Handle typed if/case/while-let in VariableTypeCollector

Author: fwcd

lib/IDE/IDETypeChecking.cpp

@@ -808,6 +808,20 @@ class VariableTypeCollector : public SourceEntityWalker {
       auto TyOffset = getTypeOffset(Buffer.str());
       bool HasExplicitType =
           VD->getTypeReprOrParentPatternTypeRepr() != nullptr;
+      // Handle typed if/guard/while-let as a special case (e.g. `if let x: Int
+      // = Optional.some(4)`), since the `TypedPattern` is not the top-level
+      // pattern here - instead it is an implicit `OptionalSomePattern`
+      if (!HasExplicitType) {
+        if (auto *somePattern =
+                dyn_cast_or_null<OptionalSomePattern>(VD->getParentPattern())) {
+          if (somePattern->isImplicit()) {
+            if (auto *typedPattern =
+                    dyn_cast<TypedPattern>(somePattern->getSubPattern())) {
+              HasExplicitType = typedPattern->getTypeRepr() != nullptr;
+            }
+          }
+        }
+      }
       // Add the type information to the result list.
       Results.emplace_back(VarOffset, VarLength, HasExplicitType, TyOffset);
     }