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The Dart analyzer performs static analysis on Dart code to identify potential issues, enforce coding standards, and improve code quality.
Overview
The analyzer examines Dart code without running it, checking for:
- Syntax errors
- Type errors
- Potential runtime errors
- Coding style violations
- Best practice recommendations
Usage
dart analyze [options] [<directory>]
Basic Examples
Command-Line Options
Fatal Levels
Control which issue levels should cause the analyzer to exit with an error code:
# Treat info-level issues as fatal
dart analyze --fatal-infos
# Treat warnings as fatal (default: true)
dart analyze --fatal-warnings
# Don't treat warnings as fatal
dart analyze --no-fatal-warnings
dart analyze
# Output:
# Analyzing my_app...
#
# error • lib/main.dart:10:5 • Undefined name 'foo' • undefined_name
# warning • lib/utils.dart:25:3 • Unused import • unused_import
#
# 2 issues found.
Advanced Options
# Specify package resolution config
dart analyze --packages=.dart_tool/package_config.json
# Override SDK path
dart analyze --sdk-path=/path/to/dart-sdk
# Set analysis cache location
dart analyze --cache=/tmp/analysis-cache
Configuration
Configure the analyzer using an analysis_options.yaml file at the root of your project:
Basic Configuration
analyzer:
exclude:
- build/**
- '**/*.g.dart'
errors:
# Treat specific issues as errors
unused_import: error
unused_local_variable: warning
language:
strict-casts: true
strict-inference: true
strict-raw-types: true
linter:
rules:
- camel_case_types
- prefer_const_constructors
- avoid_print
Error Severity Levels
You can configure the severity of specific diagnostics:
error - Treat as an error (blocks compilation)warning - Treat as a warninginfo - Treat as an informational messageignore - Suppress the diagnostic
analyzer:
errors:
# Promote warnings to errors
invalid_use_of_protected_member: error
# Demote errors to warnings
unused_element: warning
# Suppress specific diagnostics
todo: ignore
Excluding Files and Directories
Exclude files from analysis:
analyzer:
exclude:
- build/**
- '**/*.g.dart'
- '**/*.freezed.dart'
- test/_data/**
- lib/generated/**
Language Features
Enable strict mode features:
analyzer:
language:
# Require explicit casts
strict-casts: true
# Require type inference to succeed
strict-inference: true
# Disallow raw types (non-generic types)
strict-raw-types: true
Strong Mode
Configure strong mode options (Dart 2.0+):
analyzer:
strong-mode:
implicit-casts: false
implicit-dynamic: false
Linter Rules
The analyzer includes a comprehensive set of lint rules. Enable rules in analysis_options.yaml:
Recommended Rules
Use a curated set of recommended rules:
include: package:lints/recommended.yaml
linter:
rules:
# Additional rules beyond recommended
- prefer_single_quotes
- sort_constructors_first
Core Lints
Use the core lints package:
include: package:lints/core.yaml
Custom Rule Configuration
linter:
rules:
# Style rules
- camel_case_types
- camel_case_extensions
- file_names
- non_constant_identifier_names
# Documentation rules
- package_api_docs
- public_member_api_docs
# Error rules
- avoid_print
- avoid_relative_lib_imports
- prefer_const_constructors
- unnecessary_null_in_if_null_operators
# Performance rules
- prefer_const_constructors_in_immutables
- prefer_const_declarations
- prefer_const_literals_to_create_immutables
Disable Specific Rules
linter:
rules:
# Explicitly disable rules
- avoid_print
# Comment out rules to disable them:
# - public_member_api_docs
Output Examples
Default Output
$ dart analyze
Analyzing my_app...
error • lib/main.dart:15:7 • The name 'unknownFunction' isn't defined. • undefined_name
warning • lib/utils.dart:42:1 • Unused import: 'dart:convert' • unused_import
info • lib/models/user.dart:10:3 • Document all public members • public_member_api_docs
3 issues found.
JSON Output
{
"version": 1,
"diagnostics": [
{
"code": "undefined_name",
"severity": "ERROR",
"type": "COMPILE_TIME_ERROR",
"location": {
"file": "lib/main.dart",
"range": {
"start": {"offset": 245, "line": 15, "column": 7},
"end": {"offset": 260, "line": 15, "column": 22}
}
},
"problemMessage": "The name 'unknownFunction' isn't defined.",
"correctionMessage": "Try correcting the name to one that is defined."
}
]
}
Machine Output
ERROR|COMPILE_TIME_ERROR|UNDEFINED_NAME|lib/main.dart|15|7|15|The name 'unknownFunction' isn't defined.
WARNING|HINT|UNUSED_IMPORT|lib/utils.dart|42|1|13|Unused import: 'dart:convert'
Suppressing Diagnostics
In Code
Suppress specific diagnostics using comments:
// ignore: unused_import
import 'dart:convert';
void main() {
// ignore: avoid_print
print('Hello, world!');
}
// Ignore for the entire file
// ignore_for_file: prefer_const_constructors
class MyWidget {
// ignore: public_member_api_docs
final String name;
}
Multiple Diagnostics
// ignore: unused_import, unnecessary_import
import 'package:some_package/some_package.dart';
File-Level Suppression
// ignore_for_file: avoid_print, public_member_api_docs
void debugLog(String message) {
print(message); // No warning
}
Exit Codes
0 - No issues found1 - Issues found (errors or warnings, depending on configuration)3 - Analysis completed with fatal issues
Integration
CI/CD Integration
#!/bin/bash
set -e
# Run analyzer with strict settings
dart analyze --fatal-infos --fatal-warnings
if [ $? -eq 0 ]; then
echo "Analysis passed!"
else
echo "Analysis failed!"
exit 1
fi
Pre-commit Hook
#!/bin/bash
# Analyze staged Dart files
STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACM | grep "\.dart$")
if [ -n "$STAGED_FILES" ]; then
dart analyze $STAGED_FILES
if [ $? -ne 0 ]; then
echo "Analysis failed. Please fix the issues before committing."
exit 1
fi
fi
Editor Integration
Most editors integrate with the Dart analyzer through the Dart Analysis Server:
- VS Code: Install the Dart extension
- IntelliJ/Android Studio: Built-in Dart plugin
- Vim/Neovim: Use vim-lsc or coc-flutter
- Emacs: Use lsp-mode with lsp-dart
Common Diagnostic Codes
Compile-Time Errors
undefined_name - Reference to undefined identifierundefined_method - Call to undefined methodinvalid_assignment - Type mismatch in assignmentargument_type_not_assignable - Wrong argument type
Warnings
unused_import - Import statement is unusedunused_local_variable - Local variable is never readdead_code - Unreachable code detecteddeprecated_member_use - Use of deprecated API
Hints/Info
unnecessary_cast - Explicit cast is redundantunnecessary_null_comparison - Null check is unnecessaryprefer_const_constructors - Constructor could be const
Cache Location
Set a custom cache directory to improve performance:
dart analyze --cache=/tmp/dart-analysis-cache
Incremental Analysis
The analyzer uses incremental analysis by default, only re-analyzing changed files.
Troubleshooting
Clear Analysis Cache
If you encounter issues, try clearing the analysis cache:
rm -rf .dart_tool/
dart pub get
dart analyze
Verbose Output
Enable verbose output for debugging:
See Also