Fast, configurable, extensible, flexible, and beautiful linter for Go. Drop-in replacement of golint. **`Revive` provides a framework for development of custom rules, and lets you define a strict preset for enhancing your development & code review processes**.
- Provides functionality for disabling a specific rule or the entire linter for a file or a range of lines.
-`golint` allows this only for generated files.
- Optional type checking. Most rules in golint do not require type checking. If you disable them in the config file, revive will run over 6x faster than golint.
- Provides multiple formatters which let us customize the output.
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- [`reviewdog`](https://github.com/reviewdog/reviewdog) - Automated code review tool integrated with any code analysis tools regardless of programming language
- [`Codeac.io`](https://www.codeac.io?ref=revive) - Automated code review service integrates with GitHub, Bitbucket and GitLab (even self-hosted) and helps you fight technical debt.
Since the default behavior of `revive` is compatible with `golint`, without providing any additional flags, the only difference you'd notice is faster execution.
`revive` supports a `-config` flag whose value should correspond to a TOML file describing which rules to use for `revive`'s linting. If not provided, `revive` will try to use a global config file (assumed to be located at `$HOME/revive.toml`). Otherwise, if no configuration TOML file is found then `revive` uses a built-in set of default linting rules.
If you want to use revive with Bazel, take a look at the [rules](https://github.com/atlassian/bazel-tools/tree/master/gorevive) that Atlassian maintains.
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The [Configuration](#configuration) section of this document provides details on how to configure `revive`. Note that while `revive` configuration is in TOML, that of `golangci-lint` is in YAML.
Please notice that if no particular configuration is provided, `revive` will behave as `go-lint` does, i.e. all `go-lint` rules are enabled (the [Available Rules table](#available-rules) details what are the `go-lint` rules). When a configuration is provided, only rules in the configuration are enabled.
-`-exclude [PATTERN]` - pattern for files/directories/packages to be excluded for linting. You can specify the files you want to exclude for linting either as package name (i.e. `github.com/mgechev/revive`), list them as individual files (i.e. `file.go`), directories (i.e. `./foo/...`), or any combination of the three.
-`-formatter [NAME]` - formatter to be used for the output. The currently available formatters are:
Using comments, you can disable the linter for the entire file or only range of lines:
```go
//revive:disable
func Public() {}
//revive:enable
```
The snippet above, will disable `revive` between the `revive:disable` and `revive:enable` comments. If you skip `revive:enable`, the linter will be disabled for the rest of the file.
By default `revive` will enable only the linting rules that are named in the configuration file.
For example, the previous configuration file makes `revive` to enable only _cyclomatic_ and _package-comments_ linting rules.
To enable all available rules you need to add:
```toml
enableAllRules = true
```
This will enable all available rules no matter of what rules are named in the configuration file.
To disable a rule, you simply mark it as disabled in the configuration.
For example:
```toml
[rule.line-length-limit]
Disabled = true
```
When enabling all rules you still need/can provide specific configurations for rules.
The following files is an example configuration were all rules are enabled, with exception to those that are explicitly disabled, and some rules are configured with particular arguments:
The default configuration of `revive` can be found at `defaults.toml`. This will enable all rules available in `golint` and use their default configuration (i.e. the way they are hardcoded in `golint`).
| [`context-as-argument`](./RULES_DESCRIPTIONS.md#context-as-argument) | n/a | `context.Context` should be the first argument of a function. | yes | no |
| [`superfluous-else`](./RULES_DESCRIPTIONS.md#superfluous-else) | n/a | Prevents redundant else statements (extends [`indent-error-flow`](./RULES_DESCRIPTIONS.md#indent-error-flow)) | no | no |
| [`confusing-naming`](./RULES_DESCRIPTIONS.md#confusing-naming) | n/a | Warns on methods with names that differ only by capitalization | no | no |
| [`get-return`](./RULES_DESCRIPTIONS.md#get-return) | n/a | Warns on getters that do not yield any result | no | no |
| [`modifies-parameter`](./RULES_DESCRIPTIONS.md#modifies-parameter) | n/a | Warns on assignments to function parameters | no | no |
| [`confusing-results`](./RULES_DESCRIPTIONS.md#confusing-results) | n/a | Suggests to name potentially confusing function results | no | no |
| [`deep-exit`](./RULES_DESCRIPTIONS.md#deep-exit) | n/a | Looks for program exits in funcs other than `main()` or `init()` | no | no |
| [`unused-parameter`](./RULES_DESCRIPTIONS.md#unused-parameter) | n/a | Suggests to rename or remove unused function parameters | no | no |
| [`unreachable-code`](./RULES_DESCRIPTIONS.md#unreachable-code) | n/a | Warns on unreachable code | no | no |
| [`add-constant`](./RULES_DESCRIPTIONS.md#add-constant) | map | Suggests using constant for magic numbers and string literals | no | no |
| [`flag-parameter`](./RULES_DESCRIPTIONS.md#flag-parameter) | n/a | Warns on boolean parameters that create a control coupling | no | no |
| [`unnecessary-stmt`](./RULES_DESCRIPTIONS.md#unnecessary-stmt) | n/a | Suggests removing or simplifying unnecessary statements | no | no |
| [`struct-tag`](./RULES_DESCRIPTIONS.md#struct-tag) | n/a | Checks common struct tags like `json`,`xml`,`yaml` | no | no |
| [`modifies-value-receiver`](./RULES_DESCRIPTIONS.md#modifies-value-receiver) | n/a | Warns on assignments to value-passed method receivers | no | yes |
| [`constant-logical-expr`](./RULES_DESCRIPTIONS.md#constant-logical-expr) | n/a | Warns on constant logical expressions | no | no |
| [`bool-literal-in-expr`](./RULES_DESCRIPTIONS.md#bool-literal-in-expr)| n/a | Suggests removing Boolean literals from logic expressions | no | no |
| [`redefines-builtin-id`](./RULES_DESCRIPTIONS.md#redefines-builtin-id)| n/a | Warns on redefinitions of builtin identifiers | no | no |
| [`function-result-limit`](./RULES_DESCRIPTIONS.md#function-result-limit) | int | Specifies the maximum number of results a function can return | no | no |
| [`imports-blacklist`](./RULES_DESCRIPTIONS.md#imports-blacklist) | []string | Disallows importing the specified packages | no | no |
| [`range-val-in-closure`](./RULES_DESCRIPTIONS.md#range-val-in-closure)| n/a | Warns if range value is used in a closure dispatched as goroutine| no | no |
| [`waitgroup-by-value`](./RULES_DESCRIPTIONS.md#waitgroup-by-value) | n/a | Warns on functions taking sync.WaitGroup as a by-value parameter | no | no |
| [`atomic`](./RULES_DESCRIPTIONS.md#atomic) | n/a | Check for common mistaken usages of the `sync/atomic` package | no | no |
| [`empty-lines`](./RULES_DESCRIPTIONS.md#empty-lines) | n/a | Warns when there are heading or trailing newlines in a block | no | no |
| [`string-format`](./RULES_DESCRIPTIONS.md#string-format) | map | Warns on specific string literals that fail one or more user-configured regular expressions | no | no |
| [`early-return`](./RULES_DESCRIPTIONS.md#early-return) | n/a | Spots if-then-else statements that can be refactored to simplify code reading | no | no |
| [`unconditional-recursion`](./RULES_DESCRIPTIONS.md#unconditional-recursion) | n/a | Warns on function calls that will lead to (direct) infinite recursion | no | no |
| [`identical-branches`](./RULES_DESCRIPTIONS.md#identical-branches) | n/a | Spots if-then-else statements with identical `then` and `else` branches | no | no |
| [`defer`](./RULES_DESCRIPTIONS.md#defer) | map | Warns on some [defer gotchas](https://blog.learngoprogramming.com/5-gotchas-of-defer-in-go-golang-part-iii-36a1ab3d6ef1) | no | no |
Here you can find how you can configure some of the existing rules:
### `var-naming`
This rule accepts two slices of strings, a whitelist and a blacklist of initialisms. By default the rule behaves exactly as the alternative in `golint` but optionally, you can relax it (see [golint/lint/issues/89](https://github.com/golang/lint/issues/89))
```toml
[rule.var-naming]
arguments = [["ID"], ["VM"]]
```
This way, revive will not warn for identifier called `customId` but will warn that `customVm` should be called `customVM`.
The `sarif` formatter produces outputs in SARIF, for _Static Analysis Results Interchange Format_, a standard JSON-based format for the output of static analysis tools defined and promoted by [OASIS](https://www.oasis-open.org/).
Current supported version of the standard is [SARIF-v2.1.0](https://docs.oasis-open.org/sarif/sarif/v2.1.0/csprd01/sarif-v2.1.0-csprd01.html
**To extend the linter with a custom rule or a formatter you'll have to push it to this repository or fork it**. This is due to the limited `-buildmode=plugin` support which [works only on Linux (with known issues)](https://golang.org/pkg/plugin/).
The `Arguments` type is an alias of the type `[]interface{}`. The arguments of the rule are passed from the configuration file.
#### Example
Let's suppose we have developed a rule called `BanStructNameRule` which disallow us to name a structure with given identifier. We can set the banned identifier by using the TOML configuration file:
- Enable the rule with name `ban-struct-name`. The `Name()` method of our rule should return a string which matches `ban-struct-name`.
- Configure the rule with the argument `Foo`. The list of arguments will be passed to `Apply(*File, Arguments)` together with the target file we're linting currently.
The `Format` method accepts a channel of `Failure` instances and the configuration of the enabled rules. The `Name()` method should return a string different from the names of the already existing rules. This string is used when specifying the formatter when invoking the `revive` CLI tool.
Compared to `golint`, `revive` performs better because it lints the files for each individual rule into a separate goroutine. Here's a basic performance benchmark on MacBook Pro Early 2013 run on kubernetes:
Currently, type checking is enabled by default. If you want to run the linter without type checking, remove all typed rules from the configuration file.
