[PATCH v2 3/3] rev-parse: match ^{<type>} case-insensitively

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change the revision parsing logic to match ^{commit}, ^{tree}, ^{blob}
etc. case-insensitively.

Before this change supplying anything except the lower-case forms
emits an "unknown revision or path not in the working tree"
error. This change makes upper-case & mixed-case versions equivalent
to the lower-case versions.

The rationale for this change is the same as for making @{upstream}
and related suffixes case-insensitive in "rev-parse: match
@{upstream}, @{u} and @{push} case-insensitively", but unlike those
suffixes this change introduces the potential confusion of accepting
TREE or BLOB here, but not as an argument to e.g. "cat-file -t <type>"
or "hash-object -t <type>".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/revisions.txt |  5 +++++
 git-compat-util.h           |  1 +
 sha1_name.c                 | 10 +++++-----
 strbuf.c                    |  9 +++++++++
 t/t1450-fsck.sh             |  7 +++++++
 t/t1511-rev-parse-caret.sh  | 13 +++++++++++++
 6 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt
index 5fe90e411d..136e26c05d 100644
--- a/Documentation/revisions.txt
+++ b/Documentation/revisions.txt
@@ -162,6 +162,11 @@ it does not have to be dereferenced even once to get to an object.
 +
 'rev{caret}\{tag\}' can be used to ensure that 'rev' identifies an
 existing tag object.
++
+The {caret}{<type>} part is matched case-insensitively. So
+e.g. '{caret}\{commit\}' can be equivalently specified as
+'{caret}\{COMMIT\}', '{caret}\{Commit\}' etc., '{caret}\{tree\}' as
+'{caret}\{TREE\}' and so forth.
 
 '<rev>{caret}{}', e.g. 'v0.99.8{caret}{}'::
   A suffix '{caret}' followed by an empty brace pair
diff --git a/git-compat-util.h b/git-compat-util.h
index 8a4a3f85e7..4a03934ef3 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -448,6 +448,7 @@ extern void set_die_is_recursing_routine(int (*routine)(void));
 extern void set_error_handle(FILE *);
 
 extern int starts_with(const char *str, const char *prefix);
+extern int starts_with_icase(const char *str, const char *prefix);
 
 /*
  * If the string "str" begins with the string found in "prefix", return 1.
diff --git a/sha1_name.c b/sha1_name.c
index 2deb9bfdf6..107246bd2d 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -821,15 +821,15 @@ static int peel_onion(const char *name, int len, unsigned char *sha1,
 		return -1;
 
 	sp++; /* beginning of type name, or closing brace for empty */
-	if (starts_with(sp, "commit}"))
+	if (starts_with_icase(sp, "commit}"))
 		expected_type = OBJ_COMMIT;
-	else if (starts_with(sp, "tag}"))
+	else if (starts_with_icase(sp, "tag}"))
 		expected_type = OBJ_TAG;
-	else if (starts_with(sp, "tree}"))
+	else if (starts_with_icase(sp, "tree}"))
 		expected_type = OBJ_TREE;
-	else if (starts_with(sp, "blob}"))
+	else if (starts_with_icase(sp, "blob}"))
 		expected_type = OBJ_BLOB;
-	else if (starts_with(sp, "object}"))
+	else if (starts_with_icase(sp, "object}"))
 		expected_type = OBJ_ANY;
 	else if (sp[0] == '}')
 		expected_type = OBJ_NONE;
diff --git a/strbuf.c b/strbuf.c
index ace58e7367..7d4a59bca6 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -11,6 +11,15 @@ int starts_with(const char *str, const char *prefix)
 			return 0;
 }
 
+int starts_with_icase(const char *str, const char *prefix)
+{
+	for (; ; str++, prefix++)
+		if (!*prefix)
+			return 1;
+		else if (tolower(*str) != tolower(*prefix))
+			return 0;
+}
+
 /*
  * Used as the default ->buf value, so that people can always assume
  * buf is non NULL and ->buf is NUL terminated even for a freshly
diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh
index 33a51c9a67..b6c1989671 100755
--- a/t/t1450-fsck.sh
+++ b/t/t1450-fsck.sh
@@ -505,6 +505,13 @@ test_expect_success 'fsck notices missing tagged object' '
 	test_must_fail git -C missing fsck
 '
 
+test_expect_success 'fsck notices missing tagged object with case insensitive {blob}' '
+	create_repo_missing tag^{BLOB} &&
+	test_must_fail git -C missing fsck &&
+	create_repo_missing tag^{BloB} &&
+	test_must_fail git -C missing fsck
+'
+
 test_expect_success 'fsck notices ref pointing to missing commit' '
 	create_repo_missing HEAD &&
 	test_must_fail git -C missing fsck
diff --git a/t/t1511-rev-parse-caret.sh b/t/t1511-rev-parse-caret.sh
index e0a49a651f..56750f99c6 100755
--- a/t/t1511-rev-parse-caret.sh
+++ b/t/t1511-rev-parse-caret.sh
@@ -48,6 +48,10 @@ test_expect_success 'ref^{commit}' '
 	git rev-parse ref >expected &&
 	git rev-parse ref^{commit} >actual &&
 	test_cmp expected actual &&
+	git rev-parse ref^{COMMIT} >actual &&
+	test_cmp expected actual &&
+	git rev-parse ref^{CoMMiT} >actual &&
+	test_cmp expected actual &&
 	git rev-parse commit-tag^{commit} >actual &&
 	test_cmp expected actual &&
 	test_must_fail git rev-parse tree-tag^{commit} &&
@@ -58,6 +62,10 @@ test_expect_success 'ref^{tree}' '
 	echo $TREE_SHA1 >expected &&
 	git rev-parse ref^{tree} >actual &&
 	test_cmp expected actual &&
+	git rev-parse ref^{TREE} >actual &&
+	test_cmp expected actual &&
+	git rev-parse ref^{TrEe} >actual &&
+	test_cmp expected actual &&
 	git rev-parse commit-tag^{tree} >actual &&
 	test_cmp expected actual &&
 	git rev-parse tree-tag^{tree} >actual &&
@@ -67,8 +75,13 @@ test_expect_success 'ref^{tree}' '
 
 test_expect_success 'ref^{tag}' '
 	test_must_fail git rev-parse HEAD^{tag} &&
+	test_must_fail git rev-parse HEAD^{TAG} &&
 	git rev-parse commit-tag >expected &&
 	git rev-parse commit-tag^{tag} >actual &&
+	test_cmp expected actual &&
+	git rev-parse commit-tag^{TAG} >actual &&
+	test_cmp expected actual &&
+	git rev-parse commit-tag^{Tag} >actual &&
 	test_cmp expected actual
 '
 
-- 
2.11.0