feat: Handle omitzero in structfield linter

tools/structfield/structfield.go

@@ -146,18 +146,96 @@ func processTag(structName string, goField *ast.Ident, field *ast.Field, structT
 		return
 	}
 
-	if strings.Contains(tagName, ",omitempty") {
-		checkGoFieldType(structName, goField.Name, field, field.Type.Pos(), pass, allowedTagTypes)
+	hasOmitEmpty := strings.Contains(tagName, ",omitempty")
+	hasOmitZero := strings.Contains(tagName, ",omitzero")
+
+	if hasOmitEmpty || hasOmitZero {
+		if tagType == "url" && hasOmitZero {
+			const msg = "the %q field in struct %q uses unsupported omitzero tag for URL tags"
+			pass.Reportf(field.Pos(), msg, goField.Name, structName)
+		} else {
+			checkGoFieldType(structName, goField.Name, field, field.Pos(), pass, allowedTagTypes, hasOmitEmpty, hasOmitZero)
+		}
+		tagName = strings.ReplaceAll(tagName, ",omitzero", "")
 		tagName = strings.ReplaceAll(tagName, ",omitempty", "")
 	}
-
-	if tagType == "url" {
+	if tagType == "url" && hasOmitEmpty {
 		tagName = strings.ReplaceAll(tagName, ",comma", "")
 	}
-
 	checkGoFieldName(structName, goField.Name, tagName, goField.Pos(), pass, allowedTagNames)
 }
 
+func checkAndReportInvalidTypesForOmitzero(structName, goFieldName string, fieldType ast.Expr, tokenPos token.Pos, pass *analysis.Pass) bool {
+	switch ft := fieldType.(type) {
+	case *ast.StarExpr:
+		if ident, ok := ft.X.(*ast.Ident); ok {
+			// Check for *Struct
+			if obj := pass.TypesInfo.ObjectOf(ident); obj != nil {
+				if _, ok := obj.Type().Underlying().(*types.Struct); ok {
+					return true
+				}
+			}
+			// Check for *builtin
+			if isBuiltinType(ident.Name) {
+				const msg = `the %q field in struct %q uses "omitzero" with a primitive type; remove "omitzero" and use only "omitempty" for pointer primitive types"`
+				pass.Reportf(tokenPos, msg, goFieldName, structName)
+				return true
+			}
+		}
+
+		if arrType, ok := ft.X.(*ast.ArrayType); ok {
+			// For *[]Struct
+			if ident, ok := arrType.Elt.(*ast.Ident); ok {
+				if obj := pass.TypesInfo.ObjectOf(ident); obj != nil {
+					if _, ok := obj.Type().Underlying().(*types.Struct); ok {
+						const msg = "change the %q field type to %q in the struct %q"
+						pass.Reportf(tokenPos, msg, goFieldName, "[]*"+ident.Name, structName)
+						return true
+					}
+				}
+			}
+			// For *[]*Struct
+			if starExpr, ok := arrType.Elt.(*ast.StarExpr); ok {
+				if ident, ok := starExpr.X.(*ast.Ident); ok {
+					const msg = "change the %q field type to %q in the struct %q"
+					pass.Reportf(tokenPos, msg, goFieldName, "[]*"+ident.Name, structName)
+					return true
+				}
+			}
+			// For *[]builtin
+			if ident, ok := arrType.Elt.(*ast.Ident); ok && isBuiltinType(ident.Name) {
+				const msg = "change the %q field type to %q in the struct %q"
+				pass.Reportf(tokenPos, msg, goFieldName, "[]"+ident.Name, structName)
+				return true
+			}
+		}
+		if _, ok := ft.X.(*ast.MapType); ok {
+			return true
+		}
+	// Slice
+	case *ast.ArrayType:
+		return true
+
+	// Map
+	case *ast.MapType:
+		return true
+
+	// Struct
+	case *ast.Ident:
+		if obj := pass.TypesInfo.ObjectOf(ft); obj != nil {
+			switch obj.Type().Underlying().(type) {
+			case *types.Struct:
+				return true
+			case *types.Basic:
+				const msg = `the %q field in struct %q uses "omitzero" with a primitive type; remove "omitzero", as it is only allowed with structs, maps, and slices`
+				pass.Reportf(tokenPos, msg, goFieldName, structName)
+				return true
+			}
+		}
+	}
+	return false
+}
+
 func checkGoFieldName(structName, goFieldName, tagName string, tokenPos token.Pos, pass *analysis.Pass, allowedNames map[string]bool) {
 	fullName := structName + "." + goFieldName
 	if allowedNames[fullName] {
@@ -171,16 +249,36 @@ func checkGoFieldName(structName, goFieldName, tagName string, tokenPos token.Po
 	}
 }
 
-func checkGoFieldType(structName, goFieldName string, field *ast.Field, tokenPos token.Pos, pass *analysis.Pass, allowedTypes map[string]bool) {
+func checkGoFieldType(structName, goFieldName string, field *ast.Field, tokenPos token.Pos, pass *analysis.Pass, allowedTypes map[string]bool, omitempty, omitzero bool) {
 	if allowedTypes[structName+"."+goFieldName] {
 		return
 	}
+	switch {
+	case omitempty && omitzero:
+		skipOmitzero := checkAndReportInvalidTypesForOmitzero(structName, goFieldName, field.Type, tokenPos, pass)
+		skipOmitempty := checkAndReportInvalidTypes(structName, goFieldName, field.Type, tokenPos, pass)
+		if !skipOmitzero {
+			const msg = `the %q field in struct %q uses "omitzero"; remove "omitzero", as it is only allowed with structs, maps, and slices`
+			pass.Reportf(tokenPos, msg, goFieldName, structName)
+		}
+		if !skipOmitempty {
+			const msg = `change the %q field type to %q in the struct %q because its tag uses "omitempty"`
+			pass.Reportf(tokenPos, msg, goFieldName, "*"+exprToString(field.Type), structName)
+		}
 
-	skipOmitempty := checkAndReportInvalidTypes(structName, goFieldName, field.Type, tokenPos, pass)
+	case omitzero:
+		skipOmitzero := checkAndReportInvalidTypesForOmitzero(structName, goFieldName, field.Type, tokenPos, pass)
+		if !skipOmitzero {
+			const msg = `the %q field in struct %q uses "omitzero"; remove "omitzero", as it is only allowed with structs, maps, and slices`
+			pass.Reportf(tokenPos, msg, goFieldName, structName)
+		}
 
-	if !skipOmitempty {
-		const msg = `change the %q field type to %q in the struct %q because its tag uses "omitempty"`
-		pass.Reportf(tokenPos, msg, goFieldName, "*"+exprToString(field.Type), structName)
+	case omitempty:
+		skipOmitempty := checkAndReportInvalidTypes(structName, goFieldName, field.Type, tokenPos, pass)
+		if !skipOmitempty {
+			const msg = `change the %q field type to %q in the struct %q because its tag uses "omitempty"`
+			pass.Reportf(tokenPos, msg, goFieldName, "*"+exprToString(field.Type), structName)
+		}
 	}
 }
 

tools/structfield/testdata/src/has-warnings/main.go

@@ -22,6 +22,18 @@ type JSONFieldType struct {
 	PointerToSliceOfPointerStructs *[]*Struct         `json:"pointer_to_slice_of_pointer_structs,omitempty"` // want `change the "PointerToSliceOfPointerStructs" field type to "\[\]\*Struct" in the struct "JSONFieldType"`
 	PointerToMap                   *map[string]string `json:"pointer_to_map,omitempty"`                      // want `change the "PointerToMap" field type to "map\[string\]string" in the struct "JSONFieldType"`
 	SliceOfInts                    []*int             `json:"slice_of_ints,omitempty"`                       // want `change the "SliceOfInts" field type to "\[\]int" in the struct "JSONFieldType"`
+
+	Count                              int        `json:"count,omitzero"`                                    // want `the "Count" field in struct "JSONFieldType" uses "omitzero" with a primitive type; remove "omitzero", as it is only allowed with structs, maps, and slices`
+	Size                               *int       `json:"size,omitzero"`                                     // want `the "Size" field in struct "JSONFieldType" uses "omitzero" with a primitive type; remove "omitzero" and use only "omitempty" for pointer primitive types`
+	PointerToSliceOfStringsZero        *[]string  `json:"pointer_to_slice_of_strings_zero,omitzero"`         // want `change the "PointerToSliceOfStringsZero" field type to "\[\]string" in the struct "JSONFieldType"`
+	PointerToSliceOfStructsZero        *[]Struct  `json:"pointer_to_slice_of_structs_zero,omitzero"`         // want `change the "PointerToSliceOfStructsZero" field type to "\[\]\*Struct" in the struct "JSONFieldType"`
+	PointerToSliceOfPointerStructsZero *[]*Struct `json:"pointer_to_slice_of_pointer_structs_zero,omitzero"` // want `change the "PointerToSliceOfPointerStructsZero" field type to "\[\]\*Struct" in the struct "JSONFieldType"`
+	PointerSliceInt                    *[]int     `json:"pointer_slice_int,omitempty"`                       // want `change the "PointerSliceInt" field type to "\[\]int" in the struct "JSONFieldType"`
+	AnyZero                            any        `json:"any_zero,omitzero"`                                 // want `the "AnyZero" field in struct "JSONFieldType" uses "omitzero"; remove "omitzero", as it is only allowed with structs, maps, and slices`
+
+	AnyBoth              any     `json:"any_both,omitempty,omitzero"`                // want `the "AnyBoth" field in struct "JSONFieldType" uses "omitzero"; remove "omitzero", as it is only allowed with structs, maps, and slices`
+	NonPointerStructBoth Struct  `json:"non_pointer_struct_both,omitempty,omitzero"` // want `change the "NonPointerStructBoth" field type to "\*Struct" in the struct "JSONFieldType" because its tag uses "omitempty"`
+	PointerStringBoth    *string `json:"pointer_string_both,omitempty,omitzero"`     // want `the "PointerStringBoth" field in struct "JSONFieldType" uses "omitzero" with a primitive type; remove "omitzero" and use only "omitempty" for pointer primitive types`
 }
 
 type Struct struct{}
@@ -34,4 +46,7 @@ type URLFieldType struct {
 	Page          string `url:"page,omitempty"`          // want `change the "Page" field type to "\*string" in the struct "URLFieldType" because its tag uses "omitempty"`
 	PerPage       int    `url:"per_page,omitempty"`      // want `change the "PerPage" field type to "\*int" in the struct "URLFieldType" because its tag uses "omitempty"`
 	Participating bool   `url:"participating,omitempty"` // want `change the "Participating" field type to "\*bool" in the struct "URLFieldType" because its tag uses "omitempty"`
+
+	PerPageZeros []int `url:"per_page_zeros,omitzero"`          // want `the "PerPageZeros" field in struct "URLFieldType" uses unsupported omitzero tag for URL tags`
+	PerPageBoth  *int  `url:"per_page_both,omitempty,omitzero"` // want `the "PerPageBoth" field in struct "URLFieldType" uses unsupported omitzero tag for URL tags`
 }

tools/structfield/testdata/src/no-warnings/main.go

@@ -27,6 +27,20 @@ type JSONFieldType struct {
 	Exception             string            `json:"exception,omitempty"`
 	Value                 any               `json:"value,omitempty"`
 	SliceOfPointerStructs []*Struct         `json:"slice_of_pointer_structs,omitempty"`
+
+	SliceOfStrings               []string        `json:"slice_of_strings,omitzero"`
+	SliceOfPointerInts           []*int          `json:"slice_of_pointer_ints,omitzero"`
+	MapOfStringToInt             map[string]int  `json:"map_of_string_to_int,omitzero"`
+	MapOfPointerStringToInt      *map[string]int `json:"map_of_pointer_string_to_int,omitzero"`
+	StructField                  Struct          `json:"struct_field,omitzero"`
+	PointerStructField           *Struct         `json:"pointer_struct_field,omitzero"`
+	SliceOfPointerStructsZero    []*Struct       `json:"slice_of_pointer_structs_zero,omitzero"`
+	SliceOfNonPointerStructsZero []Struct        `json:"slice_of_non_pointer_structs_zero,omitzero"`
+
+	SliceOfStringsBoth        []string       `json:"slice_of_strings_both,omitzero,omitempty"`
+	MapOfStringToIntBoth      map[string]int `json:"map_of_string_to_int_both,omitzero,omitempty"`
+	SliceOfPointerStructsBoth []*Struct      `json:"slice_of_pointer_structs_both,omitzero,omitempty"`
+	StructFieldBoth           *Struct        `json:"struct_field_both,omitzero,omitempty"`
 }
 
 type URLFieldName struct {