Fix if statement block var bug

package.json

@@ -26,7 +26,7 @@
             "ts-node/register"
         ],
         "fullTrace": true,
-        "timeout": 987654321,
+        "timeout": 2000,
         "watchExtensions": [
             "ts"
         ]

src/Program.spec.ts

@@ -509,6 +509,33 @@ describe('Program', () => {
             ]);
         });
 
+        it('supports using vars defined in nested if statements', () => {
+            //call a function that doesn't exist
+            program.setFile({ src: `${rootDir}/source/main.brs`, dest: 'source/main.brs' }, `
+                sub Main()
+                    if true
+                        name = "bob"
+                    end if
+                    print name
+                end sub
+            `);
+
+            program.validate();
+            expectZeroDiagnostics(program);
+        });
+
+        it('supports using `m` vars in parameter default values', () => {
+            //call a function that doesn't exist
+            program.setFile({ src: `${rootDir}/source/main.brs`, dest: 'source/main.brs' }, `
+                sub findNode(nodeId as string, parentNode = m.top as object)
+                    return parentNode.findNode(nodeId)
+                end sub
+            `);
+
+            program.validate();
+            expectZeroDiagnostics(program);
+        });
+
         it('detects methods from another file in a subdirectory', () => {
             program.setFile('source/main.brs', `
                 sub Main()

src/bscPlugin/validation/BrsFileValidator.ts

@@ -1,3 +1,4 @@
+import { interpolatedRange } from '../../astUtils/creators';
 import { isBody, isClassStatement, isCommentStatement, isConstStatement, isDottedGetExpression, isEnumStatement, isForEachStatement, isForStatement, isFunctionStatement, isImportStatement, isInterfaceStatement, isLibraryStatement, isLiteralExpression, isNamespacedVariableNameExpression, isNamespaceStatement, isUnaryExpression, isWhileStatement } from '../../astUtils/reflection';
 import { createVisitor, WalkMode } from '../../astUtils/visitors';
 import { DiagnosticMessages } from '../../DiagnosticMessages';
@@ -8,6 +9,7 @@ import type { AstNode, Expression } from '../../parser/AstNode';
 import type { LiteralExpression } from '../../parser/Expression';
 import { ParseMode } from '../../parser/Parser';
 import type { ContinueStatement, EnumMemberStatement, EnumStatement, ForEachStatement, ForStatement, ImportStatement, LibraryStatement, NamespaceStatement, WhileStatement } from '../../parser/Statement';
+import { SymbolTable } from '../../SymbolTable';
 import { DynamicType } from '../../types/DynamicType';
 import util from '../../util';
 
@@ -95,6 +97,9 @@ export class BrsFileValidator {
             },
             FunctionParameterExpression: (node) => {
                 node.getSymbolTable()?.addSymbol(node.name.text, node.name.range, node.type);
+                //define a symbolTable for each FunctionParameterExpression that contains `m`. TODO, add previous parameter names to this list
+                node.symbolTable = new SymbolTable(node.getSymbolTable());
+                node.symbolTable.addSymbol('m', interpolatedRange, DynamicType.instance);
             },
             ForEachStatement: (node) => {
                 //register the for loop variable

src/parser/Expression.ts

@@ -16,6 +16,7 @@ import { DynamicType } from '../types/DynamicType';
 import type { BscType } from '../types/BscType';
 import { FunctionType } from '../types/FunctionType';
 import { Expression } from './AstNode';
+import { SymbolTable } from '../SymbolTable';
 
 export type ExpressionVisitor = (expression: Expression, parent: Expression) => void;
 
@@ -127,6 +128,11 @@ export class FunctionExpression extends Expression implements TypedefProvider {
         } else {
             this.returnType = DynamicType.instance;
         }
+
+        //if there's a body, and it doesn't have a SymbolTable, assign one
+        if (this.body && !this.body.symbolTable) {
+            this.body.symbolTable = new SymbolTable();
+        }
     }
 
     /**

src/parser/Parser.ts

@@ -94,6 +94,7 @@ import { createVisitor, WalkMode } from '../astUtils/visitors';
 import { createStringLiteral, createToken } from '../astUtils/creators';
 import { Cache } from '../Cache';
 import type { Expression, Statement } from './AstNode';
+import { SymbolTable } from '../SymbolTable';
 
 export class Parser {
     /**
@@ -903,6 +904,8 @@ export class Parser {
             try {
                 //support ending the function with `end sub` OR `end function`
                 func.body = this.block();
+                //attach a new SymbolTable for this function body
+                func.body.symbolTable = new SymbolTable();
             } finally {
                 this.currentFunctionExpression = previousFunctionExpression;
             }

src/parser/Statement.ts

@@ -164,8 +164,6 @@ export class Block extends Statement {
 
     public readonly range: Range;
 
-    public symbolTable = new SymbolTable();
-
     transpile(state: BrsTranspileState) {
         state.blockDepth++;
         let results = [] as TranspileResult;