fix(42238): emit this parameter in function declaration (#46511)

src/compiler/checker.ts

@@ -5657,8 +5657,8 @@ namespace ts {
                 const expandedParams = getExpandedParameters(signature, /*skipUnionExpanding*/ true)[0];
                 // If the expanded parameter list had a variadic in a non-trailing position, don't expand it
                 const parameters = (some(expandedParams, p => p !== expandedParams[expandedParams.length - 1] && !!(getCheckFlags(p) & CheckFlags.RestParameter)) ? signature.parameters : expandedParams).map(parameter => symbolToParameterDeclaration(parameter, context, kind === SyntaxKind.Constructor, options?.privateSymbolVisitor, options?.bundledImports));
-                if (signature.thisParameter) {
-                    const thisParameter = symbolToParameterDeclaration(signature.thisParameter, context);
+                const thisParameter = tryGetThisParameterDeclaration(signature, context);
+                if (thisParameter) {
                     parameters.unshift(thisParameter);
                 }
 
@@ -5713,6 +5713,25 @@ namespace ts {
                 return node;
             }
 
+            function tryGetThisParameterDeclaration(signature: Signature, context: NodeBuilderContext) {
+                if (signature.thisParameter) {
+                    return symbolToParameterDeclaration(signature.thisParameter, context);
+                }
+                if (signature.declaration) {
+                    const thisTag = getJSDocThisTag(signature.declaration);
+                    if (thisTag && thisTag.typeExpression) {
+                        return factory.createParameterDeclaration(
+                            /* decorators */ undefined,
+                            /* modifiers */ undefined,
+                            /* dotDotDotToken */ undefined,
+                            "this",
+                            /* questionToken */ undefined,
+                            typeToTypeNodeHelper(getTypeFromTypeNode(thisTag.typeExpression), context)
+                        );
+                    }
+                }
+            }
+
             function typeParameterToDeclarationWithConstraint(type: TypeParameter, context: NodeBuilderContext, constraintNode: TypeNode | undefined): TypeParameterDeclaration {
                 const savedContextFlags = context.flags;
                 context.flags &= ~NodeBuilderFlags.WriteTypeParametersInQualifiedName; // Avoids potential infinite loop when building for a claimspace with a generic