line-log: fix -L with pickaxe options

This series fixes a crash in git log -L when combined with pickaxe options (-G, -S, or --find-object) on a history involving renames, reported in [1].

The crash bisects to a2bb801f6a (line-log: avoid unnecessary full tree diffs, 2019-08-21). Before that commit, the same combination silently truncated history at rename boundaries rather than crashing. The root cause is that diffcore_std() runs diffcore_pickaxe(), which may discard diff pairs needed for rename detection.

Patch 1 fixes the crash by calling diffcore_rename() directly instead of diffcore_std(), and adds tests including known-breakage markers showing that the pickaxe options are silently ignored by -L.

Patch 2 explicitly rejects the unsupported combination with die(), replacing the known-breakage tests with rejection tests.

[1] https://lore.kernel.org/git/aac-QdjY1ohAqgw_@desktop/

Michael Montalbo (2):
line-log: fix crash when combined with pickaxe options
log: reject pickaxe options when combined with -L

 builtin/log.c       |  4 ++++
 line-log.c          |  8 +++++++-
 t/t4211-line-log.sh | 15 +++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

base-commit: 67ad42147a7acc2af6074753ebd03d904476118f
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2061%2Fmmontalbo%2Ffix-line-log-G-crash-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2061/mmontalbo/fix-line-log-G-crash-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/2061

Range-diff vs v1:

1: 6e97d88993 ! 1: 273ebf640d line-log: fix crash when combined with pickaxe options
@@ Commit message
Before a2bb801f6a (line-log: avoid unnecessary full tree diffs, 2019-08-21), diffcore_std() was only invoked when a rename was already suspected, so the pickaxe interference was unlikely in practice. That
- commit made the diffcore_std() call unconditional, and with
- filter_diffs_for_paths() now framing that call, a queue pruned by
- pickaxe violates filter_diffs_for_paths()'s expectation that diff
- pairs correspond to tracked paths, triggering an assertion failure.
+ commit restructured queue_diffs() to gate both diffcore_std() and the
+ surrounding filter_diffs_for_paths() calls behind
+ diff_might_be_rename(). When pickaxe breaks rename following at one
+ commit, a later commit may produce a deletion pair that bypasses this
+ gate entirely, reaching process_diff_filepair() with an invalid
+ filespec and triggering an assertion failure.

Fix this by calling diffcore_rename() directly instead of diffcore_std(). The line-log machinery only needs rename detection
2: ae5269af0b = 2: 81cb521401 log: reject pickaxe options when combined with -L

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