Merge branch 'jc/no-lazy-fetch' into HEAD

"git --no-lazy-fetch cmd" allows to run "cmd" while disabling lazy
fetching of objects from the promisor remote, which may be handy
for debugging.

* jc/no-lazy-fetch:
  git: extend --no-lazy-fetch to work across subprocesses
  git: document GIT_NO_REPLACE_OBJECTS environment variable
  git: --no-lazy-fetch option

Documentation/git.txt

@@ -174,8 +174,17 @@ If you just want to run git as if it was started in `<path>` then use
 	directory.
 
 --no-replace-objects::
-	Do not use replacement refs to replace Git objects. See
-	linkgit:git-replace[1] for more information.
+	Do not use replacement refs to replace Git objects.
+	This is equivalent to exporting the `GIT_NO_REPLACE_OBJECTS`
+	environment variable with any value.
+	See linkgit:git-replace[1] for more information.
+
+--no-lazy-fetch::
+	Do not fetch missing objects from the promisor remote on
+	demand.  Useful together with `git cat-file -e <object>` to
+	see if the object is locally available.
+	This is equivalent to setting the `GIT_NO_LAZY_FETCH`
+	environment variable to `1`.
 
 --literal-pathspecs::
 	Treat pathspecs literally (i.e. no globbing, no pathspec magic).
@@ -872,6 +881,10 @@ for full details.
 	header and packfile URIs. Set this Boolean environment variable to false to prevent this
 	redaction.
 
+`GIT_NO_REPLACE_OBJECTS`::
+	Setting and exporting this environment variable tells Git to
+	ignore replacement refs and do not replace Git objects.
+
 `GIT_LITERAL_PATHSPECS`::
 	Setting this Boolean environment variable to true will cause Git to treat all
 	pathspecs literally, rather than as glob patterns. For example,
@@ -893,6 +906,11 @@ for full details.
 	Setting this Boolean environment variable to true will cause Git to treat all
 	pathspecs as case-insensitive.
 
+`GIT_NO_LAZY_FETCH`::
+	Setting this Boolean environment variable to true tells Git
+	not to lazily fetch missing objects from the promisor remote
+	on demand.
+
 `GIT_REFLOG_ACTION`::
 	When a ref is updated, reflog entries are created to keep
 	track of the reason why the ref was updated (which is

environment.c

@@ -207,6 +207,9 @@ void setup_git_env(const char *git_dir)
 	shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);
 	if (shallow_file)
 		set_alternate_shallow_file(the_repository, shallow_file, 0);
+
+	if (git_env_bool(NO_LAZY_FETCH_ENVIRONMENT, 0))
+		fetch_if_missing = 0;
 }
 
 int is_bare_repository(void)

environment.h

@@ -36,6 +36,7 @@ const char *getenv_safe(struct strvec *argv, const char *name);
 #define CEILING_DIRECTORIES_ENVIRONMENT "GIT_CEILING_DIRECTORIES"
 #define NO_REPLACE_OBJECTS_ENVIRONMENT "GIT_NO_REPLACE_OBJECTS"
 #define GIT_REPLACE_REF_BASE_ENVIRONMENT "GIT_REPLACE_REF_BASE"
+#define NO_LAZY_FETCH_ENVIRONMENT "GIT_NO_LAZY_FETCH"
 #define GITATTRIBUTES_FILE ".gitattributes"
 #define INFOATTRIBUTES_FILE "info/attributes"
 #define ATTRIBUTE_MACRO_PREFIX "[attr]"

git.c

@@ -4,6 +4,7 @@
 #include "exec-cmd.h"
 #include "gettext.h"
 #include "help.h"
+#include "object-file.h"
 #include "pager.h"
 #include "read-cache-ll.h"
 #include "run-command.h"
@@ -186,6 +187,11 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			use_pager = 0;
 			if (envchanged)
 				*envchanged = 1;
+		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
+			fetch_if_missing = 0;
+			setenv(NO_LAZY_FETCH_ENVIRONMENT, "1", 1);
+			if (envchanged)
+				*envchanged = 1;
 		} else if (!strcmp(cmd, "--no-replace-objects")) {
 			disable_replace_refs();
 			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);

t/t0410-partial-clone.sh

@@ -665,6 +665,21 @@ test_expect_success 'lazy-fetch when accessing object not in the_repository' '
 	git -C partial.git rev-list --objects --missing=print HEAD >out &&
 	grep "[?]$FILE_HASH" out &&
 
+	# The no-lazy-fetch mechanism prevents Git from fetching
+	test_must_fail env GIT_NO_LAZY_FETCH=1 \
+		git -C partial.git cat-file -e "$FILE_HASH" &&
+
+	# The same with command line option to "git"
+	test_must_fail git --no-lazy-fetch -C partial.git cat-file -e "$FILE_HASH" &&
+
+	# The same, forcing a subprocess via an alias
+	test_must_fail git --no-lazy-fetch -C partial.git \
+		-c alias.foo="!git cat-file" foo -e "$FILE_HASH" &&
+
+	# Sanity check that the file is still missing
+	git -C partial.git rev-list --objects --missing=print HEAD >out &&
+	grep "[?]$FILE_HASH" out &&
+
 	git -C full cat-file -s "$FILE_HASH" >expect &&
 	test-tool partial-clone object-info partial.git "$FILE_HASH" >actual &&
 	test_cmp expect actual &&