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/*
* Copyright 2004 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.javascript.jscomp;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.collect.ImmutableSet;
import com.google.javascript.jscomp.NodeTraversal.ScopedCallback;
import com.google.javascript.jscomp.SyntacticScopeCreator.RedeclarationHandler;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.StaticSourceFile;
import com.google.javascript.rhino.StaticSourceFile.SourceKind;
import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.Set;
import org.jspecify.nullness.Nullable;
/**
* Checks that all variables are declared, that file-private variables are accessed only in the file
* that declares them, and that any var references that cross module boundaries respect declared
* module dependencies.
*/
class VarCheck implements ScopedCallback, CompilerPass {
static final DiagnosticType UNDEFINED_VAR_ERROR = DiagnosticType.error(
"JSC_UNDEFINED_VARIABLE",
"variable {0} is undeclared");
static final DiagnosticType VIOLATED_MODULE_DEP_ERROR =
DiagnosticType.error(
"JSC_VIOLATED_MODULE_DEPENDENCY",
"module {0} cannot reference {2}, defined in module {1}, since {1} loads after {0}");
static final DiagnosticType MISSING_MODULE_DEP_ERROR =
DiagnosticType.warning(
"JSC_MISSING_MODULE_DEPENDENCY",
"missing module dependency; module {0} should depend"
+ " on module {1} because it references {2}");
static final DiagnosticType STRICT_MODULE_DEP_ERROR = DiagnosticType.disabled(
"JSC_STRICT_MODULE_DEPENDENCY",
// The newline below causes the JS compiler not to complain when the
// referenced module's name changes because, for example, it's a
// synthetic module.
"cannot reference {2} because of a missing module dependency\n"
+ "defined in module {1}, referenced from module {0}");
static final DiagnosticType NAME_REFERENCE_IN_EXTERNS_ERROR =
DiagnosticType.warning(
"JSC_NAME_REFERENCE_IN_EXTERNS",
"accessing name {0} in externs has no effect."
+ " Perhaps you forgot to add a var keyword?");
static final DiagnosticType UNDEFINED_EXTERN_VAR_ERROR =
DiagnosticType.warning(
"JSC_UNDEFINED_EXTERN_VAR_ERROR",
"name {0} is not defined in the externs.");
static final DiagnosticType VAR_MULTIPLY_DECLARED_ERROR =
DiagnosticType.error(
"JSC_VAR_MULTIPLY_DECLARED_ERROR",
"Variable {0} declared more than once. First occurrence: {1}");
static final DiagnosticType BLOCK_SCOPED_DECL_MULTIPLY_DECLARED_ERROR =
DiagnosticType.error(
"JSC_BLOCK_SCOPED_DECL_MULTIPLY_DECLARED_ERROR",
"Block-scoped variable {0} declared more than once. First occurrence: {1}");
static final DiagnosticType VAR_ARGUMENTS_SHADOWED_ERROR =
DiagnosticType.error(
"JSC_VAR_ARGUMENTS_SHADOWED_ERROR",
"Shadowing \"arguments\" is not allowed");
// The arguments variable is special, in that it's declared in every local
// scope, but not explicitly declared.
private static final String ARGUMENTS = "arguments";
private static final Node googForwardDeclare = IR.getprop(IR.name("goog"), "forwardDeclare");
// Vars that were referenced in the externs without being declared in externs, even if they were
// defined in code. These will be declared at the end of this pass.
private final Set undefinedNamesFromExterns = new LinkedHashSet<>();
private final AbstractCompiler compiler;
// Whether this is the post-processing validity check.
private final boolean validityCheck;
// Whether extern checks emit error.
private final boolean strictExternCheck;
private RedeclarationCheckHandler dupHandler;
VarCheck(AbstractCompiler compiler) {
this(compiler, false);
}
VarCheck(AbstractCompiler compiler, boolean validityCheck) {
this.compiler = compiler;
this.strictExternCheck = compiler.getErrorLevel(
JSError.make("", 0, 0, UNDEFINED_EXTERN_VAR_ERROR)) == CheckLevel.ERROR;
this.validityCheck = validityCheck;
}
/**
* Creates the scope creator used by this pass. If not in validity check mode, use a {@link
* RedeclarationCheckHandler} to check var redeclarations.
*/
private SyntacticScopeCreator createScopeCreator() {
if (validityCheck) {
return new SyntacticScopeCreator(compiler);
} else {
dupHandler = new RedeclarationCheckHandler();
return new SyntacticScopeCreator(compiler, dupHandler);
}
}
@Override
public void process(Node externs, Node root) {
ScopeCreator scopeCreator = createScopeCreator();
// Don't run externs-checking in sanity check mode. Normalization will
// remove duplicate VAR declarations, which will make
// externs look like they have assigns.
if (!validityCheck) {
NodeTraversal.builder()
.setCompiler(compiler)
.setCallback(new NameRefInExternsCheck())
.setScopeCreator(scopeCreator)
.traverse(externs);
}
NodeTraversal.builder()
.setCompiler(compiler)
.setCallback(this)
.setScopeCreator(scopeCreator)
.traverseRoots(externs, root);
for (String varName : undefinedNamesFromExterns) {
createSynthesizedExternVar(varName, /* isFromUndefinedCodeRef= */ false);
}
if (dupHandler != null) {
dupHandler.removeDuplicates();
}
}
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
return true;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isName()) {
checkName(t, n, parent);
}
}
/** Validates that a NAME node does not refer to an undefined name. */
private void checkName(NodeTraversal t, Node n, Node parent) {
String varName = n.getString();
// Only a function can have an empty name.
if (varName.isEmpty()) {
// Name is optional for function expressions
// x = function() {...}
// Arrow functions are also expressions and cannot have a name
// x = () => {...}
// Member functions have an empty NAME node string, because the actual name is stored on the
// MEMBER_FUNCTION_DEF object that contains the FUNCTION.
// class C { foo() {...} }
// x = { foo() {...} }
checkState(NodeUtil.isFunctionExpression(parent) || NodeUtil.isMethodDeclaration(parent));
return;
}
Scope scope = t.getScope();
Var var = scope.getVar(varName);
// Check that the var has been declared.
if (var == null) {
if ((NodeUtil.isFunctionExpression(parent) || NodeUtil.isClassExpression(parent))
&& n.isFirstChildOf(parent)) {
// e.g. [ function foo() {} ], it's okay if "foo" isn't defined in the
// current scope.
return;
}
if (NodeUtil.isNonlocalModuleExportName(n)) {
// e.g. "export {a as b}" or "import {b as a} from './foo.js'
// where b is defined in a module's export entries but not in any module scope.
return;
}
this.handleUndeclaredVariableRef(t, n);
scope.getGlobalScope().declare(varName, n, compiler.getSynthesizedExternsInput());
return;
}
if (var.isImplicitGoogNamespace()
&& var.getImplicitGoogNamespaceStrength().equals(SourceKind.WEAK)
&& strengthOf(n).equals(SourceKind.STRONG)) {
// This use will be retained but its definition will be deleted.
this.handleUndeclaredVariableRef(t, n);
return;
}
CompilerInput currInput = t.getInput();
CompilerInput varInput = var.getInput();
if (currInput == varInput || currInput == null || varInput == null) {
// The variable was defined in the same file. This is fine.
return;
}
// Check module dependencies.
JSChunk currModule = currInput.getChunk();
JSChunk varModule = varInput.getChunk();
JSChunkGraph moduleGraph = compiler.getModuleGraph();
if (!validityCheck && varModule != currModule && varModule != null && currModule != null) {
if (varModule.isWeak()) {
this.handleUndeclaredVariableRef(t, n);
}
if (moduleGraph.dependsOn(currModule, varModule)) {
// The module dependency was properly declared.
} else {
if (scope.isGlobal()) {
if (moduleGraph.dependsOn(varModule, currModule)) {
// The variable reference violates a declared module dependency.
t.report(
n, VIOLATED_MODULE_DEP_ERROR, currModule.getName(), varModule.getName(), varName);
} else {
// The variable reference is between two modules that have no dependency relationship.
// This should probably be considered an error, but just issue a warning for now.
t.report(
n, MISSING_MODULE_DEP_ERROR, currModule.getName(), varModule.getName(), varName);
}
} else {
t.report(n, STRICT_MODULE_DEP_ERROR, currModule.getName(), varModule.getName(), varName);
}
}
}
}
private static final SourceKind strengthOf(Node n) {
StaticSourceFile source = n.getStaticSourceFile();
if (source == null) {
return SourceKind.EXTERN;
}
return source.getKind();
}
private void handleUndeclaredVariableRef(NodeTraversal t, Node n) {
checkState(n.isName());
String varName = n.getString();
if (n.getParent().isTypeOf()) {
// `typeof` is used for existence checks.
} else if (strictExternCheck && t.getInput().isExtern()) {
// The extern checks are stricter, don't report a second error.
} else {
t.report(n, UNDEFINED_VAR_ERROR, varName);
}
if (validityCheck) {
// When the code is initially traversed, any undeclared variables are treated as
// externs. During this sanity check, we ensure that all variables have either been
// declared or marked as an extern. A failure at this point means that we have created
// some variable/generated some code with an undefined reference.
throw new IllegalStateException("Unexpected variable " + varName);
} else if (!undefinedNamesFromExterns.contains(varName)) {
// Skip this case if the name is already going to be added as an "undefined name from extern"
// That declaration must take priority, to avoid the RemoveUnnecessarySyntheticExterns pass
// accidentally treating the synthetic extern as unnecessary.
createSynthesizedExternVar(varName, /* isFromUndefinedCodeRef= */ true);
}
}
@Override
public void enterScope(NodeTraversal t) {}
@Override
public void exitScope(NodeTraversal t) {
if (!validityCheck && t.inGlobalScope()) {
Scope scope = t.getScope();
// Add symbols that are known to be needed to the standard injected code (polyfills, etc).
for (String requiredSymbol : REQUIRED_SYMBOLS) {
Var var = scope.getVar(requiredSymbol);
if (var == null) {
undefinedNamesFromExterns.add(requiredSymbol);
}
}
}
}
/**
* List of symbols that must always be externed even if they are not referenced anywhere (yet).
* These are used by runtime libraries that might not be present when the first VarCheck runs.
*/
static final ImmutableSet REQUIRED_SYMBOLS =
ImmutableSet.of(
"AggregateError",
"Array",
"Error",
"Float32Array",
"Function",
"Infinity",
"JSCompiler_renameProperty",
"JSCOMPILER_PRESERVE", // added by CheckSideEffects
"Map",
"Math",
"NaN",
"Number",
"Object",
"Promise",
"RangeError",
"Reflect",
"RegExp",
"Set",
"String",
"Symbol",
"TypeError",
"WeakMap",
"global",
"globalThis",
"isNaN",
"parseFloat",
"parseInt",
"self",
"undefined",
"window");
/**
* Create a new variable in a synthetic script. This will prevent subsequent compiler passes from
* crashing.
*/
private void createSynthesizedExternVar(String varName, boolean isFromUndefinedCodeRef) {
Node nameNode = IR.name(varName);
// Mark the variable as constant if it matches the coding convention
// for constant vars.
// NOTE(nicksantos): honestly, I'm not sure how much this matters.
// AFAIK, all people who use the CONST coding convention also
// compile with undeclaredVars as errors. We have some test
// cases for this configuration though, and it makes them happier.
if (compiler.getCodingConvention().isConstant(varName)) {
nameNode.putBooleanProp(Node.IS_CONSTANT_NAME, true);
}
Node syntheticExternVar = IR.var(nameNode);
syntheticExternVar.setIsSynthesizedUnfulfilledNameDeclaration(isFromUndefinedCodeRef);
getSynthesizedExternsRoot(compiler).addChildToBack(syntheticExternVar);
compiler.reportChangeToEnclosingScope(syntheticExternVar);
}
/**
* A check for name references in the externs inputs. These used to prevent a variable from
* getting renamed, but no longer have any effect.
*/
private class NameRefInExternsCheck implements NodeTraversal.Callback {
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
// Type summaries are generated from code rather than hand-written,
// so warning about name references there would usually not be helpful.
return !n.isScript() || !NodeUtil.isFromTypeSummary(n);
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isName()) {
switch (parent.getToken()) {
case VAR:
case LET:
case CONST:
case FUNCTION:
case CLASS:
case PARAM_LIST:
case DEFAULT_VALUE:
case ITER_REST:
case OBJECT_REST:
case ARRAY_PATTERN:
// These are okay.
return;
case STRING_KEY:
if (parent.getParent().isObjectPattern()) {
return;
}
break;
case GETPROP:
if (n == parent.getFirstChild()) {
Scope scope = t.getScope();
Var var = scope.getVar(n.getString());
if (var != null) {
return;
}
if (parent.matchesQualifiedName(googForwardDeclare)) {
// Allow using `goog.forwardDeclare` in the externs without an externs definition
// of goog.
return;
}
t.report(n, UNDEFINED_EXTERN_VAR_ERROR, n.getString());
undefinedNamesFromExterns.add(n.getString());
}
return;
case ASSIGN:
// Don't warn for the "window.foo = foo;" nodes added by
// DeclaredGlobalExternsOnWindow, nor for alias declarations
// of the form "/** @const */ ns.Foo = Bar;"
if (n == parent.getLastChild()
&& n.isQualifiedName()
&& parent.getFirstChild().isQualifiedName()) {
return;
}
break;
case NAME:
// Don't warn for simple var assignments "/** @const */ var foo = bar;"
// They are used to infer the types of namespace aliases.
if (NodeUtil.isNameDeclaration(parent.getParent())) {
return;
}
break;
case OR:
// Don't warn for namespace declarations: "/** @const */ var ns = ns || {};"
if (NodeUtil.isNamespaceDecl(parent.getParent())) {
return;
}
break;
default:
break;
}
t.report(n, NAME_REFERENCE_IN_EXTERNS_ERROR, n.getString());
Scope scope = t.getScope();
Var var = scope.getVar(n.getString());
if (var == null) {
undefinedNamesFromExterns.add(n.getString());
}
}
}
}
/** Returns true if duplication warnings are suppressed on either n or origVar. */
static boolean hasDuplicateDeclarationSuppression(
AbstractCompiler compiler, Node n, Node origVar) {
// For VarCheck and VariableReferenceCheck, variables in externs do not generate duplicate
// warnings.
if (isExternNamespace(n)) {
return true;
}
return TypeValidator.hasDuplicateDeclarationSuppression(compiler, origVar);
}
/** Returns true if n is the name of a variable that declares a namespace in an externs file. */
static boolean isExternNamespace(Node n) {
return n.getParent().isVar() && n.isFromExterns() && NodeUtil.isNamespaceDecl(n);
}
/**
* The handler for duplicate declarations.
*/
private class RedeclarationCheckHandler implements RedeclarationHandler {
private final ArrayList dupDeclNodes = new ArrayList<>();
@Override
public void onRedeclaration(
Scope s, String name, Node n, CompilerInput input) {
Node parent = NodeUtil.getDeclaringParent(n);
Var origVar = s.getVar(name);
// origNode will be null for `arguments`, since there's no node that declares it.
Node origNode = origVar.getNode();
Node origParent = (origNode == null) ? null : NodeUtil.getDeclaringParent(origNode);
switch (parent.getToken()) {
case CLASS:
case CONST:
case LET:
reportBlockScopedMultipleDeclaration(n, name, origNode);
return;
default:
break;
}
if (origParent != null) {
switch (origParent.getToken()) {
case CLASS:
case CONST:
case LET:
reportBlockScopedMultipleDeclaration(n, name, origNode);
return;
case FUNCTION:
// Redeclarations of functions in global scope are fairly common, so allow them
// (at least for now).
if (!s.isGlobal() && parent.isFunction()) {
reportBlockScopedMultipleDeclaration(n, name, origNode);
return;
}
break;
default:
break;
}
}
// Don't allow multiple variables to be declared at the top-level scope
if (s.isGlobal()) {
if (origParent.isCatch() && parent.isCatch()) {
// Okay, both are 'catch(x)' variables.
return;
}
boolean allowDupe = hasDuplicateDeclarationSuppression(compiler, n, origVar.getNameNode());
if (VarCheck.isExternNamespace(n)) {
this.dupDeclNodes.add(parent);
return;
}
if (!allowDupe) {
reportVarMultiplyDeclared(compiler, n, name, origNode);
}
} else if (name.equals(ARGUMENTS)
&& !(NodeUtil.isNameDeclaration(n.getParent()) && n.isName())) {
// Disallow shadowing "arguments" as we can't handle with our current
// scope modeling.
compiler.report(JSError.make(n, VAR_ARGUMENTS_SHADOWED_ERROR));
}
}
public void removeDuplicates() {
for (Node n : dupDeclNodes) {
Node parent = n.getParent();
if (parent != null) {
n.detach();
compiler.reportChangeToEnclosingScope(parent);
}
}
}
}
static void reportVarMultiplyDeclared(
AbstractCompiler compiler, Node current, String name, @Nullable Node original) {
compiler.report(JSError.make(current, VAR_MULTIPLY_DECLARED_ERROR, name, locationOf(original)));
}
private void reportBlockScopedMultipleDeclaration(
Node current, String name, @Nullable Node original) {
compiler.report(
JSError.make(
current, BLOCK_SCOPED_DECL_MULTIPLY_DECLARED_ERROR, name, locationOf(original)));
}
private static String locationOf(@Nullable Node n) {
return (n == null) ? "" : n.getLocation();
}
/** Lazily create a "new" externs root for undeclared variables. */
private static Node getSynthesizedExternsRoot(AbstractCompiler compiler) {
return compiler.getSynthesizedExternsInput().getAstRoot(compiler);
}
}
