From 0aceca8673c1d9a8bc34faa460389768efa08eb7 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Tue, 1 Nov 2022 14:18:00 +0000
Subject: make: comments in macro expansions and command lines

The POSIX specification says:

   There are three kinds of comments:  blank lines, empty lines, and
   a <number-sign> ('#') and all following characters up to the first
   unescaped <newline> character.

Most implementations don't treat '#' in a macro expansion or a command
line as the start of a comment.  POSIX doesn't mention either of these
exceptions.

Permit the exceptions as a non-POSIX extension.
---
 miscutils/make.c     | 19 ++++++++++++++++---
 testsuite/make.tests | 18 ++++++++++++++++++
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/miscutils/make.c b/miscutils/make.c
index 111ab2914..daad75f5c 100644
--- a/miscutils/make.c
+++ b/miscutils/make.c
@@ -1120,7 +1120,11 @@ process_line(char *s)
 	r = s;
 
 	// Strip comment
-	t = strchr(s, '#');
+	// don't treat '#' in macro expansion as a comment
+	if (!posix)
+		t = find_char(s, '#');
+	else
+		t = strchr(s, '#');
 	if (t)
 		*t = '\0';
 
@@ -1401,9 +1405,18 @@ static char *
 process_command(char *s)
 {
 	char *t, *u;
-	int len = strlen(s) + 1;
-	char *outside = xzalloc(len);
+	int len;
+	char *outside;
+
+	if (posix) {
+		// POSIX strips comments from command lines
+		t = strchr(s, '#');
+		if (t)
+			*t = '\0';
+	}
 
+	len = strlen(s) + 1;
+	outside = xzalloc(len);
 	for (t = skip_macro(s); *t; t = skip_macro(t + 1)) {
 		outside[t - s] = 1;
 	}
diff --git a/testsuite/make.tests b/testsuite/make.tests
index a0ca9778b..f52770438 100755
--- a/testsuite/make.tests
+++ b/testsuite/make.tests
@@ -379,6 +379,24 @@ t1? t2* t3[abc]: s1? s2* s3[abc]
 '
 cd .. || exit 1; rm -rf make.tempdir 2>/dev/null
 
+# A '#' character in a macro expansion doesn't start a comment
+testing "make hash in macro expansion isn't a comment" \
+	"make -f -" \
+	": hash # hash\n" "" '
+HASH = hash
+hash = $(HASH:hash=#)
+target:
+	: hash $(hash) hash
+'
+
+# A '#' character in a command line doesn't start a comment
+testing "make hash in command line isn't a comment" \
+	"make -f -" \
+	": hash # hash\n" "" '
+target:
+	: hash # hash
+'
+
 # Skip duplicate entries in $? and $^
 mkdir make.tempdir && cd make.tempdir || exit 1
 touch -t 202206171200 file1 file3
-- 
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