Make self-closing tags errors

README.md

@@ -96,6 +96,10 @@ See [voidtags.c](src/main/c/rule/tag/voidtags.c) for the list of tags considered
 
 This includes tags that close automatically because of siblings (e.g. `<li><li>`), as it greatly simplifies the complexity of the minifier due to guarantees about the structure.
 
+#### `HBE_PARSE_SELF_CLOSING_TAG`
+
+It's an error if a tag is self-closed. Valid in XML, not in HTML.
+
 #### `HBE_PARSE_UNEXPECTED_END` and `HBE_PARSE_EXPECTED_NOT_FOUND`
 
 General syntax errors.

src/main/c/error/error.c

@@ -42,6 +42,7 @@ typedef enum hbe_errcode {
   HBE_PARSE_UNQUOTED_ATTR,
   HBE_PARSE_ILLEGAL_CHILD,
   HBE_PARSE_UNCLOSED_TAG,
+  HBE_PARSE_SELF_CLOSING_TAG,
 
   HBE_PARSE_UNEXPECTED_END,
   HBE_PARSE_EXPECTED_NOT_FOUND,

src/main/c/main.c

@@ -100,6 +100,8 @@ static void _parse_and_add_errors_to_suppress(nh_set_int32_t suppressed_errors,
       nh_set_int32_add(suppressed_errors, HBE_PARSE_UCASE_TAG);
     } else if (hbu_buffer_compare_lit(part, "UNQUOTED_ATTR") == 0) {
       nh_set_int32_add(suppressed_errors, HBE_PARSE_UNQUOTED_ATTR);
+    } else if (hbu_buffer_compare_lit(part, "SELF_CLOSING_TAG") == 0) {
+      nh_set_int32_add(suppressed_errors, HBE_PARSE_SELF_CLOSING_TAG);
     } else {
       hbe_fatal(HBE_CLI_INVALID_SUPPRESSABLE_ERROR, "Unrecognised suppressable error `%s`", hbu_buffer_underlying(part));
     }
@@ -125,11 +127,11 @@ int main(int argc, char **argv) {
       {"verbose", no_argument, NULL, 'v'},
       {"input", required_argument, NULL, 'i'},
       {"output", required_argument, NULL, 'o'},
-      {"suppress", optional_argument, NULL, 's'},
+      {"suppress", required_argument, NULL, 's'},
 
-      {"MXcollapseWhitespace", optional_argument, NULL, 1},
-      {"MXdestroyWholeWhitespace", optional_argument, NULL, 2},
-      {"MXtrimWhitespace", optional_argument, NULL, 3},
+      {"MXcollapseWhitespace", required_argument, NULL, 1},
+      {"MXdestroyWholeWhitespace", required_argument, NULL, 2},
+      {"MXtrimWhitespace", required_argument, NULL, 3},
 
       {"MXtrimClassAttr", no_argument, &(config_stream->trim_class_attr), 0},
       {"MXdecEnt", no_argument, &(config_stream->decode_entities), 0},

src/main/c/stream/tag.c

@@ -33,7 +33,10 @@ void hbs_tag(hbs_options_t so, hbu_pipe_t pipe) {
     }
 
     if (hbu_pipe_accept_if_matches(pipe, "/>")) {
-      hbu_pipe_warn(pipe, "Self-closing tag");
+      if (!hbs_options_supressed_error(so, HBE_PARSE_SELF_CLOSING_TAG)) {
+        hbu_pipe_error(pipe, HBE_PARSE_SELF_CLOSING_TAG, "Self-closing tag");
+        // Unreachable
+      }
       self_closing = 1;
       break;
     }