Rollback all, then redo all, when fixing out-of-order tags; not one-by-one

Imagine the following wikitext:

  <ref name=r/>
  <references>
  <ref name=r>A</ref>
  <ref name=r>B</ref>
  </references>

This is simple. Cite would see these as the following operations, in
order:

1. Use only:       <ref name=r/>
2. References block
3. Define only:    <ref name=r>A</ref>
4. Define only:    <ref name=r>B</ref>

<ref name=r> is defined twice with different content and we get an
error message.

Now, imagine the following wikitext:

  <ref name=r/>
  {{#tag:references|
  <ref name=r>A</ref>
  <ref name=r>B</ref>
  }}

Cite would see these as the following operations, in order:
1. Use only:       <ref name=r/>
2. Use and define: <ref name=r>A</ref>
3. Use and define: <ref name=r>B</ref>
4. References block

When the 'references' block appears, Cite notices that the tag has
parsed content, and deduces that it was called with #tag. We need to
undo the last operations to update internal bookkeeping, as the last
two 'ref' tags do not actually represent ref usages, as we assumed,
but only definitions.

5. Undo:          <ref name=r> reused
6. Define only:   <ref name=r>B</ref>
7. Undo:          <ref name=r> defined
(Right now, it appears to Cite that <ref name=r> was never defined!)
8. Define only: <ref name=r>A</ref>

Thus we get no errors, although we should.

This patch changes the order of the rollback operations:

5. Undo:          <ref name=r> reused
6. Undo:          <ref name=r> defined
7. Define only:   <ref name=r>A</ref>
8. Define only:   <ref name=r>B</ref>

Aha! <ref name=r> is defined twice with different content! We get an
error correctly.

Bug: T124227
Change-Id: I61766c4104856323987cca9a5e4ff85a76b3618b

Cite_body.php

@@ -604,30 +604,39 @@ class Cite {
 		if ( strval( $str ) !== '' ) {
 			$this->mReferencesGroup = $group;
 
-			# Detect whether we were sent already rendered <ref>s
-			# Mostly a side effect of using #tag to call references
+			# Detect whether we were sent already rendered <ref>s.
+			# Mostly a side effect of using #tag to call references.
+			# The following assumes that the parsed <ref>s sent within
+			# the <references> block were the most recent calls to
+			# <ref>.  This assumption is true for all known use cases,
+			# but not strictly enforced by the parser.  It is possible
+			# that some unusual combination of #tag, <references> and
+			# conditional parser functions could be created that would
+			# lead to malformed references here.
 			$count = substr_count( $str, Parser::MARKER_PREFIX . "-ref-" );
+			$redoStack = array();
+
+			# Undo effects of calling <ref> while unaware of containing <references>
 			for ( $i = 1; $i <= $count; $i++ ) {
 				if ( !$this->mRefCallStack ) {
 					break;
 				}
 
-				# The following assumes that the parsed <ref>s sent within
-				# the <references> block were the most recent calls to
-				# <ref>.  This assumption is true for all known use cases,
-				# but not strictly enforced by the parser.  It is possible
-				# that some unusual combination of #tag, <references> and
-				# conditional parser functions could be created that would
-				# lead to malformed references here.
 				$call = array_pop( $this->mRefCallStack );
+				$redoStack[] = $call;
 				if ( $call !== false ) {
 					list( $type, $ref_argv, $ref_str,
 						$ref_key, $ref_group, $ref_index ) = $call;
-
-					# Undo effects of calling <ref> while unaware of containing <references>
 					$this->rollbackRef( $type, $ref_key, $ref_group, $ref_index );
+				}
+			}
 
-					# Rerun <ref> call now that mInReferences is set.
+			# Rerun <ref> call now that mInReferences is set.
+			for ( $i = count( $redoStack ) - 1; $i >= 0; $i-- ) {
+				$call = $redoStack[$i];
+				if ( $call !== false ) {
+					list( $type, $ref_argv, $ref_str,
+						$ref_key, $ref_group, $ref_index ) = $call;
 					$this->guardedRef( $ref_str, $ref_argv, $parser );
 				}
 			}

citeParserTests.txt

@@ -584,3 +584,21 @@ Multiple definition (mixed outside/inside)
 </ol>
 
 !! end
+
+!! test
+Multiple definition (inside {{#tag:references}})
+!! input
+<ref name=a />
+{{#tag:references|
+<ref name=a>abc</ref>
+<ref name=a>def</ref>
+}}
+!! result
+<p><sup id="cite_ref-a_1-0" class="reference"><a href="#cite_note-a-1">[1]</a></sup>
+</p>
+<ol class="references">
+<li id="cite_note-a-1"><span class="mw-cite-backlink"><a href="#cite_ref-a_1-0">↑</a></span> <span class="reference-text">abc <strong class="error mw-ext-cite-error">Cite error: Invalid <code>&lt;ref&gt;</code> tag; name "a" defined multiple times with different content</strong></span>
+</li>
+</ol>
+
+!! end