1 files changed, 79 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/apidiff/messageset.go b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/apidiff/messageset.go
new file mode 100644
index 0000000..1354790
--- /dev/null
+++ b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/apidiff/messageset.go
@@ -0,0 +1,79 @@
+// TODO: show that two-non-empty dotjoin can happen, by using an anon struct as a field type
+// TODO: don't report removed/changed methods for both value and pointer method sets?
+
+package apidiff
+
+import (
+	"fmt"
+	"go/types"
+	"sort"
+	"strings"
+)
+
+// There can be at most one message for each object or part thereof.
+// Parts include interface methods and struct fields.
+//
+// The part thing is necessary. Method (Func) objects have sufficient info, but field
+// Vars do not: they just have a field name and a type, without the enclosing struct.
+type messageSet map[types.Object]map[string]string
+
+// Add a message for obj and part, overwriting a previous message
+// (shouldn't happen).
+// obj is required but part can be empty.
+func (m messageSet) add(obj types.Object, part, msg string) {
+	s := m[obj]
+	if s == nil {
+		s = map[string]string{}
+		m[obj] = s
+	}
+	if f, ok := s[part]; ok && f != msg {
+		fmt.Printf("! second, different message for obj %s, part %q\n", obj, part)
+		fmt.Printf("  first:  %s\n", f)
+		fmt.Printf("  second: %s\n", msg)
+	}
+	s[part] = msg
+}
+
+func (m messageSet) collect() []string {
+	var s []string
+	for obj, parts := range m {
+		// Format each object name relative to its own package.
+		objstring := objectString(obj)
+		for part, msg := range parts {
+			var p string
+
+			if strings.HasPrefix(part, ",") {
+				p = objstring + part
+			} else {
+				p = dotjoin(objstring, part)
+			}
+			s = append(s, p+": "+msg)
+		}
+	}
+	sort.Strings(s)
+	return s
+}
+
+func objectString(obj types.Object) string {
+	if f, ok := obj.(*types.Func); ok {
+		sig := f.Type().(*types.Signature)
+		if recv := sig.Recv(); recv != nil {
+			tn := types.TypeString(recv.Type(), types.RelativeTo(obj.Pkg()))
+			if tn[0] == '*' {
+				tn = "(" + tn + ")"
+			}
+			return fmt.Sprintf("%s.%s", tn, obj.Name())
+		}
+	}
+	return obj.Name()
+}
+
+func dotjoin(s1, s2 string) string {
+	if s1 == "" {
+		return s2
+	}
+	if s2 == "" {
+		return s1
+	}
+	return s1 + "." + s2
+}