From 92290849d571de15c0a625f7fc417ee0ca36f6c4 Mon Sep 17 00:00:00 2001
From: Tom <github@junk1tm.me>
Date: Sat, 4 Feb 2023 19:44:58 +0400
Subject: [PATCH] fix: embedded types false positive (#15)

---
 musttag.go                  |  6 ++-
 testdata/src/tests/tests.go | 79 +++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 1 deletion(-)

diff --git a/musttag.go b/musttag.go
index de7f050..a58dc1c 100644
--- a/musttag.go
+++ b/musttag.go
@@ -206,7 +206,11 @@ func checkStruct(s *types.Struct, tag string, pos *token.Pos) (ok bool) {
 
 		st := reflect.StructTag(s.Tag(i))
 		if _, ok := st.Lookup(tag); !ok {
-			return false
+			// it's ok for embedded types not to be tagged,
+			// see https://github.com/junk1tm/musttag/issues/12
+			if !s.Field(i).Embedded() {
+				return false
+			}
 		}
 
 		// check if the field is a nested struct.
diff --git a/testdata/src/tests/tests.go b/testdata/src/tests/tests.go
index 6d72a0d..7e5b806 100644
--- a/testdata/src/tests/tests.go
+++ b/testdata/src/tests/tests.go
@@ -285,6 +285,85 @@ func nestedAnonymousType() {
 	custom.Unmarshal(nil, &x)
 }
 
+// embedded types should not be reported.
+func embeddedType() {
+    type Y struct { /* want
+        `\Qjson.Marshal`
+        `\Qjson.MarshalIndent`
+        `\Qjson.Unmarshal`
+        `\Qjson.Encoder.Encode`
+        `\Qjson.Decoder.Decode`
+
+        `\Qxml.Marshal`
+        `\Qxml.MarshalIndent`
+        `\Qxml.Unmarshal`
+        `\Qxml.Encoder.Encode`
+        `\Qxml.Decoder.Decode`
+        `\Qxml.Encoder.EncodeElement`
+        `\Qxml.Decoder.DecodeElement`
+
+        `\Qyaml.v3.Marshal`
+        `\Qyaml.v3.Unmarshal`
+        `\Qyaml.v3.Encoder.Encode`
+        `\Qyaml.v3.Decoder.Decode`
+
+        `\Qtoml.Unmarshal`
+        `\Qtoml.Decode`
+        `\Qtoml.DecodeFS`
+        `\Qtoml.DecodeFile`
+        `\Qtoml.Encoder.Encode`
+        `\Qtoml.Decoder.Decode`
+
+        `\Qmapstructure.Decode`
+        `\Qmapstructure.DecodeMetadata`
+        `\Qmapstructure.WeakDecode`
+        `\Qmapstructure.WeakDecodeMetadata`
+
+        `\Qcustom.Marshal`
+        `\Qcustom.Unmarshal` */
+        NoTag int
+    }
+
+    var x struct {
+        Y
+        Z int `json:"z" xml:"z" yaml:"z" toml:"z" mapstructure:"z" custom:"z"`
+    }
+
+    json.Marshal(x)
+    json.MarshalIndent(x, "", "")
+    json.Unmarshal(nil, &x)
+    json.NewEncoder(nil).Encode(x)
+    json.NewDecoder(nil).Decode(&x)
+
+    xml.Marshal(x)
+    xml.MarshalIndent(x, "", "")
+    xml.Unmarshal(nil, &x)
+    xml.NewEncoder(nil).Encode(x)
+    xml.NewDecoder(nil).Decode(&x)
+    xml.NewEncoder(nil).EncodeElement(x, xmlSE)
+    xml.NewDecoder(nil).DecodeElement(&x, &xmlSE)
+
+    yaml.Marshal(x)
+    yaml.Unmarshal(nil, &x)
+    yaml.NewEncoder(nil).Encode(x)
+    yaml.NewDecoder(nil).Decode(&x)
+
+    toml.Unmarshal(nil, &x)
+    toml.Decode("", &x)
+    toml.DecodeFS(nil, "", &x)
+    toml.DecodeFile("", &x)
+    toml.NewEncoder(nil).Encode(x)
+    toml.NewDecoder(nil).Decode(&x)
+
+    mapstructure.Decode(nil, &x)
+    mapstructure.DecodeMetadata(nil, &x, nil)
+    mapstructure.WeakDecode(nil, &x)
+    mapstructure.WeakDecodeMetadata(nil, &x, nil)
+
+    custom.Marshal(x)
+    custom.Unmarshal(nil, &x)
+}
+
 // all good, nothing to report.
 func typeWithAllTags() {
 	var x struct {