,8 @@ test_expect_success 'add new file' '
 	git update-index --add two &&
 	git ls-files --stage >actual &&
 	cat >expect <<EOF &&
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	one
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	two
+100644 $EMPTY_BLOB 0	one
+100644 $EMPTY_BLOB 0	two
 EOF
 	test_cmp expect actual
 '
@@ -188,8 +188,8 @@ test_expect_success 'unify index, two files remain' '
 	git update-index --no-split-index &&
 	git ls-files --stage >ls-files.actual &&
 	cat >ls-files.expect <<EOF &&
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	one
-100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0	two
+100644 $EMPTY_BLOB 0	one
+100644 $EMPTY_BLOB 0	two
 EOF
 	test_cmp ls-files.expect ls-files.actual &&
 
diff --git a/t/t2203-add-intent.sh b/t/t2203-add-intent.sh
index 2a4a749b4f..8f22c43e24 100755
--- a/t/t2203-add-intent.sh
+++ b/t/t2203-add-intent.sh
@@ -82,5 +82,36 @@ test_expect_success 'cache-tree invalidates i-t-a paths' '
 	test_cmp expect actual
 '
 
+test_expect_success 'cache-tree does not ignore dir that has i-t-a entries' '
+	git init ita-in-dir &&
+	(
+		cd ita-in-dir &&
+		mkdir 2 &&
+		for f in 1 2/1 2/2 3
+		do
+			echo "$f" >"$f"
+		done &&
+		git add 1 2/2 3 &&
+		git add -N 2/1 &&
+		git commit -m committed &&
+		git ls-tree -r HEAD >actual &&
+		grep 2/2 actual
+	)
+'
+
+test_expect_success 'cache-tree does skip dir that becomes empty' '
+	rm -fr ita-in-dir &&
+	git init ita-in-dir &&
+	(
+		cd ita-in-dir &&
+		mkdir -p 1/2/3 &&
+		echo 4 >1/2/3/4 &&
+		git add -N 1/2/3/4 &&
+		git write-tree >actual &&
+		echo $EMPTY_TREE >expected &&
+		test_cmp expected actual
+	)
+'
+
 test_done
 
diff --git a/t/t3102-ls-tree-wildcards.sh b/t/t3102-ls-tree-wildcards.sh
index 4d4b02e760..e804377f1c 100755
--- a/t/t3102-ls-tree-wildcards.sh
+++ b/t/t3102-ls-tree-wildcards.sh
@@ -12,16 +12,16 @@ test_expect_success 'setup' '
 '
 
 test_expect_success 'ls-tree a[a] matches literally' '
-	cat >expect <<-\EOF &&
-	100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391	a[a]/three
+	cat >expect <<-EOF &&
+	100644 blob $EMPTY_BLOB	a[a]/three
 	EOF
 	git ls-tree -r HEAD "a[a]" >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'ls-tree outside prefix' '
-	cat >expect <<-\EOF &&
-	100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391	../a[a]/three
+	cat >expect <<-EOF &&
+	100644 blob $EMPTY_BLOB	../a[a]/three
 	EOF
 	( cd aa && git ls-tree -r HEAD "../a[a]"; ) >actual &&
 	test_cmp expect actual
diff --git a/t/t4010-diff-pathspec.sh b/t/t4010-diff-pathspec.sh
index 43c488b545..35b35a81c8 100755
--- a/t/t4010-diff-pathspec.sh
+++ b/t/t4010-diff-pathspec.sh
@@ -78,8 +78,6 @@ test_expect_success 'diff-tree pathspec' '
 	test_cmp expected current
 '
 
-EMPTY_TREE=4b825dc642cb6eb9a060e54bf8d69288fbee4904
-
 test_expect_success 'diff-tree with wildcard shows dir also matches' '
 	git diff-tree --name-only $EMPTY_TREE $tree -- "f*" >result &&
 	echo file0 >expected &&
diff --git a/t/t4054-diff-bogus-tree.sh b/t/t4054-diff-bogus-tree.sh
index 1d6efab3c5..18f42c5fff 100755
--- a/t/t4054-diff-bogus-tree.sh
+++ b/t/t4054-diff-bogus-tree.sh
@@ -3,8 +3,6 @@
 test_description='test diff with a bogus tree containing the null sha1'
 . ./test-lib.sh
 
-empty_tree=4b825dc642cb6eb9a060e54bf8d69288fbee4904
-
 test_expect_success 'create bogus tree' '
 	bogus_tree=$(
 		printf "100644 fooQQQQQQQQQQQQQQQQQQQQQ" |
@@ -22,13 +20,13 @@ test_expect_success 'create tree with matching file' '
 
 test_expect_success 'raw diff shows null sha1 (addition)' '
 	echo ":000000 100644 $_z40 $_z40 A	foo" >expect &&
-	git diff-tree $empty_tree $bogus_tree >actual &&
+	git diff-tree $EMPTY_TREE $bogus_tree >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'raw diff shows null sha1 (removal)' '
 	echo ":100644 000000 $_z40 $_z40 D	foo" >expect &&
-	git diff-tree $bogus_tree $empty_tree >actual &&
+	git diff-tree $bogus_tree $EMPTY_TREE >actual &&
 	test_cmp expect actual
 '
 
@@ -57,11 +55,11 @@ test_expect_success 'raw diff shows null sha1 (index)' '
 '
 
 test_expect_success 'patch fails due to bogus sha1 (addition)' '
-	test_must_fail git diff-tree -p $empty_tree $bogus_tree
+	test_must_fail git diff-tree -p $EMPTY_TREE $bogus_tree
 '
 
 test_expect_success 'patch fails due to bogus sha1 (removal)' '
-	test_must_fail git diff-tree -p $bogus_tree $empty_tree
+	test_must_fail git diff-tree -p $bogus_tree $EMPTY_TREE
 '
 
 test_expect_success 'patch fails due to bogus sha1 (modification)' '
diff --git a/t/t5504-fetch-receive-strict.sh b/t/t5504-fetch-receive-strict.sh
index 44f3d5fb28..9b19cff729 100755
--- a/t/t5504-fetch-receive-strict.sh
+++ b/t/t5504-fetch-receive-strict.sh
@@ -115,8 +115,8 @@ test_expect_success 'push with transfer.fsckobjects' '
 	test_cmp exp act
 '
 
-cat >bogus-commit <<\EOF
-tree 4b825dc642cb6eb9a060e54bf8d69288fbee4904
+cat >bogus-commit <<EOF
+tree $EMPTY_TREE
 author Bugs Bunny 1234567890 +0000
 committer Bugs Bunny <bugs@bun.ni> 1234567890 +0000
 
diff --git a/t/t7011-skip-worktree-reading.sh b/t/t7011-skip-worktree-reading.sh
index 88d60c1ce2..84f41451ec 100755
--- a/t/t7011-skip-worktree-reading.sh
+++ b/t/t7011-skip-worktree-reading.sh
@@ -23,17 +23,15 @@ S sub/1
 H sub/2
 EOF
 
-NULL_SHA1=e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
-
 setup_absent() {
 	test -f 1 && rm 1
 	git update-index --remove 1 &&
-	git update-index --add --cacheinfo 100644 $NULL_SHA1 1 &&
+	git update-index --add --cacheinfo 100644 $EMPTY_BLOB 1 &&
 	git update-index --skip-worktree 1
 }
 
 test_absent() {
-	echo "100644 $NULL_SHA1 0	1" > expected &&
+	echo "100644 $EMPTY_BLOB 0	1" > expected &&
 	git ls-files --stage 1 > result &&
 	test_cmp expected result &&
 	test ! -f 1
@@ -42,12 +40,12 @@ test_absent() {
 setup_dirty() {
 	git update-index --force-remove 1 &&
 	echo dirty > 1 &&
-	git update-index --add --cacheinfo 100644 $NULL_SHA1 1 &&
+	git update-index --add --cacheinfo 100644 $EMPTY_BLOB 1 &&
 	git update-index --skip-worktree 1
 }
 
 test_dirty() {
-	echo "100644 $NULL_SHA1 0	1" > expected &&
+	echo "100644 $EMPTY_BLOB 0	1" > expected &&
 	git ls-files --stage 1 > result &&
 	test_cmp expected result &&
 	echo dirty > expected
@@ -120,7 +118,7 @@ test_expect_success 'grep with skip-worktree file' '
 	test "$(git grep --no-ext-grep test)" = "1:test"
 '
 
-echo ":000000 100644 $_z40 $NULL_SHA1 A	1" > expected
+echo ":000000 100644 $_z40 $EMPTY_BLOB A	1" > expected
 test_expect_success 'diff-index does not examine skip-worktree absent entries' '
 	setup_absent &&
 	git diff-index HEAD -- 1 > result &&
diff --git a/t/t7012-skip-worktree-writing.sh b/t/t7012-skip-worktree-writing.sh
index 9ceaa4049f..9d1abe50ef 100755
--- a/t/t7012-skip-worktree-writing.sh
+++ b/t/t7012-skip-worktree-writing.sh
@@ -53,17 +53,15 @@ test_expect_success 'read-tree removes worktree, dirty case' '
 	git update-index --no-skip-worktree added
 '
 
-NULL_SHA1=e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
-
 setup_absent() {
 	test -f 1 && rm 1
 	git update-index --remove 1 &&
-	git update-index --add --cacheinfo 100644 $NULL_SHA1 1 &&
+	git update-index --add --cacheinfo 100644 $EMPTY_BLOB 1 &&
 	git update-index --skip-worktree 1
 }
 
 test_absent() {
-	echo "100644 $NULL_SHA1 0	1" > expected &&
+	echo "100644 $EMPTY_BLOB 0	1" > expected &&
 	git ls-files --stage 1 > result &&
 	test_cmp expected result &&
 	test ! -f 1
@@ -72,12 +70,12 @@ test_absent() {
 setup_dirty() {
 	git update-index --force-remove 1 &&
 	echo dirty > 1 &&
-	git update-index --add --cacheinfo 100644 $NULL_SHA1 1 &&
+	git update-index --add --cacheinfo 100644 $EMPTY_BLOB 1 &&
 	git update-index --skip-worktree 1
 }
 
 test_dirty() {
-	echo "100644 $NULL_SHA1 0	1" > expected &&
+	echo "100644 $EMPTY_BLOB 0	1" > expected &&
 	git ls-files --stage 1 > result &&
 	test_cmp expected result &&
 	echo dirty > expected
diff --git a/t/t7063-status-untracked-cache.sh b/t/t7063-status-untracked-cache.sh
index a971884cfd..a828a5f3b4 100755
--- a/t/t7063-status-untracked-cache.sh
+++ b/t/t7063-status-untracked-cache.sh
@@ -53,7 +53,7 @@ A  two
 EOF
 
 cat >../dump.expect <<EOF &&
-info/exclude e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
+info/exclude $EMPTY_BLOB
 core.excludesfile 0000000000000000000000000000000000000000
 exclude_per_dir .gitignore
 flags 00000006
@@ -137,7 +137,7 @@ EOF
 test_expect_success 'verify untracked cache dump' '
 	test-dump-untracked-cache >../actual &&
 	cat >../expect <<EOF &&
-info/exclude e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
+info/exclude $EMPTY_BLOB
 core.excludesfile 0000000000000000000000000000000000000000
 exclude_per_dir .gitignore
 flags 00000006
@@ -184,7 +184,7 @@ EOF
 test_expect_success 'verify untracked cache dump' '
 	test-dump-untracked-cache >../actual &&
 	cat >../expect <<EOF &&
-info/exclude e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
+info/exclude $EMPTY_BLOB
 core.excludesfile 0000000000000000000000000000000000000000
 exclude_per_dir .gitignore
 flags 00000006
diff --git a/t/t7508-status.sh b/t/t7508-status.sh
index c3ed7cb51c..a42aef8317 100755
--- a/t/t7508-status.sh
+++ b/t/t7508-status.sh
@@ -803,7 +803,7 @@ EOF
 '
 
 cat >expect <<EOF
-:100644 100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0000000000000000000000000000000000000000 M	dir1/modified
+:100644 100644 $EMPTY_BLOB 0000000000000000000000000000000000000000 M	dir1/modified
 EOF
 test_expect_success 'status refreshes the index' '
 	touch dir2/added &&
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 11201e9cf8..2e5afd696a 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -162,6 +162,9 @@ _x40="$_x05$_x05$_x05$_x05$_x05$_x05$_x05$_x05"
 # Zero SHA-1
 _z40=0000000000000000000000000000000000000000
 
+EMPTY_TREE=4b825dc642cb6eb9a060e54bf8d69288fbee4904
+EMPTY_BLOB=e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
+
 # Line feed
 LF='
 '
@@ -170,7 +173,7 @@ LF='
 # when case-folding filenames
 u200c=$(printf '\342\200\214')
 
-export _x05 _x40 _z40 LF u200c
+export _x05 _x40 _z40 LF u200c EMPTY_TREE EMPTY_BLOB
 
 # Each test should start with something like this, after copyright notices:
 #