AvoidContextAcrossAsyncRule class

Warns when BuildContext is used after an await without a mounted check.

Since: v2.3.10 | Updated: v13.0.0 | Rule version: v7

Alias: async_context, stale_context, avoid_using_context_after_dispose

Why This Matters

After an await, the widget may have been unmounted (disposed). If you use context without checking mounted, you risk:

Crashes: Looking up a deactivated widget's ancestor exceptions
Memory leaks: Keeping references to disposed widgets
Undefined behavior: Actions on non-existent UI elements

Detection Patterns

This rule tracks await expressions and mounted guards at the block level:

Resets protection after each await (new async gap = new risk)
Recognizes if (!mounted) return; as protection for subsequent code
Recognizes if (mounted) { ... } as protection for code inside the block
Skips nested callbacks (they have their own valid context scope)

Recognized Mounted Guards

if (!mounted) return;                                // Early exit guard
if (!context.mounted) return;                        // Flutter 3.7+ style
if (mounted == false) return;                        // Explicit comparison
if (mounted) { ... }                                 // Positive block guard
if (context != null && context.mounted) { ... }      // Compound `&&` guard
context.mounted ? context : null                     // Guarded ternary
context != null && context.mounted ? context : null  // Compound ternary

The compound && ternary form is the idiomatic safe pattern for nullable BuildContext? parameters (extension methods, helpers). The rule treats context != null inside such a compound as a guard, not a usage — neither the LHS nor the then-branch context is reported.

BAD:

Future<void> loadData() async {
  final data = await fetchData();
  Navigator.of(context).push(...); // LINT: Context may be invalid!
}

GOOD:

Future<void> loadData() async {
  final data = await fetchData();
  if (!mounted) return;  // Guard against disposed widget
  Navigator.of(context).push(...);
}

ALSO GOOD:

Future<void> loadData() async {
  final data = await fetchData();
  if (mounted) {
    Navigator.of(context).push(...);  // Safe inside mounted block
  }
}

Constructors

AvoidContextAcrossAsyncRule()

Properties

accuracyTarget → AccuracyTarget?: Optional accuracy target for this rule (for documentation and tooling). Does not enforce; used by reports and rule-audit scripts.
no setterinherited
applicableFileTypes → Set<FileType>?: The file types this rule applies to.
no setterinherited
canUseParsedResult → bool: Indicates whether this analysis rule can work with just the parsed information or if it requires a resolved unit.
no setterinherited
certIds → List<String>: CERT coding standard identifiers (e.g. STR02-C). Populate only where there is a clear mapping; leave empty for most rules initially.
no setterinherited
code → LintCode: The lint code for this rule.
no setterinherited
configAliases → List<String>: Alias: require_build_context_scope (deprecated, use avoid_context_across_async)
no setteroverride
conflictingRules → List<String>: Curated opposite/competing rule names.
no setterinherited
cost → RuleCost: The estimated execution cost of this rule.
no setteroverride
cweIds → List<int>: CWE identifiers this rule helps prevent or detect. https://cwe.mitre.org/ — e.g. CWE-798 (Hardcoded Credentials).
no setterinherited
description → String: Short description suitable for display in console output and IDEs.
finalinherited
diagnosticCode → DiagnosticCode: The code to report for a violation.
no setterinherited
diagnosticCodes → List<DiagnosticCode>: The diagnostic codes associated with this analysis rule.
no setterinherited
documentationUrl → String: Returns the documentation URL for this rule.
no setterinherited
effectiveSeverity → DiagnosticSeverity?: Get the effective severity for this rule, considering overrides.
no setterinherited
exampleBad → String?: Short code example that VIOLATES this rule (shown in CLI walkthrough).
no setterinherited
exampleGood → String?: Short code example of COMPLIANT code (shown in CLI walkthrough).
no setterinherited
fixGenerators → List<SaropaFixGenerator>: Fix producer generators for this rule.
no setterinherited
hashCode → int: The hash code for this object.
no setterinherited
hyphenatedName → String: Returns the rule name in hyphenated format for display.
no setterinherited
impact → LintImpact: Context after await can crash when widget is disposed.
no setteroverride
incompatibleRules → List<String>: A list of incompatible rule names.
no setterinherited
isDisabled → bool: Check if this rule is disabled via configuration.
no setterinherited
maximumLineCount → int: Maximum line count for this rule to run.
no setterinherited
minimumLineCount → int: Minimum line count for this rule to run.
no setterinherited
name → String: The rule name.
finalinherited
owasp → OwaspMapping?: OWASP categories this rule helps prevent.
no setterinherited
pubspecVisitor → PubspecVisitor?: A visitor that visits a Pubspec to perform analysis.
no setterinherited
relatedRules → List<String>: Curated "see also" rule names for discoverability in docs/IDE tooling.
no setterinherited
reporter ← DiagnosticReporter: Sets the DiagnosticReporter for the CompilationUnit currently being visited.
no getterinherited
requiredPatterns → Set<String>?: String patterns that must be present in the file for this rule to run.
no setterinherited
requiresAsync → bool: Whether this rule only applies to async code.
no setterinherited
requiresBlocImport → bool: Whether this rule only applies to files that import Bloc.
no setterinherited
requiresClassDeclaration → bool: Whether this rule only applies to files with class declarations.
no setterinherited
requiresFlutterImport → bool: Whether this rule only applies to files that import Flutter.
no setterinherited
requiresImports → bool: Whether this rule only applies to files with imports.
no setterinherited
requiresMainFunction → bool: Whether this rule only applies to files with a main() function.
no setterinherited
requiresProviderImport → bool: Whether this rule only applies to files that import Provider.
no setterinherited
requiresRiverpodImport → bool: Whether this rule only applies to files that import Riverpod.
no setterinherited
requiresWidgets → bool: Whether this rule only applies to Flutter widget code.
no setterinherited
ruleStatus → RuleStatus: Lifecycle status. Default RuleStatus.ready. Use RuleStatus.beta for new or heuristic-heavy rules; RuleStatus.deprecated for sunset.
no setterinherited
ruleType → RuleType?: Semantic type of this rule. Default null = unspecified (legacy). When set, used for quality gates, accuracy targets, and reporting.
no setteroverride
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
skipExampleFiles → bool: Whether to skip example files (example/**).
no setterinherited
skipFixtureFiles → bool: Whether to skip fixture files (fixture/, fixtures/).
no setterinherited
skipGeneratedCode → bool: Whether to skip generated files (*.g.dart, *.freezed.dart, *.gen.dart).
no setterinherited
skipTestFiles → bool: Whether to skip test files (*_test.dart, test/**).
no setterinherited
state → RuleState: The state of this analysis rule.
finalinherited
supersedesRules → List<String>: Rule names this rule supersedes/replaces.
no setterinherited
tags → Set<String>: Tags for filtering and discovery (e.g. in docs, IDE, or CI). Examples: 'performance', 'accessibility', 'suspicious', 'convention'.
no setteroverride
testRelevance → TestRelevance: How this rule relates to test files.
no setterinherited

Methods

noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
registerNodeProcessors(RuleVisitorRegistry registry, RuleContext ruleContext) → void: Registers node processors in the given registry.
inherited
reportAtNode(AstNode? node, {List<Object> arguments = const [], List<DiagnosticMessage>? contextMessages}) → Diagnostic?: Reports a diagnostic at node with message arguments and contextMessages.
inherited
reportAtOffset(int offset, int length, {List<Object> arguments = const [], List<DiagnosticMessage>? contextMessages}) → Diagnostic: Reports a diagnostic at offset, with length, with message arguments and contextMessages.
inherited
reportAtPubNode(PubspecNode node, {List<Object> arguments = const [], List<DiagnosticMessage> contextMessages = const []}) → Diagnostic: Reports a diagnostic at Pubspec node, with message arguments and contextMessages.
inherited
reportAtSourceRange(SourceRange sourceRange, {List<Object> arguments = const [], List<DiagnosticMessage>? contextMessages}) → Diagnostic: Reports a diagnostic at sourceRange, with message arguments and contextMessages.
inherited
reportAtToken(Token token, {List<Object> arguments = const [], List<DiagnosticMessage>? contextMessages}) → Diagnostic?: Reports a diagnostic at token, with message arguments and contextMessages.
inherited
runWithReporter(SaropaDiagnosticReporter reporter, SaropaContext context) → void: Override this method to implement your lint rule.
override
shouldSkipFile(String path) → bool: Check if a file path should be skipped based on context settings.
inherited
toString() → String: A string representation of this object.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited