exhaustive: add new flags/settings and related tests

New flags:
  ignore-enum-members
  checking-strategy

Deprecated flags:
  ignore-pattern

Author: nishanths

.golangci.example.yml

@@ -136,10 +136,16 @@ linters-settings:
   exhaustive:
     # check switch statements in generated files also
     check-generated: false
-    # indicates that switch statements are to be considered exhaustive if a
-    # 'default' case is present, even if all enum members aren't listed in the
-    # switch
+    # presence of "default" case in switch statements satisfies exhaustiveness,
+    # even if all enum members are not listed
     default-signifies-exhaustive: false
+    # enum members matching the supplied regex do not have to be listed in
+    # switch statements to satisfy exhaustiveness
+    ignore-enum-members: ""
+    # strategy to use when checking exhaustiveness of switch statements; one of:
+    # "name", "value"; see documentation for details:
+    # https://pkg.go.dev/github.com/nishanths/exhaustive#section-documentation
+    checking-strategy: "value"
 
   exhaustivestruct:
     # Struct Patterns is list of expressions to match struct packages and names

pkg/config/linters_settings.go

@@ -57,6 +57,8 @@ var defaultLintersSettings = LintersSettings{
 	Exhaustive: ExhaustiveSettings{
 		CheckGenerated:             false,
 		DefaultSignifiesExhaustive: false,
+		IgnoreEnumMembers:          "",
+		CheckingStrategy:           "value",
 	},
 	Gofumpt: GofumptSettings{
 		LangVersion: "",
@@ -184,7 +186,9 @@ type ErrorLintSettings struct {
 type ExhaustiveSettings struct {
 	CheckGenerated             bool   `mapstructure:"check-generated"`
 	DefaultSignifiesExhaustive bool   `mapstructure:"default-signifies-exhaustive"`
-	IgnorePattern              string `mapstructure:"ignore-pattern"`
+	IgnorePattern              string `mapstructure:"ignore-pattern"` // Deprecated: this setting has no effect; see IgnoreEnumMembers instead.
+	IgnoreEnumMembers          string `mapstructure:"ignore-enum-members"`
+	CheckingStrategy           string `mapstructure:"checking-strategy"`
 }
 
 type ExhaustiveStructSettings struct {

pkg/golinters/exhaustive.go

@@ -18,6 +18,8 @@ func NewExhaustive(settings *config.ExhaustiveSettings) *goanalysis.Linter {
 				exhaustive.CheckGeneratedFlag:             settings.CheckGenerated,
 				exhaustive.DefaultSignifiesExhaustiveFlag: settings.DefaultSignifiesExhaustive,
 				exhaustive.IgnorePatternFlag:              settings.IgnorePattern,
+				exhaustive.IgnoreEnumMembersFlag:          settings.IgnoreEnumMembers,
+				exhaustive.CheckingStrategyFlag:           settings.CheckingStrategy,
 			},
 		}
 	}

test/testdata/configs/exhaustive_ignore_enum_members.yml

@@ -0,0 +1,3 @@
+linters-settings:
+  exhaustive:
+    ignore-enum-members: "East$"

test/testdata/exhaustive_default.go

@@ -11,6 +11,10 @@ const (
 	West
 )
 
+// Should not report missing cases in the switch statement below even though
+// some enum members (East, West) are not listed, because the switch statement
+// has a 'default' case and the default-signifies-exhaustive setting is true.
+
 func processDirectionDefault(d Direction) {
 	switch d {
 	case North, South:

test/testdata/exhaustive_ignore_enum_members.go

@@ -0,0 +1,21 @@
+//args: -Eexhaustive
+//config_path: testdata/configs/exhaustive_ignore_enum_members.yml
+package testdata
+
+type Direction int
+
+const (
+	North Direction = iota
+	East
+	South
+	West
+)
+
+// Should only report East as missing because the enum member West is ignored
+// using the ignore-enum-members setting.
+
+func processDirectionIgnoreEnumMembers(d Direction) {
+	switch d { // ERROR "missing cases in switch of type Direction: East"
+	case North, South:
+	}
+}