merge-recursive: options to ignore whitespace changes

Add support for merging with ignoring line endings (specifically
--ignore-space-at-eol) when using recursive merging.  This is
as a strategy-option, so that you can do:

	git merge --strategy-option=ignore-space-at-eol <branch>

and

	git rebase --strategy-option=ignore-space-at-eol <branch>

This can be useful for coping with line-ending damage (Xcode 3.1 has a
nasty habit of converting all CRLFs to LFs, and VC6 tends to just use
CRLFs for inserted lines).

The only option I need is ignore-space-at-eol, but while at it,
include the other xdiff whitespace options (ignore-space-change,
ignore-all-space), too.

[jn: with documentation]

Signed-off-by: Justin Frankel <justin@cockos.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 207 insertions, 0 deletions

diff --git a/Documentation/merge-strategies.txt b/Documentation/merge-strategies.txt
index a5ae14fba5..91faba5da9 100644
--- a/Documentation/merge-strategies.txt
+++ b/Documentation/merge-strategies.txt
@@ -47,6 +47,21 @@ patience;;
 	this when the branches to be merged have diverged wildly.
 	See also linkgit:git-diff[1] `--patience`.
 
+ignore-space-change;;
+ignore-all-space;;
+ignore-space-at-eol;;
+	Treats lines with the indicated type of whitespace change as
+	unchanged for the sake of a three-way merge.  Whitespace
+	changes mixed with other changes to a line are not ignored.
+	See also linkgit:git-diff[1] `-b`, `-w`, and
+	`--ignore-space-at-eol`.
++
+* If 'their' version only introduces whitespace changes to a line,
+  'our' version is used;
+* If 'our' version introduces whitespace changes but 'their'
+  version includes a substantial change, 'their' version is used;
+* Otherwise, the merge proceeds in the usual way.
+
 renormalize;;
 	This runs a virtual check-out and check-in of all three stages
 	of a file when resolving a three-way merge.  This option is
diff --git a/merge-recursive.c b/merge-recursive.c
index 3e67f8145f..9b9f97e6af 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1515,6 +1515,12 @@ int parse_merge_opt(struct merge_options *o, const char *s)
 		o->subtree_shift = s + strlen("subtree=");
 	else if (!strcmp(s, "patience"))
 		o->xdl_opts |= XDF_PATIENCE_DIFF;
+	else if (!strcmp(s, "ignore-space-change"))
+		o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
+	else if (!strcmp(s, "ignore-all-space"))
+		o->xdl_opts |= XDF_IGNORE_WHITESPACE;
+	else if (!strcmp(s, "ignore-space-at-eol"))
+		o->xdl_opts |= XDF_IGNORE_WHITESPACE_AT_EOL;
 	else if (!strcmp(s, "renormalize"))
 		o->renormalize = 1;
 	else if (!strcmp(s, "no-renormalize"))
diff --git a/t/t3032-merge-recursive-options.sh b/t/t3032-merge-recursive-options.sh
new file mode 100755
index 0000000000..2293797553
--- /dev/null
+++ b/t/t3032-merge-recursive-options.sh
@@ -0,0 +1,186 @@
+#!/bin/sh
+
+test_description='merge-recursive options
+
+* [master] Clarify
+ ! [remote] Remove cruft
+--
+ + [remote] Remove cruft
+*  [master] Clarify
+*+ [remote^] Initial revision
+*   ok 1: setup
+'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	conflict_hunks () {
+		sed -n -e "
+			/^<<<</ b inconflict
+			b
+			: inconflict
+			p
+			/^>>>>/ b
+			n
+			b inconflict
+		" "$@"
+	} &&
+
+	cat <<-\EOF >text.txt &&
+	    Hope, he says, cherishes the soul of him who lives in
+	    justice and holiness and is the nurse of his age and the
+	    companion of his journey;--hope which is mightiest to sway
+	    the restless soul of man.
+
+	How admirable are his words!  And the great blessing of riches, I do
+	not say to every man, but to a good man, is, that he has had no
+	occasion to deceive or to defraud others, either intentionally or
+	unintentionally; and when he departs to the world below he is not in
+	any apprehension about offerings due to the gods or debts which he owes
+	to men.  Now to this peace of mind the possession of wealth greatly
+	contributes; and therefore I say, that, setting one thing against
+	another, of the many advantages which wealth has to give, to a man of
+	sense this is in my opinion the greatest.
+
+	Well said, Cephalus, I replied; but as concerning justice, what is
+	it?--to speak the truth and to pay your debts--no more than this?  And
+	even to this are there not exceptions?  Suppose that a friend when in
+	his right mind has deposited arms with me and he asks for them when he
+	is not in his right mind, ought I to give them back to him?  No one
+	would say that I ought or that I should be right in doing so, any more
+	than they would say that I ought always to speak the truth to one who
+	is in his condition.
+
+	You are quite right, he replied.
+
+	But then, I said, speaking the truth and paying your debts is not a
+	correct definition of justice.
+
+	CEPHALUS - SOCRATES - POLEMARCHUS
+
+	Quite correct, Socrates, if Simonides is to be believed, said
+	Polemarchus interposing.
+
+	I fear, said Cephalus, that I must go now, for I have to look after the
+	sacrifices, and I hand over the argument to Polemarchus and the company.
+	EOF
+	git add text.txt &&
+	test_tick &&
+	git commit -m "Initial revision" &&
+
+	git checkout -b remote &&
+	sed -e "
+			s/\.  /\. /g
+			s/[?]  /? /g
+			s/    /	/g
+			s/--/---/g
+			s/but as concerning/but as con cerning/
+			/CEPHALUS - SOCRATES - POLEMARCHUS/ d
+		" text.txt >text.txt+ &&
+	mv text.txt+ text.txt &&
+	git commit -a -m "Remove cruft" &&
+
+	git checkout master &&
+	sed -e "
+			s/\(not in his right mind\),\(.*\)/\1;\2Q/
+			s/Quite correct\(.*\)/It is too correct\1Q/
+			s/unintentionally/un intentionally/
+			/un intentionally/ s/$/Q/
+			s/Polemarchus interposing./Polemarchus, interposing.Q/
+			/justice and holiness/ s/$/Q/
+			/pay your debts/ s/$/Q/
+		" text.txt | q_to_cr >text.txt+ &&
+	mv text.txt+ text.txt &&
+	git commit -a -m "Clarify" &&
+	git show-branch --all
+'
+
+test_expect_success 'naive merge fails' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive HEAD^ -- HEAD remote &&
+	test_must_fail git update-index --refresh &&
+	grep "<<<<<<" text.txt
+'
+
+test_expect_success '--ignore-space-change makes merge succeed' '
+	git read-tree --reset -u HEAD &&
+	git merge-recursive --ignore-space-change HEAD^ -- HEAD remote
+'
+
+test_expect_success '--ignore-space-change: our w/s-only change wins' '
+	q_to_cr <<-\EOF >expected &&
+	    justice and holiness and is the nurse of his age and theQ
+	EOF
+
+	git read-tree --reset -u HEAD &&
+	git merge-recursive --ignore-space-change HEAD^ -- HEAD remote &&
+	grep "justice and holiness" text.txt >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success '--ignore-space-change: their real change wins over w/s' '
+	cat <<-\EOF >expected &&
+	it?---to speak the truth and to pay your debts---no more than this? And
+	EOF
+
+	git read-tree --reset -u HEAD &&
+	git merge-recursive --ignore-space-change HEAD^ -- HEAD remote &&
+	grep "pay your debts" text.txt >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success '--ignore-space-change: does not ignore new spaces' '
+	cat <<-\EOF >expected1 &&
+	Well said, Cephalus, I replied; but as con cerning justice, what is
+	EOF
+	q_to_cr <<-\EOF >expected2 &&
+	un intentionally; and when he departs to the world below he is not inQ
+	EOF
+
+	git read-tree --reset -u HEAD &&
+	git merge-recursive --ignore-space-change HEAD^ -- HEAD remote &&
+	grep "Well said" text.txt >actual1 &&
+	grep "when he departs" text.txt >actual2 &&
+	test_cmp expected1 actual1 &&
+	test_cmp expected2 actual2
+'
+
+test_expect_success '--ignore-all-space drops their new spaces' '
+	cat <<-\EOF >expected &&
+	Well said, Cephalus, I replied; but as concerning justice, what is
+	EOF
+
+	git read-tree --reset -u HEAD &&
+	git merge-recursive --ignore-all-space HEAD^ -- HEAD remote &&
+	grep "Well said" text.txt >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success '--ignore-all-space keeps our new spaces' '
+	q_to_cr <<-\EOF >expected &&
+	un intentionally; and when he departs to the world below he is not inQ
+	EOF
+
+	git read-tree --reset -u HEAD &&
+	git merge-recursive --ignore-all-space HEAD^ -- HEAD remote &&
+	grep "when he departs" text.txt >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success '--ignore-space-at-eol' '
+	q_to_cr <<-\EOF >expected &&
+	<<<<<<< HEAD
+	is not in his right mind; ought I to give them back to him?  No oneQ
+	=======
+	is not in his right mind, ought I to give them back to him? No one
+	>>>>>>> remote
+	EOF
+
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --ignore-space-at-eol \
+						 HEAD^ -- HEAD remote &&
+	conflict_hunks text.txt >actual &&
+	test_cmp expected actual
+'
+
+test_done