add 'predeclared' linter (#1606)

Author: nishanths

.golangci.example.yml

@@ -152,10 +152,10 @@ linters-settings:
     # Settings passed to gocritic.
     # The settings key is the name of a supported gocritic checker.
     # The list of supported checkers can be find in https://go-critic.github.io/overview.
-    settings: 
+    settings:
       captLocal: # must be valid enabled check name
         # whether to restrict checker to params only (default true)
-        paramsOnly: true 
+        paramsOnly: true
       elseif:
         # whether to skip balanced if-else pairs (default true)
         skipBalanced: true
@@ -219,13 +219,13 @@ linters-settings:
       #
       # {{ AUTHOR }} {{ COMPANY }} {{ YEAR }}
       # SPDX-License-Identifier: Apache-2.0
-  
+
       # 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.
@@ -321,6 +321,11 @@ linters-settings:
     simple: true
     range-loops: true # Report preallocation suggestions on range loops, true by default
     for-loops: false # Report preallocation suggestions on for loops, false by default
+  predeclared:
+    # comma-separated list of predeclared identifiers to not report on
+    ignore: ""
+    # include method names and field names (i.e., qualified names) in checks
+    q: false
   nolintlint:
     # Enable to ensure that nolint directives are all used. Default is true.
     allow-unused: false

go.mod

@@ -43,6 +43,7 @@ require (
 	github.com/moricho/tparallel v0.2.1
 	github.com/nakabonne/nestif v0.3.0
 	github.com/nishanths/exhaustive v0.1.0
+	github.com/nishanths/predeclared v0.2.1
 	github.com/pkg/errors v0.9.1
 	github.com/polyfloyd/go-errorlint v0.0.0-20201127212506-19bd8db6546f
 	github.com/ryancurrah/gomodguard v1.2.0
@@ -69,7 +70,7 @@ require (
 	github.com/valyala/quicktemplate v1.6.3
 	golang.org/x/sys v0.0.0-20201009025420-dfb3f7c4e634 // indirect
 	golang.org/x/text v0.3.4 // indirect
-	golang.org/x/tools v0.0.0-20201121010211-780cb80bd7fb
+	golang.org/x/tools v0.0.0-20210101214203-2dba1e4ea05c
 	gopkg.in/yaml.v2 v2.4.0
 	honnef.co/go/tools v0.0.1-2020.1.6
 	mvdan.cc/gofumpt v0.0.0-20201129102820-5c11c50e9475

go.sum

@@ -270,6 +270,7 @@ type LintersSettings struct {
 	Makezero    MakezeroSettings
 	Thelper     ThelperSettings
 	Forbidigo   ForbidigoSettings
+	Predeclared PredeclaredSettings
 
 	Custom map[string]CustomLinterSettings
 }
@@ -411,6 +412,11 @@ type ForbidigoSettings struct {
 	Forbid []string `mapstructure:"forbid"`
 }
 
+type PredeclaredSettings struct {
+	Ignore    string `mapstructure:"ignore"`
+	Qualified bool   `mapstructure:"q"`
+}
+
 var defaultLintersSettings = LintersSettings{
 	Lll: LllSettings{
 		LineLength: 120,
@@ -471,6 +477,10 @@ var defaultLintersSettings = LintersSettings{
 	ErrorLint: ErrorLintSettings{
 		Errorf: true,
 	},
+	Predeclared: PredeclaredSettings{
+		Ignore:    "",
+		Qualified: false,
+	},
 }
 
 type CustomLinterSettings struct {

pkg/config/config.go

@@ -0,0 +1,26 @@
+package golinters
+
+import (
+	"github.com/nishanths/predeclared/passes/predeclared"
+	"golang.org/x/tools/go/analysis"
+
+	"github.com/golangci/golangci-lint/pkg/config"
+	"github.com/golangci/golangci-lint/pkg/golinters/goanalysis"
+)
+
+func NewPredeclared(settings *config.PredeclaredSettings) *goanalysis.Linter {
+	a := predeclared.Analyzer
+
+	var cfg map[string]map[string]interface{}
+	if settings != nil {
+		cfg = map[string]map[string]interface{}{
+			a.Name: {
+				predeclared.IgnoreFlag:    settings.Ignore,
+				predeclared.QualifiedFlag: settings.Qualified,
+			},
+		}
+	}
+
+	return goanalysis.NewLinter(a.Name, a.Doc, []*analysis.Analyzer{a}, cfg).
+		WithLoadMode(goanalysis.LoadModeSyntax)
+}

pkg/golinters/predeclared.go

@@ -94,12 +94,14 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 	var exhaustiveCfg *config.ExhaustiveSettings
 	var errorlintCfg *config.ErrorLintSettings
 	var thelperCfg *config.ThelperSettings
+	var predeclaredCfg *config.PredeclaredSettings
 	if m.cfg != nil {
 		govetCfg = &m.cfg.LintersSettings.Govet
 		testpackageCfg = &m.cfg.LintersSettings.Testpackage
 		exhaustiveCfg = &m.cfg.LintersSettings.Exhaustive
 		errorlintCfg = &m.cfg.LintersSettings.ErrorLint
 		thelperCfg = &m.cfg.LintersSettings.Thelper
+		predeclaredCfg = &m.cfg.LintersSettings.Predeclared
 	}
 	const megacheckName = "megacheck"
 	lcs := []*linter.Config{
@@ -342,6 +344,9 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		linter.NewConfig(golinters.NewForbidigo()).
 			WithPresets(linter.PresetStyle).
 			WithURL("https://github.com/ashanbrown/forbidigo"),
+		linter.NewConfig(golinters.NewPredeclared(predeclaredCfg)).
+			WithPresets(linter.PresetStyle).
+			WithURL("https://github.com/nishanths/predeclared"),
 
 		// nolintlint must be last because it looks at the results of all the previous linters for unused nolint directives
 		linter.NewConfig(golinters.NewNoLintLint()).

pkg/lint/lintersdb/manager.go

@@ -0,0 +1,4 @@
+linters-settings:
+  predeclared:
+    ignore: "real,recover"
+    q: true

test/testdata/configs/predeclared.yml

@@ -0,0 +1,27 @@
+//args: -Epredeclared
+package testdata
+
+func hello() {
+	var real int // ERROR "variable real has same name as predeclared identifier"
+	a := A{}
+	copy := Clone(a) // ERROR "variable copy has same name as predeclared identifier"
+
+	// suppress any "declared but not used" errors
+	_ = real
+	_ = a
+	_ = copy
+}
+
+type A struct {
+	true bool
+	foo  int
+}
+
+func Clone(a A) A {
+	return A{
+		true: a.true,
+		foo:  a.foo,
+	}
+}
+
+func recover() {} // ERROR "function recover has same name as predeclared identifier"

test/testdata/predeclared.go

@@ -0,0 +1,28 @@
+//args: -Epredeclared
+//config_path: testdata/configs/predeclared.yml
+package testdata
+
+func hello() {
+	var real int
+	a := A{}
+	copy := Clone(a) // ERROR "variable copy has same name as predeclared identifier"
+
+	// suppress any "declared but not used" errors
+	_ = real
+	_ = a
+	_ = copy
+}
+
+type A struct {
+	true bool // ERROR "field true has same name as predeclared identifier"
+	foo  int
+}
+
+func Clone(a A) A {
+	return A{
+		true: a.true,
+		foo:  a.foo,
+	}
+}
+
+func recover() {}