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.

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