keep trailing tab before a soft line break

api_test/main.c

@@ -526,6 +526,13 @@ static void test_content(test_batch_runner *runner, cmark_node_type type,
 static void parser(test_batch_runner *runner) {
   test_md_to_html(runner, "No newline", "<p>No newline</p>\n",
                   "document without trailing newline");
+
+  // Only spaces are removed before a soft line break; a trailing tab is
+  // kept, matching the spec (which strips only end-of-line spaces).
+  test_md_to_html(runner, "foo\t\nbar\n", "<p>foo\t\nbar</p>\n",
+                  "trailing tab kept before soft line break");
+  test_md_to_html(runner, "foo \nbar\n", "<p>foo\nbar</p>\n",
+                  "trailing space removed before soft line break");
 }
 
 static void render_html(test_batch_runner *runner) {

src/inlines.c

@@ -1399,9 +1399,12 @@ static int parse_inline(subject *subj, cmark_node *parent, int options) {
     startpos = subj->pos;
     subj->pos = endpos;
 
-    // if we're at a newline, strip trailing spaces.
+    // if we're at a newline, strip trailing spaces.  Only spaces are
+    // removed before a line ending; trailing tabs are preserved, as the
+    // spec strips only spaces at the end of a line (a final tab is kept).
     if (S_is_line_end_char(peek_char(subj))) {
-      cmark_chunk_rtrim(&contents);
+      while (contents.len > 0 && contents.data[contents.len - 1] == ' ')
+        contents.len--;
     }
 
     new_inl = make_str(subj, startpos, endpos - 1, contents);