docs: add a section about default exclusions (#3117)

Author: ldez

Diff for: .golangci.reference.yml

@@ -2097,7 +2097,7 @@ issues:
   # it can be disabled by `exclude-use-default: false`.
   # To list all excluded by default patterns execute `golangci-lint run --help`
   #
-  # Default: []
+  # Default: https://golangci-lint.run/usage/false-positives/#default-exclusions
   exclude:
     - abcdef
 
@@ -2139,9 +2139,24 @@ issues:
   exclude-case-sensitive: false
 
   # The list of ids of default excludes to include or disable.
+  # https://golangci-lint.run/usage/false-positives/#default-exclusions
   # Default: []
   include:
-    - EXC0002 # disable excluding of issues about comments from golint.
+    - EXC0001
+    - EXC0002
+    - EXC0003
+    - EXC0004
+    - EXC0005
+    - EXC0006
+    - EXC0007
+    - EXC0008
+    - EXC0009
+    - EXC0010
+    - EXC0011
+    - EXC0012
+    - EXC0013
+    - EXC0014
+    - EXC0015
 
   # Maximum issues count per one linter.
   # Set to 0 to disable.

Diff for: docs/src/docs/contributing/workflow.mdx

@@ -14,7 +14,7 @@ conduct](https://github.com/golangci/golangci-lint/blob/master/CODE_OF_CONDUCT.m
 Prerequisites:
 
 - `make`
-- [Go 1.13+](https://golang.org/doc/install)
+- [Go](https://golang.org/doc/install)
 
 Fork and clone [golangci-lint](https://github.com/golangci/golangci-lint) repository.
 

Diff for: docs/src/docs/usage/false-positives.mdx

@@ -142,3 +142,10 @@ func someLegacyFunction() *string {
 You can see more examples of using `//nolint` in [our tests](https://github.com/golangci/golangci-lint/tree/master/pkg/result/processors/testdata) for it.
 
 Use `//nolint` instead of `// nolint` because machine-readable comments should have no space by Go convention.
+
+## Default Exclusions
+
+Some exclusions are considered as common, to help golangci-lint users those common exclusions are used as default exclusions.
+
+If you don't want to use it you can set `issues.exclude-use-default` to `false`.
+{.DefaultExclusions}

Diff for: pkg/config/issues.go

@@ -188,15 +188,16 @@ func GetDefaultExcludePatternsStrings() []string {
 	return ret
 }
 
+// TODO(ldez): this behavior must be changed in v2, because this is confusing.
 func GetExcludePatterns(include []string) []ExcludePattern {
-	includeMap := make(map[string]bool, len(include))
+	includeMap := make(map[string]struct{}, len(include))
 	for _, inc := range include {
-		includeMap[inc] = true
+		includeMap[inc] = struct{}{}
 	}
 
 	var ret []ExcludePattern
 	for _, p := range DefaultExcludePatterns {
-		if !includeMap[p.ID] {
+		if _, ok := includeMap[p.ID]; !ok {
 			ret = append(ret, p)
 		}
 	}

Diff for: scripts/expand_website_templates/main.go

@@ -212,13 +212,29 @@ func buildTemplateContext() (map[string]string, error) {
 		"LintersCommandOutputDisabledOnly": string(lintersOutParts[1]),
 		"EnabledByDefaultLinters":          getLintersListMarkdown(true),
 		"DisabledByDefaultLinters":         getLintersListMarkdown(false),
+		"DefaultExclusions":                getDefaultExclusions(),
 		"ThanksList":                       getThanksList(),
 		"RunHelpText":                      string(shortHelp),
 		"ChangeLog":                        string(changeLog),
 		"LatestVersion":                    latestVersion,
 	}, nil
 }
 
+func getDefaultExclusions() string {
+	bufferString := bytes.NewBufferString("")
+
+	for _, pattern := range config.DefaultExcludePatterns {
+		_, _ = fmt.Fprintln(bufferString)
+		_, _ = fmt.Fprintf(bufferString, "### %s\n", pattern.ID)
+		_, _ = fmt.Fprintln(bufferString)
+		_, _ = fmt.Fprintf(bufferString, "- linter: `%s`\n", pattern.Linter)
+		_, _ = fmt.Fprintf(bufferString, "- pattern: `%s`\n", strings.ReplaceAll(pattern.Pattern, "`", "`"))
+		_, _ = fmt.Fprintf(bufferString, "- why: %s\n", pattern.Why)
+	}
+
+	return bufferString.String()
+}
+
 func getLintersListMarkdown(enabled bool) string {
 	var neededLcs []*linter.Config
 	lcs := lintersdb.NewManager(nil, nil).GetAllSupportedLinterConfigs()