patchgrep: ignore --recurse-submodules if --no-index is given

From: Philippe Blain <levraiphilippeblain@gmail.com>

Since grep learned to recurse into submodules in 0281e487fd (grep: optionally recurse into submodules, 2016-12-16), using --recurse-submodules along with --no-index makes Git die().

This is unfortunate because if submodule.recurse is set in a user's ~/.gitconfig, invoking `git grep --no-index` either inside or outside a Git repository results in

    fatal: option not supported with --recurse-submodules

Let's allow using these options together, so that setting submodule.recurse globally does not prevent using `git grep --no-index`.

Using `--recurse-submodules` should not have any effect if `--no-index` is used inside a repository, as Git will recurse into the checked out submodule directories just like into regular directories.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
    grep: ignore --recurse-submodules if --no-index is given
    
    Since grep learned to recurse into submodules in 0281e487fd (grep:
    optionally recurse into submodules, 2016-12-16), using
    --recurse-submodules along with --no-index makes Git die().
    
    This is unfortunate because if submodule.recurse is set in a user's
    ~/.gitconfig, invoking git grep --no-index either inside or outside a
    Git repository results in
    
    fatal: option not supported with --recurse-submodules
    
    Let's allow using these options together, so that setting
    submodule.recurse globally does not prevent using git grep --no-index.
    
    Using --recurse-submodules should not have any effect if --no-indexis
    used inside a repository, as Git will recurse into the checked out
    submodule directories just like into regular directories.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-540%2Fphil-blain%2Fgrep-no-index-ignore-recurse-submodule-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-540/phil-blain/grep-no-index-ignore-recurse-submodule-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/540

 Documentation/git-grep.txt         |  3 ++-
 builtin/grep.c                     |  4 ++--
 t/t7814-grep-recurse-submodules.sh | 11 ++++++++++-
 3 files changed, 14 insertions(+), 4 deletions(-)

Hi Philippe,

On Sun, 26 Jan 2020, Philippe Blain via GitGitGadget wrote:

My initial reaction to this patch was: "but why would you try to combine `--recurse-submodules` with `--no-index`?". The `submodule.recurse` reference made me think again, though.

And then it hit me: by `--no-index`, what we _really_ mean to say is: ignore that this _might_ be tracked in Git. And that obviously means that there cannot be any submodules to recurse into, as far as `git diff --no-index` is concerned.

So I think your patch makes a ton of sense.

Thanks, Dscho

From: Philippe Blain <levraiphilippeblain@gmail.com>

Since grep learned to recurse into submodules in 0281e487fd (grep: optionally recurse into submodules, 2016-12-16), using --recurse-submodules along with --no-index makes Git die().

This is unfortunate because if submodule.recurse is set in a user's ~/.gitconfig, invoking `git grep --no-index` either inside or outside a Git repository results in

    fatal: option not supported with --recurse-submodules

Let's allow using these options together, so that setting submodule.recurse globally does not prevent using `git grep --no-index`.

Using `--recurse-submodules` should not have any effect if `--no-index` is used inside a repository, as Git will recurse into the checked out submodule directories just like into regular directories.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
    grep: ignore --recurse-submodules if --no-index is given
    
    Changes since v1:
    
     * set recurse_submodules to 0 early in cmd_grep if !use_index. This
       makes more sense, and eliminates an incompatibility with topic
       mt/threaded-grep-in-object-store.
    
    v1: Since grep learned to recurse into submodules in 0281e487fd (grep:
    optionally recurse into submodules, 2016-12-16), using
    --recurse-submodules along with --no-index makes Git die().
    
    This is unfortunate because if submodule.recurse is set in a user's
    ~/.gitconfig, invoking git grep --no-index either inside or outside a
    Git repository results in
    
    fatal: option not supported with --recurse-submodules
    
    Let's allow using these options together, so that setting
    submodule.recurse globally does not prevent using git grep --no-index.
    
    Using --recurse-submodules should not have any effect if --no-indexis
    used inside a repository, as Git will recurse into the checked out
    submodule directories just like into regular directories.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-540%2Fphil-blain%2Fgrep-no-index-ignore-recurse-submodule-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-540/phil-blain/grep-no-index-ignore-recurse-submodule-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/540

Range-diff vs v1:

 1:  6634266b01 ! 1:  6fc8bf788a grep: ignore --recurse-submodules if --no-index is given
     @@ -20,6 +20,7 @@
          is used inside a repository, as Git will recurse into the checked out
          submodule directories just like into regular directories.
      
     +    Helped-by: Junio C Hamano <gitster@pobox.com>
          Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
      
       diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
     @@ -39,6 +40,16 @@
       diff --git a/builtin/grep.c b/builtin/grep.c
       --- a/builtin/grep.c
       +++ b/builtin/grep.c
     +@@
     + 			/* die the same way as if we did it at the beginning */
     + 			setup_git_directory();
     + 	}
     ++	/* Ignore --recurse-submodules if --no-index is given or implied */
     ++	if (!use_index)
     ++		recurse_submodules = 0;
     + 
     + 	/*
     + 	 * skip a -- separator; we know it cannot be
      @@
       		}
       	}

 Documentation/git-grep.txt         |  3 ++-
 builtin/grep.c                     |  7 +++++--
 t/t7814-grep-recurse-submodules.sh | 11 ++++++++++-
 3 files changed, 17 insertions(+), 4 deletions(-)

"Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com> writes:

This is done quite early in the execution flow. That makes any and all existing checks that says "if recurse-submodules is set and we are in no-index mode, do this" unneeded.

And this is an example of a change to remove a check for such a redundant condition. If recurse_submodules is true (which is the only time the RHS of &&- is evaluated), we know use_index cannot be false, so the final outcome solely depends on the value of untracked.

Looks good. And my quick reading of the current builtin/grep.c code suggests that this is the only such combination that can be simplified.

Thanks.