Fix regression in parsing nested wikilinks in file captions

This regression seems more severe than the bug the commit was
attempting to fix (incorrect parsing of nested wikilinks in normal
links), so that bug is reintroduced until localization-aware parsing
that allows us to detect file links is added.

This commit partially reverts fac60dee48.

CHANGELOG

@@ -1,7 +1,10 @@
-v0.7 (unreleased):
+v0.6.4 (unreleased):
 
 - Dropped support for end-of-life Python 3.5.
 - Added support for Python 3.10. (#278)
+- Fixed a regression in v0.6.2 that broke parsing of nested wikilinks in file
+  captions. For now, the parser will interpret nested wikilinks in normal links
+  as well, even though this differs from MediaWiki. (#270)
 
 v0.6.3 (released September 2, 2021):
 

docs/changelog.rst

@@ -1,14 +1,19 @@
 Changelog
 =========
 
-v0.7
+v0.6.4
+------
 
 Unreleased
 (`changes <https://github.com/earwig/mwparserfromhell/compare/v0.6.3...develop>`__):
 
+- Dropped support for end-of-life Python 3.5.
 - Added support for Python 3.10.
   (`#278 <https://github.com/earwig/mwparserfromhell/issues/278>`_)
+- Fixed a regression in v0.6.2 that broke parsing of nested wikilinks in file
+  captions. For now, the parser will handle interpret wikilinks in normal links
+  as well, even though this differs from MediaWiki.
+  (`#270 <https://github.com/earwig/mwparserfromhell/issues/270>`_)
 
 v0.6.3
 ------

src/mwparserfromhell/parser/ctokenizer/tok_parse.c

@@ -51,7 +51,8 @@ static int Tokenizer_parse_tag(Tokenizer *);
 /*
     Determine whether the given code point is a marker.
 */
-static int is_marker(Py_UCS4 this)
+static int
+is_marker(Py_UCS4 this)
 {
     int i;
 
@@ -2929,9 +2930,10 @@ Tokenizer_parse(Tokenizer *self, uint64_t context, int push)
                 return NULL;
             }
         } else if (this == next && next == '[' && Tokenizer_CAN_RECURSE(self)) {
-            if (this_context & LC_WIKILINK_TEXT) {
-                return Tokenizer_fail_route(self);
-            }
+            // TODO: Only do this if not in a file context:
+            // if (this_context & LC_WIKILINK_TEXT) {
+            //     return Tokenizer_fail_route(self);
+            // }
             if (!(this_context & AGG_NO_WIKILINKS)) {
                 if (Tokenizer_parse_wikilink(self)) {
                     return NULL;

src/mwparserfromhell/parser/tokenizer.py

@@ -1406,8 +1406,9 @@ class Tokenizer:
                     return self._handle_argument_end()
                 self._emit_text("}")
             elif this == nxt == "[" and self._can_recurse():
-                if self._context & contexts.WIKILINK_TEXT:
-                    self._fail_route()
+                # TODO: Only do this if not in a file context:
+                # if self._context & contexts.WIKILINK_TEXT:
+                #     self._fail_route()
                 if not self._context & contexts.NO_WIKILINKS:
                     self._parse_wikilink()
                 else:

tests/tokenizer/wikilinks.mwtest

@@ -54,6 +54,20 @@ output: [WikilinkOpen(), Text(text="foo"), WikilinkSeparator(), Text(text="bar[b
 
 ---
 
+name:   nested
+label:  a wikilink nested within another
+input:  "[[file:foo|[[bar]]]]"
+output: [WikilinkOpen(), Text(text="file:foo"), WikilinkSeparator(), WikilinkOpen(), Text(text="bar"), WikilinkClose(), WikilinkClose()]
+
+---
+
+name:   nested_padding
+label:  a wikilink nested within another, separated by other data
+input:  "[[file:foo|a[[b]]c]]"
+output: [WikilinkOpen(), Text(text="file:foo"), WikilinkSeparator(), Text(text="a"), WikilinkOpen(), Text(text="b"), WikilinkClose(), Text(text="c"), WikilinkClose()]
+
+---
+
 name:   invalid_newline
 label:  invalid wikilink: newline as only content
 input:  "[[\n]]"
@@ -89,20 +103,6 @@ output: [Text(text="[[foo[bar]]")]
 
 ---
 
-name:   invalid_nested_text
-label:  invalid wikilink: nested within the text of another
-input:  "[[foo|[[bar]]]]"
-output: [Text(text="[[foo|"), WikilinkOpen(), Text(text="bar"), WikilinkClose(), Text(text="]]")]
-
-
-name:   invalid_nested_text_2
-label:  invalid wikilink: a wikilink nested within the text of another, with additional content
-input:  "[[foo|a[[b]]c]]"
-output: [Text(text="[[foo|a"), WikilinkOpen(), Text(text="b"), WikilinkClose(), Text(text="c]]")]
-
-
 name:   invalid_nested_title
 label:  invalid wikilink: nested within the title of another
 input:  "[[foo[[bar]]]]"