Don't prevent ',' from getting escaped in theindex.html

- Enable escaping of links in theindex.html
- Fixes https://github.com/nim-lang/Nim/issues/9107.
- Second part of the fix for https://github.com/nim-lang/Nim/issues/9097.

lib/packages/docutils/rstgen.nim

@@ -424,11 +424,15 @@ proc sortIndex(a: var openArray[IndexEntry]) =
     if h == 1: break
 
 proc escapeLink(s: string): string =
+  ## This proc is mostly copied from uri/encodeUrl except that
+  ## these chars are also left unencoded: '#', '/'.
   result = newStringOfCap(s.len + s.len shr 2)
   for c in items(s):
     case c
-    of 'a'..'z', '_', 'A'..'Z', '0'..'9', '.', '#', ',', '/':
-      result.add c
+    of 'a'..'z', 'A'..'Z', '0'..'9', '-', '.', '_', '~': # same as that in uri/encodeUrl
+      add(result, c)
+    of '#', '/': # example.com/foo/#bar (don't escape the '/' and '#' in such links)
+      add(result, c)
     else:
       add(result, "%")
       add(result, toHex(ord(c), 2))
@@ -444,7 +448,7 @@ proc generateSymbolIndex(symbols: seq[IndexEntry]): string =
     var j = i
     while j < symbols.len and keyword == symbols[j].keyword:
       let
-        url = symbols[j].link #.escapeLink
+        url = symbols[j].link.escapeLink
         text = if symbols[j].linkTitle.len > 0: symbols[j].linkTitle else: url
         desc = if symbols[j].linkDesc.len > 0: symbols[j].linkDesc else: ""
       if desc.len > 0:

lib/pure/uri.nim

@@ -60,6 +60,7 @@ proc encodeUrl*(s: string, usePlus=true): string =
   let fromSpace = if usePlus: "+" else: "%20"
   for c in s:
     case c
+    # https://tools.ietf.org/html/rfc3986#section-2.3
     of 'a'..'z', 'A'..'Z', '0'..'9', '-', '.', '_', '~': add(result, c)
     of ' ': add(result, fromSpace)
     else:

nimdoc/testproject/expected/theindex.html

@@ -1227,9 +1227,9 @@ function main() {
           </ul></dd>
 <dt><a name="bar" href="#bar"><span>bar:</span></a></dt><dd><ul class="simple">
 <li><a class="reference external"
-          data-doc-search-tag="testproject: bar[T](a, b: T): T" href="testproject.html#bar,T,T">testproject: bar[T](a, b: T): T</a></li>
+          data-doc-search-tag="testproject: bar[T](a, b: T): T" href="testproject.html#bar%2CT%2CT">testproject: bar[T](a, b: T): T</a></li>
           <li><a class="reference external"
-          data-doc-search-tag="testproject: bar(): untyped" href="testproject.html#bar.m,">testproject: bar(): untyped</a></li>
+          data-doc-search-tag="testproject: bar(): untyped" href="testproject.html#bar.m%2C">testproject: bar(): untyped</a></li>
           </ul></dd>
 <dt><a name="enumValueA" href="#enumValueA"><span>enumValueA:</span></a></dt><dd><ul class="simple">
 <li><a class="reference external"
@@ -1245,7 +1245,7 @@ function main() {
           </ul></dd>
 <dt><a name="foo" href="#foo"><span>foo:</span></a></dt><dd><ul class="simple">
 <li><a class="reference external"
-          data-doc-search-tag="testproject: foo(a, b: SomeType)" href="testproject.html#foo.t,SomeType,SomeType">testproject: foo(a, b: SomeType)</a></li>
+          data-doc-search-tag="testproject: foo(a, b: SomeType)" href="testproject.html#foo.t%2CSomeType%2CSomeType">testproject: foo(a, b: SomeType)</a></li>
           </ul></dd>
 <dt><a name="SomeType" href="#SomeType"><span>SomeType:</span></a></dt><dd><ul class="simple">
 <li><a class="reference external"
@@ -1253,7 +1253,7 @@ function main() {
           </ul></dd>
 <dt><a name="someType" href="#someType"><span>someType:</span></a></dt><dd><ul class="simple">
 <li><a class="reference external"
-          data-doc-search-tag="utils: someType(): SomeType" href="subdir/subdir_b/utils.html#someType,">utils: someType(): SomeType</a></li>
+          data-doc-search-tag="utils: someType(): SomeType" href="subdir/subdir_b/utils.html#someType%2C">utils: someType(): SomeType</a></li>
           </ul></dd>
 </dl>
     <div class="row">