Re: Some PRETTY FORMATS format:<string> options don't work with git-archive export-subst $Format:$

[Jeff King <peff@peff.net>]

On Thu, Oct 09, 2014 at 12:42:39PM -0500, Derek Moore wrote:

> As far as I've tested it would seem only %N doesn't resolve inside of
> $Format:$, until I maybe do unit tests for this to identify any
> others.

Yes, %N is somewhat special in that the calling code needs to initialize
the notes tree itself. We can't just do it lazily when we see the first
%N because _which_ notes we show depends on other options (e.g., for
log, if you've used --notes-ref, --show-notes=..., etc).

So in theory you need something like 5b16360 (pretty: Initialize notes
if %N is used, 2010-04-13), but adapted for git-archive. The trick,
though, is that we do not even see the format string until we are
looking at a particular file with a $Format$ marker. So you'd have to
lazily initialize notes there (and if you want to support picking
specific notes refs, you'd have to teach git-archive new options to do
so[1]).

Here's a quick-and-dirty patch that makes the snippet you posted earlier
do what I think you expected. I haven't tested it beyond that, and am
not planning to push it forward myself, but please feel free to use it
as a basis for building a solution.

---
diff --git a/archive.c b/archive.c
index 952a659..3af781e 100644
--- a/archive.c
+++ b/archive.c
@@ -5,6 +5,7 @@
 #include "archive.h"
 #include "parse-options.h"
 #include "unpack-trees.h"
+#include "notes.h"
 
 static char const * const archive_usage[] = {
 	N_("git archive [options] <tree-ish> [<path>...]"),
@@ -38,6 +39,8 @@ static void format_subst(const struct commit *commit,
 	if (src == buf->buf)
 		to_free = strbuf_detach(buf, NULL);
 	for (;;) {
+		struct userformat_want ufw = {0};
+		struct strbuf notes = STRBUF_INIT;
 		const char *b, *c;
 
 		b = memmem(src, len, "$Format:", 8);
@@ -50,10 +53,31 @@ static void format_subst(const struct commit *commit,
 		strbuf_reset(&fmt);
 		strbuf_add(&fmt, b + 8, c - b - 8);
 
+		userformat_find_requirements(fmt.buf, &ufw);
+		if (ufw.notes) {
+			static int initialized;
+			if (!initialized) {
+				init_display_notes(NULL);
+				initialized = 1;
+			}
+			format_display_notes(commit->object.sha1, &notes,
+					     get_log_output_encoding(), 1);
+			/*
+			 * trim trailing newlines from note content, which is
+			 * probably more appropriate for $Format$; should
+			 * this actually remove internal newlines, too?
+			 */
+			strbuf_rtrim(&notes);
+		}
+		ctx.notes_message = notes.buf;
+
 		strbuf_add(buf, src, b - src);
 		format_commit_message(commit, fmt.buf, buf, &ctx);
 		len -= c + 1 - src;
 		src  = c + 1;
+
+		ctx.notes_message = NULL;
+		strbuf_release(&notes);
 	}
 	strbuf_add(buf, src, len);
 	strbuf_release(&fmt);

-Peff

[1] I think you could get pretty far using `git -c core.notesRef=foo` to
    give ad-hoc config, as the notes code should use that as the
    ultimate default. But I didn't try it.