Disallow links in section headers

This is quite straightforward to implement, since we already had a
function `docToHtmlNoAnchors` (which we used to generate the link in the
sidebar "Contents").

This breaks test `Bug387`, but that test case has aged badly: we now
automatically generate anchors for all headings, so manually adding an
anchor in a section makes no sense. Nested anchors are, as pointed out
in #1054, disallowed by the HTML standard.

Fixes #1054

4 files changed, 19 insertions, 54 deletions

diff --git a/haddock-api/src/Haddock/Backends/Xhtml.hs b/haddock-api/src/Haddock/Backends/Xhtml.hs
index d30312b7..e3d4e8ca 100644
--- a/haddock-api/src/Haddock/Backends/Xhtml.hs
+++ b/haddock-api/src/Haddock/Backends/Xhtml.hs
@@ -681,7 +681,7 @@ processExport :: Bool -> LinksInfo -> Bool -> Maybe Package -> Qualification
               -> ExportItem DocNameI -> Maybe Html
 processExport _ _ _ _ _ ExportDecl { expItemDecl = L _ (InstD {}) } = Nothing -- Hide empty instances
 processExport summary _ _ pkg qual (ExportGroup lev id0 doc)
-  = nothingIf summary $ groupHeading lev id0 << docToHtml (Just id0) pkg qual (mkMeta doc)
+  = nothingIf summary $ groupHeading lev id0 << docToHtmlNoAnchors (Just id0) pkg qual (mkMeta doc)
 processExport summary links unicode pkg qual (ExportDecl decl pats doc subdocs insts fixities splice)
   = processDecl summary $ ppDecl summary links decl pats doc insts fixities subdocs splice unicode pkg qual
 processExport summary _ _ _ qual (ExportNoDecl y [])
diff --git a/html-test/ref/Bug387.html b/html-test/ref/Bug1054.html
index 12887a83..df3fae0a 100644
--- a/html-test/ref/Bug387.html
+++ b/html-test/ref/Bug1054.html
@@ -3,7 +3,7 @@
   ><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"
      /><meta name="viewport" content="width=device-width, initial-scale=1"
      /><title
-    >Bug387</title
+    >Bug1054</title
     ><link href="#" rel="stylesheet" type="text/css" title="Linuwial"
      /><link rel="stylesheet" type="text/css" href="#"
      /><link rel="stylesheet" type="text/css" href="#"
@@ -40,7 +40,7 @@
 	    ></tr
 	  ></table
 	><p class="caption"
-	>Bug387</p
+	>Bug1054</p
 	></div
       ><div id="table-of-contents"
       ><div id="contents-list"
@@ -49,11 +49,9 @@
 	  ><ul
 	  ><li
 	    ><a href="#"
-	      >Section1</a
-	      ></li
-	    ><li
-	    ><a href="#"
-	      >Section2</a
+	      >Header with <code
+		>foo</code
+		> link</a
 	      ></li
 	    ></ul
 	  ></div
@@ -65,49 +63,23 @@
 	  ><ul class="details-toggle" data-details-id="syn"
 	  ><li class="src short"
 	    ><a href="#"
-	      >test1</a
-	      > :: <a href="#" title="Data.Int"
-	      >Int</a
-	      ></li
-	    ><li class="src short"
-	    ><a href="#"
-	      >test2</a
-	      > :: <a href="#" title="Data.Int"
-	      >Int</a
-	      ></li
+	      >foo</a
+	      > :: ()</li
 	    ></ul
 	  ></details
 	></div
       ><div id="interface"
       ><a href="#" id="g:1"
 	><h1
-	  >Section1<a id="a:section1"
-	    ></a
-	    ></h1
-	  ></a
-	><div class="top"
-	><p class="src"
-	  ><a id="v:test1" class="def"
-	    >test1</a
-	    > :: <a href="#" title="Data.Int"
-	    >Int</a
-	    > <a href="#" class="selflink"
-	    >#</a
-	    ></p
-	  ></div
-	><a href="#" id="g:2"
-	><h1
-	  >Section2<a id="a:section2"
-	    ></a
-	    ></h1
+	  >Header with <code
+	    >foo</code
+	    > link</h1
 	  ></a
 	><div class="top"
 	><p class="src"
-	  ><a id="v:test2" class="def"
-	    >test2</a
-	    > :: <a href="#" title="Data.Int"
-	    >Int</a
-	    > <a href="#" class="selflink"
+	  ><a id="v:foo" class="def"
+	    >foo</a
+	    > :: () <a href="#" class="selflink"
 	    >#</a
 	    ></p
 	  ></div
diff --git a/html-test/src/Bug1054.hs b/html-test/src/Bug1054.hs
new file mode 100644
index 00000000..c699f1fb
--- /dev/null
+++ b/html-test/src/Bug1054.hs
@@ -0,0 +1,5 @@
+module Bug1054 where
+
+-- * Header with 'foo' link
+
+foo = ()
diff --git a/html-test/src/Bug387.hs b/html-test/src/Bug387.hs
deleted file mode 100644
index d9fed34e..00000000
--- a/html-test/src/Bug387.hs
+++ /dev/null
@@ -1,12 +0,0 @@
-module Bug387
-  ( -- * Section1#a:section1#
-    test1
-    -- * Section2#a:section2#
-  , test2
-  ) where
-
-test1 :: Int
-test1 = 223
-
-test2 :: Int
-test2 = 42