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| 1 | +/** |
| 2 | + * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | + * |
| 4 | + * This source code is licensed under the MIT license found in the |
| 5 | + * LICENSE file in the root directory of this source tree. |
| 6 | + */ |
| 7 | + |
| 8 | +import traverse from '@babel/traverse'; |
| 9 | +import * as t from '@babel/types'; |
| 10 | +import {CompilerDiagnostic, CompilerError, ErrorCategory} from '..'; |
| 11 | +import {CodegenFunction} from '../ReactiveScopes'; |
| 12 | +import {Result} from '../Utils/Result'; |
| 13 | + |
| 14 | +/** |
| 15 | + * Some common node types that are important for coverage tracking. |
| 16 | + * Based on istanbul-lib-instrument's visitor configuration. |
| 17 | + */ |
| 18 | +const IMPORTANT_INSTRUMENTED_TYPES = new Set([ |
| 19 | + 'ArrowFunctionExpression', |
| 20 | + 'AssignmentPattern', |
| 21 | + // 'BlockStatement', |
| 22 | + // 'ExportDefaultDeclaration', |
| 23 | + // 'ExportNamedDeclaration', |
| 24 | + // 'ClassMethod', |
| 25 | + // 'ClassDeclaration', |
| 26 | + // 'ClassProperty', |
| 27 | + // 'ClassPrivateProperty', |
| 28 | + 'ObjectMethod', |
| 29 | + 'ExpressionStatement', |
| 30 | + 'BreakStatement', |
| 31 | + 'ContinueStatement', |
| 32 | + // 'DebuggerStatement', |
| 33 | + 'ReturnStatement', |
| 34 | + 'ThrowStatement', |
| 35 | + 'TryStatement', |
| 36 | + // 'VariableDeclaration', |
| 37 | + 'VariableDeclarator', |
| 38 | + 'IfStatement', |
| 39 | + 'ForStatement', |
| 40 | + 'ForInStatement', |
| 41 | + 'ForOfStatement', |
| 42 | + 'WhileStatement', |
| 43 | + 'DoWhileStatement', |
| 44 | + 'SwitchStatement', |
| 45 | + 'SwitchCase', |
| 46 | + 'WithStatement', |
| 47 | + 'FunctionDeclaration', |
| 48 | + 'FunctionExpression', |
| 49 | + 'LabeledStatement', |
| 50 | + 'ConditionalExpression', |
| 51 | + 'LogicalExpression', |
| 52 | +]); |
| 53 | + |
| 54 | +/** |
| 55 | + * Check if a node is a manual memoization call that the compiler optimizes away. |
| 56 | + * These include useMemo and useCallback calls, which are intentionally removed |
| 57 | + * by the DropManualMemoization pass. |
| 58 | + */ |
| 59 | +function isManualMemoization(node: t.Node): boolean { |
| 60 | + // Check if this is a useMemo/useCallback call expression |
| 61 | + if (t.isCallExpression(node)) { |
| 62 | + const callee = node.callee; |
| 63 | + if (t.isIdentifier(callee)) { |
| 64 | + return callee.name === 'useMemo' || callee.name === 'useCallback'; |
| 65 | + } |
| 66 | + if (t.isMemberExpression(callee) && t.isIdentifier(callee.property)) { |
| 67 | + return ( |
| 68 | + callee.property.name === 'useMemo' || |
| 69 | + callee.property.name === 'useCallback' |
| 70 | + ); |
| 71 | + } |
| 72 | + } |
| 73 | + |
| 74 | + return false; |
| 75 | +} |
| 76 | + |
| 77 | +/** |
| 78 | + * Create a location key for comparison. We compare by line/column/source, |
| 79 | + * not by object identity. |
| 80 | + */ |
| 81 | +function locationKey(loc: t.SourceLocation): string { |
| 82 | + return `${loc.start.line}:${loc.start.column}-${loc.end.line}:${loc.end.column}`; |
| 83 | +} |
| 84 | + |
| 85 | +/** |
| 86 | + * Validates that important source locations from the original code are preserved |
| 87 | + * in the generated AST. This ensures that Istanbul coverage instrumentation can |
| 88 | + * properly map back to the original source code. |
| 89 | + * |
| 90 | + * The validator: |
| 91 | + * 1. Collects locations from "important" nodes in the original AST (those that |
| 92 | + * Istanbul instruments for coverage tracking) |
| 93 | + * 2. Exempts known compiler optimizations (useMemo/useCallback removal) |
| 94 | + * 3. Verifies that all important locations appear somewhere in the generated AST |
| 95 | + * |
| 96 | + * Missing locations can cause Istanbul to fail to track coverage for certain |
| 97 | + * code paths, leading to inaccurate coverage reports. |
| 98 | + */ |
| 99 | +export function validateSourceLocations( |
| 100 | + originalAst: t.FunctionDeclaration | t.ArrowFunctionExpression | t.FunctionExpression, |
| 101 | + generatedAst: CodegenFunction, |
| 102 | +): Result<void, CompilerError> { |
| 103 | + const errors = new CompilerError(); |
| 104 | + |
| 105 | + // Step 1: Collect important locations from the original source |
| 106 | + const importantOriginalLocations = new Map< |
| 107 | + string, |
| 108 | + {loc: t.SourceLocation; nodeType: string} |
| 109 | + >(); |
| 110 | + |
| 111 | + traverse( |
| 112 | + t.file(t.program([t.isExpression(originalAst) ? t.expressionStatement(originalAst) : originalAst])), |
| 113 | + { |
| 114 | + enter(path) { |
| 115 | + const node = path.node; |
| 116 | + |
| 117 | + // Only track node types that Istanbul instruments |
| 118 | + if (!IMPORTANT_INSTRUMENTED_TYPES.has(node.type)) { |
| 119 | + return; |
| 120 | + } |
| 121 | + |
| 122 | + // Skip manual memoization that the compiler intentionally removes |
| 123 | + if (isManualMemoization(node)) { |
| 124 | + return; |
| 125 | + } |
| 126 | + |
| 127 | + // Collect the location if it exists |
| 128 | + if (node.loc) { |
| 129 | + const key = locationKey(node.loc); |
| 130 | + importantOriginalLocations.set(key, { |
| 131 | + loc: node.loc, |
| 132 | + nodeType: node.type, |
| 133 | + }); |
| 134 | + } |
| 135 | + }, |
| 136 | + }, |
| 137 | + ); |
| 138 | + |
| 139 | + // Step 2: Collect all locations from the generated AST |
| 140 | + const generatedLocations = new Set<string>(); |
| 141 | + |
| 142 | + function collectGeneratedLocations(node: t.Node): void { |
| 143 | + if (node.loc) { |
| 144 | + generatedLocations.add(locationKey(node.loc)); |
| 145 | + } |
| 146 | + |
| 147 | + // Use Babel's VISITOR_KEYS to traverse only actual node properties |
| 148 | + const keys = t.VISITOR_KEYS[node.type as keyof typeof t.VISITOR_KEYS]; |
| 149 | + if (!keys) return; |
| 150 | + |
| 151 | + for (const key of keys) { |
| 152 | + const value = (node as any)[key]; |
| 153 | + |
| 154 | + if (Array.isArray(value)) { |
| 155 | + for (const item of value) { |
| 156 | + if (t.isNode(item)) { |
| 157 | + collectGeneratedLocations(item); |
| 158 | + } |
| 159 | + } |
| 160 | + } else if (t.isNode(value)) { |
| 161 | + collectGeneratedLocations(value); |
| 162 | + } |
| 163 | + } |
| 164 | + } |
| 165 | + |
| 166 | + // Collect from main function body |
| 167 | + collectGeneratedLocations(generatedAst.body); |
| 168 | + |
| 169 | + // Collect from outlined functions |
| 170 | + for (const outlined of generatedAst.outlined) { |
| 171 | + collectGeneratedLocations(outlined.fn.body); |
| 172 | + } |
| 173 | + |
| 174 | + // Step 3: Validate that all important locations are preserved |
| 175 | + for (const [key, {loc, nodeType}] of importantOriginalLocations) { |
| 176 | + if (!generatedLocations.has(key)) { |
| 177 | + errors.pushDiagnostic( |
| 178 | + CompilerDiagnostic.create({ |
| 179 | + category: ErrorCategory.Todo, |
| 180 | + reason: |
| 181 | + 'Important source location missing in generated code', |
| 182 | + description: |
| 183 | + `Source location for ${nodeType} is missing in the generated output. This can cause coverage instrumentation ` + |
| 184 | + `to fail to track this code properly, resulting in inaccurate coverage reports.`, |
| 185 | + }).withDetails({ |
| 186 | + kind: 'error', |
| 187 | + loc, |
| 188 | + message: null, |
| 189 | + }) |
| 190 | + ); |
| 191 | + } |
| 192 | + } |
| 193 | + |
| 194 | + return errors.asResult(); |
| 195 | +} |
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