patch, 10 parts[RFC] pickaxe for function names

diff --git a/.gitattributes b/.gitattributes
index 5e98806..320e33c 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,3 +1,3 @@
 * whitespace=!indent,trail,space
-*.[ch] whitespace=indent,trail,space
+*.[ch] whitespace=indent,trail,space diff=cpp
 *.sh whitespace=indent,trail,space

diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index 401eb72..0d36a3c 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -12,6 +12,8 @@ typedef int (*pickaxe_fn)(mmfile_t *one, mmfile_t *two,
 			  struct diff_options *o,
 			  regex_t *regexp, kwset_t kws);
 
+static void compile_regex(regex_t *r, const char *s, int cflags);
+
 static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,
 			 regex_t *regexp, kwset_t kws, pickaxe_fn fn);
 
@@ -110,20 +112,13 @@ static int diff_grep(mmfile_t *one, mmfile_t *two,
 
 static void diffcore_pickaxe_grep(struct diff_options *o)
 {
-	int err;
 	regex_t regex;
 	int cflags = REG_EXTENDED | REG_NEWLINE;
 
 	if (DIFF_OPT_TST(o, PICKAXE_IGNORE_CASE))
 		cflags |= REG_ICASE;
 
-	err = regcomp(&regex, o->pickaxe, cflags);
-	if (err) {
-		char errbuf[1024];
-		regerror(err, &regex, errbuf, 1024);
-		regfree(&regex);
-		die("invalid regex: %s", errbuf);
-	}
+	compile_regex(&regex, o->pickaxe, cflags);
 
 	pickaxe(&diff_queued_diff, o, &regex, NULL, diff_grep);
 
@@ -180,6 +175,18 @@ static int has_changes(mmfile_t *one, mmfile_t *two,
 	return one_contains != two_contains;
 }
 
+static void compile_regex(regex_t *r, const char *s, int cflags)
+{
+	int err;
+	err = regcomp(r, s, cflags);
+	if (err) {
+		char errbuf[1024];
+		regerror(err, r, errbuf, 1024);
+		regfree(r);
+		die("invalid regex: %s", errbuf);
+	}
+}
+
 static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,
 			 regex_t *regexp, kwset_t kws, pickaxe_fn fn)
 {
@@ -236,15 +243,7 @@ static void diffcore_pickaxe_count(struct diff_options *o)
 	kwset_t kws = NULL;
 
 	if (opts & DIFF_PICKAXE_REGEX) {
-		int err;
-		err = regcomp(&regex, needle, REG_EXTENDED | REG_NEWLINE);
-		if (err) {
-			/* The POSIX.2 people are surely sick */
-			char errbuf[1024];
-			regerror(err, &regex, errbuf, 1024);
-			regfree(&regex);
-			die("invalid regex: %s", errbuf);
-		}
+		compile_regex(&regex, needle, REG_EXTENDED | REG_NEWLINE);
 		regexp = &regex;
 	} else {
 		kws = kwsalloc(DIFF_OPT_TST(o, PICKAXE_IGNORE_CASE)

diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index 0d36a3c..7e65095 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -8,17 +8,22 @@
 #include "xdiff-interface.h"
 #include "kwset.h"
 
+struct fn_options {
+	regex_t *regex;
+	kwset_t kws;
+};
+
 typedef int (*pickaxe_fn)(mmfile_t *one, mmfile_t *two,
 			  struct diff_options *o,
-			  regex_t *regexp, kwset_t kws);
+			  struct fn_options *fno);
 
 static void compile_regex(regex_t *r, const char *s, int cflags);
 
 static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,
-			 regex_t *regexp, kwset_t kws, pickaxe_fn fn);
+			 pickaxe_fn fn, struct fn_options *fno);
 
 static void pickaxe(struct diff_queue_struct *q, struct diff_options *o,
-		    regex_t *regexp, kwset_t kws, pickaxe_fn fn)
+		    pickaxe_fn fn, struct fn_options *fno)
 {
 	int i;
 	struct diff_queue_struct outq;
@@ -29,7 +34,7 @@ static void pickaxe(struct diff_queue_struct *q, struct diff_options *o,
 		/* Showing the whole changeset if needle exists */
 		for (i = 0; i < q->nr; i++) {
 			struct diff_filepair *p = q->queue[i];
-			if (pickaxe_match(p, o, regexp, kws, fn))
+			if (pickaxe_match(p, o, fn, fno))
 				return; /* do not munge the queue */
 		}
 
@@ -44,7 +49,7 @@ static void pickaxe(struct diff_queue_struct *q, struct diff_options *o,
 		/* Showing only the filepairs that has the needle */
 		for (i = 0; i < q->nr; i++) {
 			struct diff_filepair *p = q->queue[i];
-			if (pickaxe_match(p, o, regexp, kws, fn))
+			if (pickaxe_match(p, o, fn, fno))
 				diff_q(&outq, p);
 			else
 				diff_free_filepair(p);
@@ -83,7 +88,7 @@ static void diffgrep_consume(void *priv, char *line, unsigned long len)
 
 static int diff_grep(mmfile_t *one, mmfile_t *two,
 		     struct diff_options *o,
-		     regex_t *regexp, kwset_t kws)
+		     struct fn_options *fno)
 {
 	regmatch_t regmatch;
 	struct diffgrep_cb ecbdata;
@@ -91,9 +96,9 @@ static int diff_grep(mmfile_t *one, mmfile_t *two,
 	xdemitconf_t xecfg;
 
 	if (!one)
-		return !regexec(regexp, two->ptr, 1, &regmatch, 0);
+		return !regexec(fno->regex, two->ptr, 1, &regmatch, 0);
 	if (!two)
-		return !regexec(regexp, one->ptr, 1, &regmatch, 0);
+		return !regexec(fno->regex, one->ptr, 1, &regmatch, 0);
 
 	/*
 	 * We have both sides; need to run textual diff and see if
@@ -101,7 +106,7 @@ static int diff_grep(mmfile_t *one, mmfile_t *two,
 	 */
 	memset(&xpp, 0, sizeof(xpp));
 	memset(&xecfg, 0, sizeof(xecfg));
-	ecbdata.regexp = regexp;
+	ecbdata.regexp = fno->regex;
 	ecbdata.hit = 0;
 	xecfg.ctxlen = o->context;
 	xecfg.interhunkctxlen = o->interhunkcontext;
@@ -113,6 +118,7 @@ static int diff_grep(mmfile_t *one, mmfile_t *two,
 static void diffcore_pickaxe_grep(struct diff_options *o)
 {
 	regex_t regex;
+	struct fn_options fno;
 	int cflags = REG_EXTENDED | REG_NEWLINE;
 
 	if (DIFF_OPT_TST(o, PICKAXE_IGNORE_CASE))
@@ -120,13 +126,14 @@ static void diffcore_pickaxe_grep(struct diff_options *o)
 
 	compile_regex(&regex, o->pickaxe, cflags);
 
-	pickaxe(&diff_queued_diff, o, &regex, NULL, diff_grep);
+	fno.regex = &regex;
+	pickaxe(&diff_queued_diff, o, diff_grep, &fno);
 
 	regfree(&regex);
 	return;
 }
 
-static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws)
+static unsigned int contains(mmfile_t *mf, struct fn_options *fno)
 {
 	unsigned int cnt;
 	unsigned long sz;
@@ -136,12 +143,12 @@ static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws)
 	data = mf->ptr;
 	cnt = 0;
 
-	if (regexp) {
+	if (fno->regex) {
 		regmatch_t regmatch;
 		int flags = 0;
 
 		assert(data[sz] == '\0');
-		while (*data && !regexec(regexp, data, 1, &regmatch, flags)) {
+		while (*data && !regexec(fno->regex, data, 1, &regmatch, flags)) {
 			flags |= REG_NOTBOL;
 			data += regmatch.rm_eo;
 			if (*data && regmatch.rm_so == regmatch.rm_eo)
@@ -152,7 +159,7 @@ static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws)
 	} else { /* Classic exact string match */
 		while (sz) {
 			struct kwsmatch kwsm;
-			size_t offset = kwsexec(kws, data, sz, &kwsm);
+			size_t offset = kwsexec(fno->kws, data, sz, &kwsm);
 			const char *found;
 			if (offset == -1)
 				break;
@@ -168,10 +175,10 @@ static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws)
 
 static int has_changes(mmfile_t *one, mmfile_t *two,
 		       struct diff_options *o,
-		       regex_t *regexp, kwset_t kws)
+		       struct fn_options *fno)
 {
-	unsigned int one_contains = one ? contains(one, regexp, kws) : 0;
-	unsigned int two_contains = two ? contains(two, regexp, kws) : 0;
+	unsigned int one_contains = one ? contains(one, fno) : 0;
+	unsigned int two_contains = two ? contains(two, fno) : 0;
 	return one_contains != two_contains;
 }
 
@@ -188,7 +195,7 @@ static void compile_regex(regex_t *r, const char *s, int cflags)
 }
 
 static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,
-			 regex_t *regexp, kwset_t kws, pickaxe_fn fn)
+			 pickaxe_fn fn, struct fn_options *fno)
 {
 	struct userdiff_driver *textconv_one = NULL;
 	struct userdiff_driver *textconv_two = NULL;
@@ -222,7 +229,7 @@ static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,
 
 	ret = fn(DIFF_FILE_VALID(p->one) ? &mf1 : NULL,
 		 DIFF_FILE_VALID(p->two) ? &mf2 : NULL,
-		 o, regexp, kws);
+		 o, fno);
 
 	if (textconv_one)
 		free(mf1.ptr);
@@ -236,6 +243,7 @@ static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,
 
 static void diffcore_pickaxe_count(struct diff_options *o)
 {
+	struct fn_options fno;
 	const char *needle = o->pickaxe;
 	int opts = o->pickaxe_opts;
 	unsigned long len = strlen(needle);
@@ -252,7 +260,9 @@ static void diffcore_pickaxe_count(struct diff_options *o)
 		kwsprep(kws);
 	}
 
-	pickaxe(&diff_queued_diff, o, regexp, kws, has_changes);
+	fno.regex = regexp;
+	fno.kws = kws;
+	pickaxe(&diff_queued_diff, o, has_changes, &fno);
 
 	if (opts & DIFF_PICKAXE_REGEX)
 		regfree(&regex);

diff.c, diff.h

diff --git a/diff.c b/diff.c
index e343191..f978ee7 100644
--- a/diff.c
+++ b/diff.c
@@ -2203,7 +2203,7 @@ int diff_filespec_is_binary(struct diff_filespec *one)
 	return one->is_binary;
 }
 
-static const struct userdiff_funcname *diff_funcname_pattern(struct diff_filespec *one)
+const struct userdiff_funcname *diff_funcname_pattern(struct diff_filespec *one)
 {
 	diff_filespec_load_driver(one);
 	return one->driver->funcname.pattern ? &one->driver->funcname : NULL;
diff --git a/diff.h b/diff.h
index a24a767..9e96fc9 100644
--- a/diff.h
+++ b/diff.h
@@ -349,4 +349,6 @@ extern int print_stat_summary(FILE *fp, int files,
 			      int insertions, int deletions);
 extern void setup_diff_pager(struct diff_options *);
 
+const struct userdiff_funcname *diff_funcname_pattern(struct diff_filespec *);
+
 #endif /* DIFF_H */

diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index 7e65095..103fe6c 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -7,10 +7,12 @@
 #include "diffcore.h"
 #include "xdiff-interface.h"
 #include "kwset.h"
+#include "userdiff.h"
 
 struct fn_options {
 	regex_t *regex;
 	kwset_t kws;
+	const struct userdiff_funcname *funcname_pattern;
 };
 
 typedef int (*pickaxe_fn)(mmfile_t *one, mmfile_t *two,
@@ -224,6 +226,13 @@ static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,
 	if (textconv_one == textconv_two && diff_unmodified_pair(p))
 		return 0;
 
+	const struct userdiff_funcname *funcname_pattern;
+	funcname_pattern = diff_funcname_pattern(p->one);
+	if (!funcname_pattern)
+		funcname_pattern = diff_funcname_pattern(p->two);
+
+	fno->funcname_pattern = funcname_pattern;
+
 	mf1.size = fill_textconv(textconv_one, p->one, &mf1.ptr);
 	mf2.size = fill_textconv(textconv_two, p->two, &mf2.ptr);
 

builtin/log.c, diff.c, diff.h, diffcore-pickaxe.c, revision.c

diff --git a/builtin/log.c b/builtin/log.c
index b97373d..78694de 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -158,7 +158,7 @@ static void cmd_log_init_finish(int argc, const char **argv, const char *prefix,
 	if (rev->show_notes)
 		init_display_notes(&rev->notes_opt);
 
-	if (rev->diffopt.pickaxe || rev->diffopt.filter)
+	if (rev->diffopt.pickaxe || rev->diffopt.filter || rev->diffopt.funcname)
 		rev->always_show_header = 0;
 	if (DIFF_OPT_TST(&rev->diffopt, FOLLOW_RENAMES)) {
 		rev->always_show_header = 0;
diff --git a/diff.c b/diff.c
index f978ee7..2f6dbc1 100644
--- a/diff.c
+++ b/diff.c
@@ -3298,7 +3298,7 @@ void diff_setup_done(struct diff_options *options)
 	/*
 	 * Also pickaxe would not work very well if you do not say recursive
 	 */
-	if (options->pickaxe)
+	if (options->pickaxe || options->funcname)
 		DIFF_OPT_SET(options, RECURSIVE);
 	/*
 	 * When patches are generated, submodules diffed against the work tree
@@ -3821,6 +3821,10 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		options->orderfile = optarg;
 		return argcount;
 	}
+	else if ((argcount = parse_long_opt("function-name", av, &optarg))) {
+		options->funcname = optarg;
+		return argcount;
+	}
 	else if ((argcount = parse_long_opt("diff-filter", av, &optarg))) {
 		int offending = parse_diff_filter_opt(optarg, options);
 		if (offending)
@@ -4768,7 +4772,7 @@ void diffcore_std(struct diff_options *options)
 		if (options->break_opt != -1)
 			diffcore_merge_broken();
 	}
-	if (options->pickaxe)
+	if (options->pickaxe || options->funcname)
 		diffcore_pickaxe(options);
 	if (options->orderfile)
 		diffcore_order(options->orderfile);
diff --git a/diff.h b/diff.h
index 9e96fc9..0fd5f1d 100644
--- a/diff.h
+++ b/diff.h
@@ -107,6 +107,7 @@ enum diff_words_type {
 struct diff_options {
 	const char *orderfile;
 	const char *pickaxe;
+	const char *funcname;
 	const char *single_follow;
 	const char *a_prefix, *b_prefix;
 	unsigned flags;
diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index 103fe6c..259a8fa 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -67,6 +67,12 @@ struct diffgrep_cb {
 	int hit;
 };
 
+struct funcname_cb {
+	struct userdiff_funcname *pattern;
+	regex_t *regex;
+	int hit;
+};
+
 static void diffgrep_consume(void *priv, char *line, unsigned long len)
 {
 	struct diffgrep_cb *data = priv;
@@ -88,6 +94,20 @@ static void diffgrep_consume(void *priv, char *line, unsigned long len)
 	line[len] = hold;
 }
 
+static void match_funcname(void *priv, char *line, unsigned long len)
+{
+	regmatch_t regmatch;
+	int hold;
+	struct funcname_cb *data = priv;
+	hold = line[len];
+	line[len] = '\0';
+
+	if (line[0] == '@' && line[1] == '@')
+		if (!regexec(data->regex, line, 1, &regmatch, 0))
+			data->hit = 1;
+	line[len] = hold;
+}
+
 static int diff_grep(mmfile_t *one, mmfile_t *two,
 		     struct diff_options *o,
 		     struct fn_options *fno)
@@ -117,6 +137,38 @@ static int diff_grep(mmfile_t *one, mmfile_t *two,
 	return ecbdata.hit;
 }
 
+static int diff_funcname_filter(mmfile_t *one, mmfile_t *two,
+				struct diff_options *o,
+				struct fn_options *fno)
+{
+	struct funcname_cb ecbdata;
+	xpparam_t xpp;
+	xdemitconf_t xecfg;
+
+	mmfile_t empty;
+	empty.ptr = "";
+	empty.size = 0;
+	if (!one)
+		one = ∅
+	if (!two)
+		two = ∅
+	memset(&xpp, 0, sizeof(xpp));
+	memset(&xecfg, 0, sizeof(xecfg));
+	ecbdata.regex = fno->regex;
+	ecbdata.hit = 0;
+	xecfg.ctxlen = o->context;
+
+	if (fno->funcname_pattern)
+		xdiff_set_find_func(&xecfg, fno->funcname_pattern->pattern,
+					    fno->funcname_pattern->cflags);
+	xecfg.interhunkctxlen = o->interhunkcontext;
+	if (!(one && two))
+		xecfg.flags = XDL_EMIT_FUNCCONTEXT;
+	xecfg.flags |= XDL_EMIT_FUNCNAMES;
+	xdi_diff_outf(one, two, match_funcname, &ecbdata, &xpp, &xecfg);
+	return ecbdata.hit;
+}
+
 static void diffcore_pickaxe_grep(struct diff_options *o)
 {
 	regex_t regex;
@@ -204,7 +256,7 @@ static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,
 	mmfile_t mf1, mf2;
 	int ret;
 
-	if (!o->pickaxe[0])
+	if (o->pickaxe && !o->pickaxe[0])
 		return 0;
 
 	/* ignore unmerged */
@@ -280,11 +332,24 @@ static void diffcore_pickaxe_count(struct diff_options *o)
 	return;
 }
 
+static void diffcore_funcname(struct diff_options *o)
+{
+	struct fn_options fno;
+	regex_t regex;
+
+	fno.regex = &regex;
+	compile_regex(&regex, o->funcname, REG_EXTENDED | REG_NEWLINE);
+	pickaxe(&diff_queued_diff, o, diff_funcname_filter, &fno);
+	regfree(&regex);
+}
+
 void diffcore_pickaxe(struct diff_options *o)
 {
+	if (o->funcname)
+		diffcore_funcname(o);
 	/* Might want to warn when both S and G are on; I don't care... */
 	if (o->pickaxe_opts & DIFF_PICKAXE_KIND_G)
 		diffcore_pickaxe_grep(o);
-	else
+	else if (o-> pickaxe_opts & DIFF_PICKAXE_KIND_S)
 		diffcore_pickaxe_count(o);
 }
diff --git a/revision.c b/revision.c
index 8508550..d81d9b9 100644
--- a/revision.c
+++ b/revision.c
@@ -2211,8 +2211,9 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
 	if (revs->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT)
 		revs->diff = 1;
 
-	/* Pickaxe, diff-filter and rename following need diffs */
+	/* Pickaxe, funcname, diff-filter and rename following need diffs */
 	if (revs->diffopt.pickaxe ||
+	    revs->diffopt.funcname ||
 	    revs->diffopt.filter ||
 	    DIFF_OPT_TST(&revs->diffopt, FOLLOW_RENAMES))
 		revs->diff = 1;

diff.c, diffcore-pickaxe.c, xdiff/xdiff.h, xdiff/xemit.c

diff --git a/diff.c b/diff.c
index 2f6dbc1..914b4a2 100644
--- a/diff.c
+++ b/diff.c
@@ -2380,6 +2380,8 @@ static void builtin_diff(const char *name_a,
 		xecfg.ctxlen = o->context;
 		xecfg.interhunkctxlen = o->interhunkcontext;
 		xecfg.flags = XDL_EMIT_FUNCNAMES;
+		if (o->funcname)
+			xecfg.flags |= XDL_EMIT_MOREFUNCNAMES;
 		if (DIFF_OPT_TST(o, FUNCCONTEXT))
 			xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
 		if (pe)
diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index 259a8fa..ab31c18 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -164,7 +164,7 @@ static int diff_funcname_filter(mmfile_t *one, mmfile_t *two,
 	xecfg.interhunkctxlen = o->interhunkcontext;
 	if (!(one && two))
 		xecfg.flags = XDL_EMIT_FUNCCONTEXT;
-	xecfg.flags |= XDL_EMIT_FUNCNAMES;
+	xecfg.flags |= XDL_EMIT_FUNCNAMES | XDL_EMIT_MOREFUNCNAMES;
 	xdi_diff_outf(one, two, match_funcname, &ecbdata, &xpp, &xecfg);
 	return ecbdata.hit;
 }
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index c033991..469bded 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -44,6 +44,7 @@
 #define XDL_EMIT_FUNCNAMES (1 << 0)
 #define XDL_EMIT_COMMON (1 << 1)
 #define XDL_EMIT_FUNCCONTEXT (1 << 2)
+#define XDL_EMIT_MOREFUNCNAMES (1 << 3)
 
 #define XDL_MMB_READONLY (1 << 0)
 
diff --git a/xdiff/xemit.c b/xdiff/xemit.c
index 4266ada..0ddb094 100644
--- a/xdiff/xemit.c
+++ b/xdiff/xemit.c
@@ -23,6 +23,10 @@
 #include "xinclude.h"
 
 
+struct func_line {
+	long len;
+	char buf[80];
+};
 
 
 static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec);
@@ -135,12 +139,7 @@ static int xdl_emit_common(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 	return 0;
 }
 
-struct func_line {
-	long len;
-	char buf[80];
-};
-
-static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
+static long get_func_line(xdfile_t *xdf, xdemitconf_t const *xecfg,
 			  struct func_line *func_line, long start, long limit)
 {
 	find_func_t ff = xecfg->find_func ? xecfg->find_func : def_ff;
@@ -150,9 +149,9 @@ static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
 	buf = func_line ? func_line->buf : dummy;
 	size = func_line ? sizeof(func_line->buf) : sizeof(dummy);
 
-	for (l = start; l != limit && 0 <= l && l < xe->xdf1.nrec; l += step) {
+	for (l = start; l != limit && 0 <= l && l < xdf->nrec; l += step) {
 		const char *rec;
-		long reclen = xdl_get_rec(&xe->xdf1, l, &rec);
+		long reclen = xdl_get_rec(xdf, l, &rec);
 		long len = ff(rec, reclen, buf, size, xecfg->find_func_priv);
 		if (len >= 0) {
 			if (func_line)
@@ -167,7 +166,7 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 		  xdemitconf_t const *xecfg) {
 	long s1, s2, e1, e2, lctx;
 	xdchange_t *xch, *xche;
-	long funclineprev = -1;
+	long funclineprev1 = -1, funclineprev2 = -1;
 	struct func_line func_line = { 0 };
 
 	if (xecfg->flags & XDL_EMIT_COMMON)
@@ -182,7 +181,7 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 		s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
 
 		if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
-			long fs1 = get_func_line(xe, xecfg, NULL, xch->i1, -1);
+			long fs1 = get_func_line(&xe->xdf1, xecfg, NULL, xch->i1, -1);
 			if (fs1 < 0)
 				fs1 = 0;
 			if (fs1 < s1) {
@@ -200,7 +199,7 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 		e2 = xche->i2 + xche->chg2 + lctx;
 
 		if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
-			long fe1 = get_func_line(xe, xecfg, NULL,
+			long fe1 = get_func_line(&xe->xdf1, xecfg, NULL,
 						 xche->i1 + xche->chg1,
 						 xe->xdf1.nrec);
 			if (fe1 < 0)
@@ -218,7 +217,7 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 			if (xche->next) {
 				long l = xche->next->i1;
 				if (l <= e1 ||
-				    get_func_line(xe, xecfg, NULL, l, e1) < 0) {
+				    get_func_line(&xe->xdf1, xecfg, NULL, l, e1) < 0) {
 					xche = xche->next;
 					goto again;
 				}
@@ -229,10 +228,18 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 		 * Emit current hunk header.
 		 */
 
-		if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
-			get_func_line(xe, xecfg, &func_line,
-				      s1 - 1, funclineprev);
-			funclineprev = s1 - 1;
+		if (xecfg->flags & XDL_EMIT_MOREFUNCNAMES) {
+			long fl_in_xch1 = get_func_line(&xe->xdf1, xecfg,
+					&func_line, xch->i1, xch->i1+xch->chg1);
+			if (fl_in_xch1 < 0) {
+				get_func_line(&xe->xdf2, xecfg, &func_line,
+					      xch->i2, funclineprev2);
+				funclineprev2 = xch->i2;
+			}
+		} else if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
+			get_func_line(&xe->xdf1, xecfg, &func_line,
+				      s1 - 1, funclineprev1);
+			funclineprev1 = s1 - 1;
 		}
 		if (xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
 				      func_line.buf, func_line.len, ecb) < 0)

diff.c, diffcore-pickaxe.c, xdiff/xdiff.h, xdiff/xdiffi.c, xdiff/xemit.c, xdiff/xemit.h

diff --git a/diff.c b/diff.c
index 914b4a2..a86206c 100644
--- a/diff.c
+++ b/diff.c
@@ -2381,7 +2381,8 @@ static void builtin_diff(const char *name_a,
 		xecfg.interhunkctxlen = o->interhunkcontext;
 		xecfg.flags = XDL_EMIT_FUNCNAMES;
 		if (o->funcname)
-			xecfg.flags |= XDL_EMIT_MOREFUNCNAMES;
+			xecfg.flags |= XDL_EMIT_MOREFUNCNAMES
+				    | XDL_EMIT_MOREHUNKHEADS;
 		if (DIFF_OPT_TST(o, FUNCCONTEXT))
 			xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
 		if (pe)
diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index ab31c18..d9f4c30 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -164,7 +164,8 @@ static int diff_funcname_filter(mmfile_t *one, mmfile_t *two,
 	xecfg.interhunkctxlen = o->interhunkcontext;
 	if (!(one && two))
 		xecfg.flags = XDL_EMIT_FUNCCONTEXT;
-	xecfg.flags |= XDL_EMIT_FUNCNAMES | XDL_EMIT_MOREFUNCNAMES;
+	xecfg.flags |= XDL_EMIT_FUNCNAMES | XDL_EMIT_MOREFUNCNAMES
+		    | XDL_EMIT_MOREHUNKHEADS;
 	xdi_diff_outf(one, two, match_funcname, &ecbdata, &xpp, &xecfg);
 	return ecbdata.hit;
 }
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index 469bded..787c376 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -45,6 +45,7 @@
 #define XDL_EMIT_COMMON (1 << 1)
 #define XDL_EMIT_FUNCCONTEXT (1 << 2)
 #define XDL_EMIT_MOREFUNCNAMES (1 << 3)
+#define XDL_EMIT_MOREHUNKHEADS (1 << 4)
 
 #define XDL_MMB_READONLY (1 << 0)
 
diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c
index 2358a2d..c29804e 100644
--- a/xdiff/xdiffi.c
+++ b/xdiff/xdiffi.c
@@ -545,7 +545,7 @@ static int xdl_call_hunk_func(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 	xdchange_t *xch, *xche;
 
 	for (xch = xscr; xch; xch = xche->next) {
-		xche = xdl_get_hunk(&xch, xecfg);
+		xche = xdl_get_hunk(xe, &xch, xecfg);
 		if (!xch)
 			break;
 		if (xecfg->hunk_func(xch->i1, xche->i1 + xche->chg1 - xch->i1,
diff --git a/xdiff/xemit.c b/xdiff/xemit.c
index 0ddb094..f49eaaf 100644
--- a/xdiff/xemit.c
+++ b/xdiff/xemit.c
@@ -29,6 +29,9 @@ struct func_line {
 };
 
 
+static long get_func_line(xdfile_t *xdf, xdemitconf_t const *xecfg,
+			  struct func_line *func_line, long start, long limit);
+
 static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec);
 static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb);
 
@@ -62,7 +65,7 @@ static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *
  * inside the differential hunk according to the specified configuration.
  * Also advance xscr if the first changes must be discarded.
  */
-xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
+xdchange_t *xdl_get_hunk(xdfenv_t *xe, xdchange_t **xscr, xdemitconf_t const *xecfg)
 {
 	xdchange_t *xch, *xchp, *lxch;
 	long max_common = 2 * xecfg->ctxlen + xecfg->interhunkctxlen;
@@ -83,6 +86,59 @@ xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
 
 	lxch = *xscr;
 
+	if (xecfg->flags & XDL_EMIT_MOREHUNKHEADS)
+		for (xch = *xscr; xch; xch=xch->next) {
+			/*
+			 * If a current change contains a func_line, end this
+			 * hunk immediately before and create a new hunk
+			 * starting from that line.
+			 */
+			long fl_in_xch1 = get_func_line(&xe->xdf1, xecfg, NULL,
+						xch->i1, xch->i1+xch->chg1);
+			long fl_in_xch2 = get_func_line(&xe->xdf2, xecfg, NULL,
+						xch->i2, xch->i2+xch->chg2);
+			if (fl_in_xch1 >= xch->i1 && fl_in_xch2 >= xch->i2) {
+				xdchange_t *new_next =
+					(xdchange_t *)xdl_malloc(sizeof(xdchange_t));
+				new_next->i1 = xch->i1+xch->chg1;
+				new_next->chg1 = 0;
+				new_next->i2 = xch->i2;
+				new_next->chg2 = xch->chg2;
+				new_next->ignore = xch->ignore;
+				new_next->next = xch->next;
+				xch->next = new_next;
+				xch->chg2 = 0;
+				return xch;
+			}
+			if (fl_in_xch1 > xch->i1) {
+				xdchange_t *new_next =
+					(xdchange_t *)xdl_malloc(sizeof(xdchange_t));
+				new_next->i1 = fl_in_xch1;
+				new_next->chg1 = (xch->i1+xch->chg1)-fl_in_xch1;
+				new_next->i2 = xch->i2;
+				new_next->chg2 = xch->chg2;
+				new_next->ignore = xch->ignore;
+				new_next->next = xch->next;
+				xch->next = new_next;
+				xch->chg1 = fl_in_xch1 - xch->i1;
+				xch->chg2 = 0;
+				return xch;
+			}
+			if (fl_in_xch2 > xch->i2) {
+				xdchange_t *new_next =
+					(xdchange_t *)xdl_malloc(sizeof(xdchange_t));
+				new_next->i2 = fl_in_xch2;
+				new_next->chg2 = (xch->i2+xch->chg2)-fl_in_xch2;
+				new_next->i1 = xch->i1+xch->chg1;
+				new_next->chg1 = 0;
+				new_next->ignore = xch->ignore;
+				new_next->next = xch->next;
+				xch->next = new_next;
+				xch->chg2 = fl_in_xch2 - xch->i2;
+				return xch;
+			}
+		}
+
 	for (xchp = *xscr, xch = xchp->next; xch; xchp = xch, xch = xch->next) {
 		long distance = xch->i1 - (xchp->i1 + xchp->chg1);
 		if (distance > max_common)
@@ -173,7 +229,7 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 		return xdl_emit_common(xe, xscr, ecb, xecfg);
 
 	for (xch = xscr; xch; xch = xche->next) {
-		xche = xdl_get_hunk(&xch, xecfg);
+		xche = xdl_get_hunk(xe, &xch, xecfg);
 		if (!xch)
 			break;
 
diff --git a/xdiff/xemit.h b/xdiff/xemit.h
index d297107..4d584f5 100644
--- a/xdiff/xemit.h
+++ b/xdiff/xemit.h
@@ -27,7 +27,9 @@
 typedef int (*emit_func_t)(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 			   xdemitconf_t const *xecfg);
 
-xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg);
+xdchange_t *xdl_get_hunk(xdfenv_t *xe, xdchange_t **xscr,
+			 xdemitconf_t const *xecfg);
+
 int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 		  xdemitconf_t const *xecfg);
 

diff --git a/t/t4213-log-function-name.sh b/t/t4213-log-function-name.sh
new file mode 100755
index 0000000..1243ce5
--- /dev/null
+++ b/t/t4213-log-function-name.sh
@@ -0,0 +1,73 @@
+#!/bin/sh
+
+test_description='log --function-name'
+. ./test-lib.sh
+
+test_expect_success setup '
+	echo "* diff=cpp" > .gitattributes
+
+	>file &&
+	git add file &&
+	test_tick &&
+	git commit -m initial &&
+
+	printf "int main(){\n\treturn 0;\n}\n" >> file &&
+	test_tick &&
+	git commit -am second
+
+	printf "void newfunc(){\n\treturn;\n}\n" >> file &&
+	test_tick &&
+	git commit -am third
+
+	printf "void newfunc2(){\n\treturn;\n}\n" | cat - file > temp &&
+	mv temp file &&
+	test_tick &&
+	git commit -am fourth
+
+	printf "void newfunc3(){\n\treturn;\n}\n" | cat - file > temp &&
+	mv temp file &&
+	test_tick &&
+	git commit -am fifth
+
+	sed -i -e "s/void newfunc2/void newfunc4/" file &&
+	test_tick &&
+	git commit -am sixth
+'
+
+test_expect_success 'log --function-name=main' '
+	git log --function-name=main >actual &&
+	git log --grep=second >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'log --function-name "newfunc\W"' '
+	git log --function-name "newfunc\W" >actual &&
+	git log --grep=third >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'log --function-name "newfunc2"' '
+	git log --function-name newfunc2 >actual &&
+	git log -E --grep "sixth|fourth" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'log --function-name "newfunc3"' '
+	git log --function-name newfunc3 >actual &&
+	git log --grep=fifth >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'log --function-name "newfunc4"' '
+	git log --function-name newfunc4 >actual &&
+	git log --grep=sixth >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'log --function-name "newfunc"' '
+	git log --function-name newfunc >actual &&
+	git log -E --grep "third|fourth|fifth|sixth" >expect &&
+	test_cmp expect actual
+'
+
+test_done

Documentation/diff-options.txt, Documentation/gitdiffcore.txt

diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 9b37b2a..a778dff 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -427,6 +427,15 @@ information.
 --pickaxe-regex::
 	Treat the <string> given to `-S` as an extended POSIX regular
 	expression to match.
+
+--function-name<regex>::
+	Look for differences whose patch text contains hunk headers that match
+	<regex>. This can be useful to locate changes to a particular function
+	or other semantic element in a program, since hunk headers are intended
+	to indicate the "function context" (in the sense of
+	`--function-context`) in which the particular change occurs. The
+	function context is determined by the diff driver corresponding to the
+	file in question; see linkgit:gitattributes[7] for details.
 endif::git-format-patch[]
 
 -O<orderfile>::
diff --git a/Documentation/gitdiffcore.txt b/Documentation/gitdiffcore.txt
index c8b3e51..b8477ce 100644
--- a/Documentation/gitdiffcore.txt
+++ b/Documentation/gitdiffcore.txt
@@ -222,10 +222,11 @@ version prefixed with '+'.
 diffcore-pickaxe: For Detecting Addition/Deletion of Specified String
 ---------------------------------------------------------------------
 
-This transformation limits the set of filepairs to those that change
+This transformation limits the set of filepairs to those that involve
 specified strings between the preimage and the postimage in a certain
-way.  -S<block of text> and -G<regular expression> options are used to
-specify different ways these strings are sought.
+way.  -S<block of text>, -G<regular expression>, and
+--function-name<regular expression> options are used to specify
+different ways these strings are sought.
 
 "-S<block of text>" detects filepairs whose preimage and postimage
 have different number of occurrences of the specified block of text.
@@ -251,6 +252,16 @@ criterion in a changeset, the entire changeset is kept.  This behavior
 is designed to make reviewing changes in the context of the whole
 changeset easier.
 
+"--function-name<regular expression>" detects filepairs whose textual
+diff contains a hunk header that matches the given regular expression.
+The hunk header is generated via the diff driver specified in
+`.gitattributes`, and is intended to reflect the "function context"
+(in the sense of `--function-context`) in which the change occurs,
+with programming-language-dependent heuristics. As of now, the
+programming language is not auto-detected in any way. Also note that
+hunks whose headers do not match the regular expression are not
+currently filtered out; this is only a filepair filter.
+
 diffcore-order: For Sorting the Output Based on Filenames
 ---------------------------------------------------------