[PATCH v4 33/39] Enable SHA-256 support by default

["brian m. carlson" <sandals@crustytoothpaste.net>]

Now that the we have a complete SHA-256 implementation in Git, let's
enable it so people can use it.  Remove the ENABLE_SHA256 define
constant everywhere it's used.  Add tests for initializing a repository
with SHA-256.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 builtin/init-db.c |  5 -----
 config.mak.dev    |  2 --
 repository.c      |  4 ----
 t/t0001-init.sh   | 29 +++++++++++++++++++++++++++++
 4 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/builtin/init-db.c b/builtin/init-db.c
index cee64823cb..f70076d38e 100644
--- a/builtin/init-db.c
+++ b/builtin/init-db.c
@@ -183,11 +183,6 @@ void initialize_repository_version(int hash_algo)
 	char repo_version_string[10];
 	int repo_version = GIT_REPO_VERSION;
 
-#ifndef ENABLE_SHA256
-	if (hash_algo != GIT_HASH_SHA1)
-		die(_("The hash algorithm %s is not supported in this build."), hash_algos[hash_algo].name);
-#endif
-
 	if (hash_algo != GIT_HASH_SHA1)
 		repo_version = GIT_REPO_VERSION_READ;
 
diff --git a/config.mak.dev b/config.mak.dev
index cd4a82a9eb..89b218d11a 100644
--- a/config.mak.dev
+++ b/config.mak.dev
@@ -16,8 +16,6 @@ DEVELOPER_CFLAGS += -Wstrict-prototypes
 DEVELOPER_CFLAGS += -Wunused
 DEVELOPER_CFLAGS += -Wvla
 
-DEVELOPER_CFLAGS += -DENABLE_SHA256
-
 ifndef COMPILER_FEATURES
 COMPILER_FEATURES := $(shell ./detect-compiler $(CC))
 endif
diff --git a/repository.c b/repository.c
index 6f7f6f002b..a4174ddb06 100644
--- a/repository.c
+++ b/repository.c
@@ -89,10 +89,6 @@ void repo_set_gitdir(struct repository *repo,
 void repo_set_hash_algo(struct repository *repo, int hash_algo)
 {
 	repo->hash_algo = &hash_algos[hash_algo];
-#ifndef ENABLE_SHA256
-	if (hash_algo != GIT_HASH_SHA1)
-		die(_("The hash algorithm %s is not supported in this build."), repo->hash_algo->name);
-#endif
 }
 
 /*
diff --git a/t/t0001-init.sh b/t/t0001-init.sh
index 6d2467995e..10ed9d9235 100755
--- a/t/t0001-init.sh
+++ b/t/t0001-init.sh
@@ -441,6 +441,35 @@ test_expect_success 're-init from a linked worktree' '
 	)
 '
 
+test_expect_success 'init honors GIT_DEFAULT_HASH' '
+	GIT_DEFAULT_HASH=sha1 git init sha1 &&
+	git -C sha1 rev-parse --show-object-format >actual &&
+	echo sha1 >expected &&
+	test_cmp expected actual &&
+	GIT_DEFAULT_HASH=sha256 git init sha256 &&
+	git -C sha256 rev-parse --show-object-format >actual &&
+	echo sha256 >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'init honors --object-format' '
+	git init --object-format=sha256 explicit &&
+	git -C explicit rev-parse --show-object-format >actual &&
+	echo sha256 >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'extensions.objectFormat is not allowed with repo version 0' '
+	git init --object-format=sha256 explicit-v0 &&
+	git -C explicit-v0 config core.repositoryformatversion 0 &&
+	test_must_fail git -C explicit-v0 rev-parse --show-object-format
+'
+
+test_expect_success 'init rejects attempts to initialize with different hash' '
+	test_must_fail git -C sha1 init --object-format=sha256 &&
+	test_must_fail git -C sha256 init --object-format=sha1
+'
+
 test_expect_success MINGW 'core.hidedotfiles = false' '
 	git config --global core.hidedotfiles false &&
 	rm -rf newdir &&