Add new _getName to get extension decl names for core module docs (#7985)

Fixes #7479

This adds a new variant of `_getName(ExtensionDecl* decl)` to our
markdown doc writer that takes an ExtensionDecl* and returns the name in
the format `extension <name> : <interface>`.

This is required to display "extension T : ITexelElement" properly in
the core module docs, as the existing `_getName(Decl* decl)` returns an
empty string because the name does not come from the `decl` itself, but
rather its `targetType`.

The target type alone is not enough, as that would return `T`, which
will be erroneously interpreted as the name for the generic parameter,
and the doc system will link every mention of `T` to the extension's
page.

ReadTheDocs already displays the name correctly in the TOC of the docs
there, but that is because it falls back to the page title when the name
in the TOC is empty.

---------

Co-authored-by: slangbot <ellieh+slangbot@nvidia.com>
Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>

2 files changed, 38 insertions, 0 deletions

diff --git a/source/slang/slang-doc-markdown-writer.cpp b/source/slang/slang-doc-markdown-writer.cpp
index 2a9a83361..2a215d6bd 100644
--- a/source/slang/slang-doc-markdown-writer.cpp
+++ b/source/slang/slang-doc-markdown-writer.cpp
@@ -356,6 +356,35 @@ String DocMarkdownWriter::_getName(InheritanceDecl* decl)
     return buf.produceString();
 }
 
+String DocMarkdownWriter::_getName(ExtensionDecl* extDecl)
+{
+    StringBuilder buf;
+    buf.clear();
+
+    if (auto declRef = isDeclRefTypeOf<Decl>(extDecl->targetType))
+    {
+        buf << "extension " << _getName(declRef.getDecl()).getUnownedSlice();
+
+        List<InheritanceDecl*> inheritanceDecls;
+        _getDecls(extDecl, inheritanceDecls);
+
+        const Index count = inheritanceDecls.getCount();
+        if (count)
+        {
+            buf << " : ";
+
+            List<String> baseNames;
+            for (Index i = 0; i < count; ++i)
+            {
+                baseNames.add(_getName(inheritanceDecls[i]));
+            }
+            StringUtil::join(baseNames, UnownedStringSlice(", "), buf);
+        }
+    }
+
+    return buf.produceString();
+}
+
 DocMarkdownWriter::NameAndText DocMarkdownWriter::_getNameAndText(
     ASTMarkup::Entry* entry,
     Decl* decl)
@@ -2973,6 +3002,14 @@ DocumentPage* DocMarkdownWriter::getPage(Decl* decl)
     page->path = path;
     page->shortName = _getName(decl);
     page->decl = decl;
+    if (auto extDecl = as<ExtensionDecl>(decl))
+    {
+        page->shortName = _getName(extDecl);
+        if (auto declRef = isDeclRefTypeOf<Decl>(extDecl->targetType))
+        {
+            page->decl = declRef.getDecl();
+        }
+    }
     m_output[path] = page;
 
     // If parent page exists, add this page to it's children
diff --git a/source/slang/slang-doc-markdown-writer.h b/source/slang/slang-doc-markdown-writer.h
index 36d851e61..f4ca4de7f 100644
--- a/source/slang/slang-doc-markdown-writer.h
+++ b/source/slang/slang-doc-markdown-writer.h
@@ -214,6 +214,7 @@ struct DocMarkdownWriter
     String _getFullName(Decl* decl);
     String _getDocFilePath(Decl* decl);
     String _getName(InheritanceDecl* decl);
+    String _getName(ExtensionDecl* extDecl);
 
     NameAndText _getNameAndText(ASTMarkup::Entry* entry, Decl* decl);
     NameAndText _getNameAndText(Decl* decl);