From 10c64a0b3c15391180c31d1217ba01d687558757 Mon Sep 17 00:00:00 2001 From: Jonathan Tan Date: Mon, 2 Dec 2019 11:57:51 -0800 Subject: [PATCH 1/2] Doc: explain submodule.alternateErrorStrategy Commit 31224cbdc7 ("clone: recursive and reference option triggers submodule alternates", 2016-08-17) taught Git to support the configuration options "submodule.alternateLocation" and "submodule.alternateErrorStrategy" on a superproject. If "submodule.alternateLocation" is configured to "superproject" on a superproject, whenever a submodule of that superproject is cloned, it instead computes the analogous alternate path for that submodule from $GIT_DIR/objects/info/alternates of the superproject, and references it. The "submodule.alternateErrorStrategy" option determines what happens if that alternate cannot be referenced. However, it is not clear that the clone proceeds as if no alternate was specified when that option is not set to "die" (as can be seen in the tests in 31224cbdc7). Therefore, document it accordingly. Signed-off-by: Jonathan Tan Acked-by: Jeff King Signed-off-by: Junio C Hamano --- Documentation/config/submodule.txt | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/Documentation/config/submodule.txt b/Documentation/config/submodule.txt index 0a1293b051..b33177151c 100644 --- a/Documentation/config/submodule.txt +++ b/Documentation/config/submodule.txt @@ -79,4 +79,6 @@ submodule.alternateLocation:: submodule.alternateErrorStrategy:: Specifies how to treat errors with the alternates for a submodule as computed via `submodule.alternateLocation`. Possible values are - `ignore`, `info`, `die`. Default is `die`. + `ignore`, `info`, `die`. Default is `die`. Note that if set to `ignore` + or `info`, and if there is an error with the computed alternate, the + clone proceeds as if no alternate was specified. From 4f3e57ef13d0ad4c00d0a87f0858cde81456a2e0 Mon Sep 17 00:00:00 2001 From: Jonathan Tan Date: Mon, 2 Dec 2019 11:57:52 -0800 Subject: [PATCH 2/2] submodule--helper: advise on fatal alternate error When recursively cloning a superproject with some shallow modules defined in its .gitmodules, then recloning with "--reference=", an error occurs. For example: git clone --recurse-submodules --branch=master -j8 \ https://android.googlesource.com/platform/superproject \ master git clone --recurse-submodules --branch=master -j8 \ https://android.googlesource.com/platform/superproject \ --reference master master2 fails with: fatal: submodule '' cannot add alternate: reference repository '' is shallow When a alternate computed from the superproject's alternate cannot be added, whether in this case or another, advise about configuring the "submodule.alternateErrorStrategy" configuration option and using "--reference-if-able" instead of "--reference" when cloning. Signed-off-by: Jonathan Tan Acked-by: Jeff King Signed-off-by: Junio C Hamano --- Documentation/config/advice.txt | 3 +++ advice.c | 2 ++ advice.h | 1 + builtin/submodule--helper.c | 10 ++++++++++ 4 files changed, 16 insertions(+) diff --git a/Documentation/config/advice.txt b/Documentation/config/advice.txt index 6aaa360202..d4e698cd3f 100644 --- a/Documentation/config/advice.txt +++ b/Documentation/config/advice.txt @@ -107,4 +107,7 @@ advice.*:: editor input from the user. nestedTag:: Advice shown if a user attempts to recursively tag a tag object. + submoduleAlternateErrorStrategyDie: + Advice shown when a submodule.alternateErrorStrategy option + configured to "die" causes a fatal error. -- diff --git a/advice.c b/advice.c index 3ee0ee2d8f..249c60dcf3 100644 --- a/advice.c +++ b/advice.c @@ -30,6 +30,7 @@ int advice_waiting_for_editor = 1; int advice_graft_file_deprecated = 1; int advice_checkout_ambiguous_remote_branch_name = 1; int advice_nested_tag = 1; +int advice_submodule_alternate_error_strategy_die = 1; static int advice_use_color = -1; static char advice_colors[][COLOR_MAXLEN] = { @@ -89,6 +90,7 @@ static struct { { "graftFileDeprecated", &advice_graft_file_deprecated }, { "checkoutAmbiguousRemoteBranchName", &advice_checkout_ambiguous_remote_branch_name }, { "nestedTag", &advice_nested_tag }, + { "submoduleAlternateErrorStrategyDie", &advice_submodule_alternate_error_strategy_die }, /* make this an alias for backward compatibility */ { "pushNonFastForward", &advice_push_update_rejected } diff --git a/advice.h b/advice.h index d015404843..b706780614 100644 --- a/advice.h +++ b/advice.h @@ -30,6 +30,7 @@ extern int advice_waiting_for_editor; extern int advice_graft_file_deprecated; extern int advice_checkout_ambiguous_remote_branch_name; extern int advice_nested_tag; +extern int advice_submodule_alternate_error_strategy_die; int git_default_advice_config(const char *var, const char *value); __attribute__((format (printf, 1, 2))) diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c index 2c2395a620..12d546dfbb 100644 --- a/builtin/submodule--helper.c +++ b/builtin/submodule--helper.c @@ -19,6 +19,7 @@ #include "diffcore.h" #include "diff.h" #include "object-store.h" +#include "advice.h" #define OPT_QUIET (1 << 0) #define OPT_CACHED (1 << 1) @@ -1268,6 +1269,13 @@ struct submodule_alternate_setup { #define SUBMODULE_ALTERNATE_SETUP_INIT { NULL, \ SUBMODULE_ALTERNATE_ERROR_IGNORE, NULL } +static const char alternate_error_advice[] = N_( +"An alternate computed from a superproject's alternate is invalid.\n" +"To allow Git to clone without an alternate in such a case, set\n" +"submodule.alternateErrorStrategy to 'info' or, equivalently, clone with\n" +"'--reference-if-able' instead of '--reference'." +); + static int add_possible_reference_from_superproject( struct object_directory *odb, void *sas_cb) { @@ -1299,6 +1307,8 @@ static int add_possible_reference_from_superproject( } else { switch (sas->error_mode) { case SUBMODULE_ALTERNATE_ERROR_DIE: + if (advice_submodule_alternate_error_strategy_die) + advise(_(alternate_error_advice)); die(_("submodule '%s' cannot add alternate: %s"), sas->submodule_name, err.buf); case SUBMODULE_ALTERNATE_ERROR_INFO: