source map else

compiler/ast.ts

@@ -45,7 +45,7 @@ export type ExprKind =
     | { type: "call"; subject: Expr; args: Expr[] }
     | { type: "unary"; unaryType: UnaryType; subject: Expr }
     | { type: "binary"; binaryType: BinaryType; left: Expr; right: Expr }
-    | { type: "if"; cond: Expr; truthy: Expr; falsy?: Expr }
+    | { type: "if"; cond: Expr; truthy: Expr; falsy?: Expr; elsePos?: Pos }
     | { type: "bool"; value: boolean }
     | { type: "null" }
     | { type: "loop"; body: Expr }

compiler/compiler.ts

@@ -47,7 +47,7 @@ export class Compiler {
 
         const lowerer = new Lowerer(lexer.currentPos());
         lowerer.lower(ast);
-        lowerer.printProgram();
+        // lowerer.printProgram();
         const { program, fnNames } = lowerer.finish();
 
         return { program, fnNames };

compiler/lowerer.ts

@@ -490,7 +490,7 @@ export class Lowerer {
         this.program.setLabel(falseLabel);
 
         if (expr.kind.falsy) {
-            this.addSourceMap(expr.kind.falsy.pos);
+            this.addSourceMap(expr.kind.elsePos!);
             this.lowerExpr(expr.kind.falsy);
         } else {
             this.program.add(Ops.PushNull);

compiler/parser.ts

@@ -456,17 +456,18 @@ export class Parser {
         if (!this.test("else")) {
             return this.expr({ type: "if", cond, truthy }, pos);
         }
+        const elsePos = this.pos();
         this.step();
         if (this.test("if")) {
             const falsy = this.parseIf();
-            return this.expr({ type: "if", cond, truthy, falsy }, pos);
+            return this.expr({ type: "if", cond, truthy, falsy, elsePos }, pos);
         }
         if (!this.test("{")) {
             this.report("expected block");
             return this.expr({ type: "error" }, pos);
         }
         const falsy = this.parseBlock();
-        return this.expr({ type: "if", cond, truthy, falsy }, pos);
+        return this.expr({ type: "if", cond, truthy, falsy, elsePos }, pos);
     }
 
     private parseBinary(): Expr {