Rename OptionalCall -> Optional for clarity

The previous OptionalCall terminal and reactive value kinds are now used not 
just for optional calls, but for optional member expressions that appear within 
an optional call. This PR renames those data types to OptionalTerminal and 
OptionalExpression for clarity.

compiler/forget/src/HIR/BuildHIR.ts

@@ -1815,7 +1815,7 @@ function lowerOptionalMemberExpression(
 
   builder.terminateWithContinuation(
     {
-      kind: "optional-call",
+      kind: "optional",
       optional,
       test: testBlock,
       fallthrough: continuationBlock.id,
@@ -1966,7 +1966,7 @@ function lowerOptionalCallExpression(
 
   builder.terminateWithContinuation(
     {
-      kind: "optional-call",
+      kind: "optional",
       optional,
       test: testBlock,
       fallthrough: continuationBlock.id,

compiler/forget/src/HIR/HIR.ts

@@ -118,9 +118,9 @@ export type ReactiveSequenceValue = {
 };
 
 export type ReactiveOptionalCallValue = {
-  kind: "OptionalCall";
+  kind: "OptionalExpression";
   id: InstructionId;
-  call: ReactiveValue;
+  value: ReactiveValue;
   optional: boolean;
   loc: SourceLocation;
 };
@@ -275,7 +275,7 @@ export type Terminal =
   | WhileTerminal
   | LogicalTerminal
   | TernaryTerminal
-  | OptionalCallTerminal
+  | OptionalTerminal
   | LabelTerminal;
 
 function _staticInvariantTerminalHasLocation(
@@ -421,11 +421,12 @@ export type LabelTerminal = {
   loc: SourceLocation;
 };
 
-export type OptionalCallTerminal = {
-  kind: "optional-call";
-  // Whether the call itself is optional. If false, this means that the callee itself
-  // is optionally evaluated (has some OptionalMemberExpresion) but the final call is
-  // required (if the callee is not null/undefined).
+export type OptionalTerminal = {
+  kind: "optional";
+  // Specifies whether this node was optional. If false, it means that the original
+  // node was part of an optional chain but this specific item was non-optional.
+  // For example, in `a?.b.c?.()`, the `.b` access is non-optional but appears within
+  // an optional chain.
   optional: boolean;
   test: BlockId;
   fallthrough: BlockId;

compiler/forget/src/HIR/HIRBuilder.ts

@@ -652,7 +652,7 @@ export function reversePostorderBlocks(func: HIR): void {
         }
         break;
       }
-      case "optional-call":
+      case "optional":
       case "ternary":
       case "logical": {
         visit(terminal.test);

compiler/forget/src/HIR/PrintHIR.ts

@@ -80,7 +80,7 @@ export function printMixedHIR(
   }
   switch (value.kind) {
     case "label":
-    case "optional-call":
+    case "optional":
     case "branch":
     case "if":
     case "logical":
@@ -158,8 +158,8 @@ export function printTerminal(terminal: Terminal): Array<string> | string {
       value = `[${terminal.id}] Ternary test:bb${terminal.test} fallthrough=bb${terminal.fallthrough}`;
       break;
     }
-    case "optional-call": {
-      value = `[${terminal.id}] OptionalCall test:bb${terminal.test} fallthrough=bb${terminal.fallthrough}`;
+    case "optional": {
+      value = `[${terminal.id}] Optional test:bb${terminal.test} fallthrough=bb${terminal.fallthrough}`;
       break;
     }
     case "throw": {
@@ -458,8 +458,8 @@ export function printInstructionValue(instrValue: ReactiveValue): string {
       value = `Global ${instrValue.name}`;
       break;
     }
-    case "OptionalCall": {
-      value = `OptionalCall ${printInstructionValue(instrValue.call)}`;
+    case "OptionalExpression": {
+      value = `OptionalExpression ${printInstructionValue(instrValue.value)}`;
       break;
     }
     case "RegExpLiteral": {

compiler/forget/src/HIR/visitors.ts

@@ -598,11 +598,11 @@ export function mapTerminalSuccessors(
         loc: terminal.loc,
       };
     }
-    case "optional-call": {
+    case "optional": {
       const test = fn(terminal.test);
       const fallthrough = fn(terminal.fallthrough);
       return {
-        kind: "optional-call",
+        kind: "optional",
         optional: terminal.optional,
         test,
         fallthrough,
@@ -721,7 +721,7 @@ export function terminalFallthrough(terminal: Terminal): BlockId | null {
     case "if":
     case "label":
     case "logical":
-    case "optional-call":
+    case "optional":
     case "switch":
     case "ternary":
     case "while": {
@@ -768,7 +768,7 @@ export function mapOptionalFallthroughs(
       const _: BlockId = terminal.fallthrough;
       break;
     }
-    case "optional-call": {
+    case "optional": {
       const _: BlockId = terminal.fallthrough;
       break;
     }
@@ -834,7 +834,7 @@ export function* eachTerminalSuccessor(terminal: Terminal): Iterable<BlockId> {
       }
       break;
     }
-    case "optional-call":
+    case "optional":
     case "ternary":
     case "logical": {
       yield terminal.test;
@@ -906,7 +906,7 @@ export function mapTerminalOperands(
       break;
     }
     case "label":
-    case "optional-call":
+    case "optional":
     case "ternary":
     case "logical":
     case "do-while":
@@ -953,7 +953,7 @@ export function* eachTerminalOperand(terminal: Terminal): Iterable<Place> {
       break;
     }
     case "label":
-    case "optional-call":
+    case "optional":
     case "ternary":
     case "logical":
     case "do-while":

compiler/forget/src/Inference/InlineUseMemo.ts

@@ -171,7 +171,7 @@ export function inlineUseMemo(fn: HIRFunction): void {
               }
               // These all have non-nullable fallthroughs: there is always some code in the
               // CFG that succeeds them which we should find instead
-              case "optional-call":
+              case "optional":
               case "ternary":
               case "logical":
               case "while":
@@ -282,7 +282,7 @@ function getTerminalBlock(cfg: HIR, start: BlockId): BasicBlock {
           return current;
         }
       }
-      case "optional-call":
+      case "optional":
       case "ternary":
       case "logical":
       case "while":

compiler/forget/src/ReactiveScopes/BuildReactiveFunction.ts

@@ -560,7 +560,7 @@ class Driver {
 
         break;
       }
-      case "optional-call":
+      case "optional":
       case "ternary":
       case "logical": {
         const fallthroughId = terminal.fallthrough;
@@ -756,7 +756,7 @@ class Driver {
     id: InstructionId;
   } {
     switch (terminal.kind) {
-      case "optional-call": {
+      case "optional": {
         const test = this.visitValueBlock(terminal.test, terminal.loc);
         const testBlock = this.cx.ir.blocks.get(test.block)!;
         invariant(
@@ -785,9 +785,9 @@ class Driver {
         return {
           place: { ...consequent.place },
           value: {
-            kind: "OptionalCall",
+            kind: "OptionalExpression",
             optional: terminal.optional,
-            call: call,
+            value: call,
             id: terminal.id,
             loc: terminal.loc,
           },

compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts

@@ -684,8 +684,8 @@ function codegenInstructionValue(
       value = createCallExpression(instrValue.loc, callee, args);
       break;
     }
-    case "OptionalCall": {
-      const optionalValue = codegenInstructionValue(cx, instrValue.call);
+    case "OptionalExpression": {
+      const optionalValue = codegenInstructionValue(cx, instrValue.value);
       switch (optionalValue.type) {
         case "OptionalCallExpression":
         case "CallExpression": {

compiler/forget/src/ReactiveScopes/MergeOverlappingReactiveScopes.ts

@@ -125,7 +125,7 @@ class Visitor extends ReactiveFunctionVisitor<Context> {
     if (
       instruction.value.kind === "ConditionalExpression" ||
       instruction.value.kind === "LogicalExpression" ||
-      instruction.value.kind === "OptionalCall"
+      instruction.value.kind === "OptionalExpression"
     ) {
       state.enter(() => {
         super.visitInstruction(instruction, state);

compiler/forget/src/ReactiveScopes/PrintReactiveFunction.ts

@@ -151,11 +151,11 @@ function printReactiveValue(writer: Writer, value: ReactiveValue): void {
       });
       break;
     }
-    case "OptionalCall": {
-      writer.append(`OptionalCall optional=${value.optional}`);
+    case "OptionalExpression": {
+      writer.append(`OptionalExpression optional=${value.optional}`);
       writer.newline();
       writer.indented(() => {
-        printReactiveValue(writer, value.call);
+        printReactiveValue(writer, value.value);
       });
       break;
     }

compiler/forget/src/ReactiveScopes/PropagateScopeDependencies.ts

@@ -450,9 +450,9 @@ class PropagationVisitor extends ReactiveFunctionVisitor<Context> {
     value: ReactiveValue
   ): void {
     switch (value.kind) {
-      case "OptionalCall": {
+      case "OptionalExpression": {
         context.enterConditional(() => {
-          this.visitReactiveValue(context, id, value.call);
+          this.visitReactiveValue(context, id, value.value);
         });
         break;
       }

compiler/forget/src/ReactiveScopes/PruneNonEscapingScopes.ts

@@ -525,7 +525,7 @@ function computeMemoizationInputs(
         rvalues: [value.value],
       };
     }
-    case "OptionalCall":
+    case "OptionalExpression":
     case "RegExpLiteral":
     case "FunctionExpression":
     case "TaggedTemplateExpression":

compiler/forget/src/ReactiveScopes/visitors.ts

@@ -41,8 +41,8 @@ export class ReactiveFunctionVisitor<TState = void> {
   }
   traverseValue(id: InstructionId, value: ReactiveValue, state: TState): void {
     switch (value.kind) {
-      case "OptionalCall": {
-        this.visitValue(id, value.call, state);
+      case "OptionalExpression": {
+        this.visitValue(id, value.value, state);
         break;
       }
       case "LogicalExpression": {
@@ -290,8 +290,8 @@ export function* eachReactiveValueOperand(
   instrValue: ReactiveValue
 ): Iterable<Place> {
   switch (instrValue.kind) {
-    case "OptionalCall": {
-      yield* eachReactiveValueOperand(instrValue.call);
+    case "OptionalExpression": {
+      yield* eachReactiveValueOperand(instrValue.value);
       break;
     }
     case "LogicalExpression": {

compiler/forget/src/Utils/VisualizeHIRMermaid.ts

@@ -114,8 +114,8 @@ function printTerminalLabel(terminal: Terminal): string {
       buffer.push("Ternary");
       break;
     }
-    case "optional-call": {
-      buffer.push("OptionalCall");
+    case "optional": {
+      buffer.push("Optional");
       break;
     }
     case "do-while": {
@@ -175,7 +175,7 @@ function printTerminalArrows(blockId: BlockId, terminal: Terminal): string {
       buffer.push(printJumpArrow(blockId, terminal.fallthrough, "fallthrough"));
       break;
     }
-    case "optional-call": {
+    case "optional": {
       buffer.push(printJumpArrow(blockId, terminal.test, "test"));
       buffer.push(printJumpArrow(blockId, terminal.fallthrough, "fallthrough"));
       break;