Fix missing semantic highlighting in attributes and ExtractExitentialValueExpr. (#2541)

* Fix missing semantic highlighting in attributes and ExtractExitentialValueExpr.

* Fix regression on partially specialized generic expr highlighting.

* Add regression test.

Co-authored-by: Yong He <yhe@nvidia.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/source/slang/slang-workspace-version.cpp b/source/slang/slang-workspace-version.cpp
index d5fc62e79..309d4e51d 100644
--- a/source/slang/slang-workspace-version.cpp
+++ b/source/slang/slang-workspace-version.cpp
@@ -51,7 +51,11 @@ void Workspace::changeDoc(const String& path, LanguageServerProtocol::Range rang
         auto endOffset = doc->getOffset(line, col);
         auto originalText = doc->getText().getUnownedSlice();
         StringBuilder newText;
-        newText << originalText.head(startOffset) << text << originalText.tail(endOffset);
+        if (startOffset != -1)
+            newText << originalText.head(startOffset);
+        newText << text;
+        if (endOffset != -1)
+            newText << originalText.tail(endOffset);
         changeDoc(doc.Ptr(), newText.ProduceString());
     }
 }