use property id as a key

benchmark                         old ns/op     new ns/op     delta
BenchmarkAllocProperty/props0     83.3          83.4          +0.12%
BenchmarkAllocProperty/props1     296           254           -14.19%
BenchmarkAllocProperty/props2     606           492           -18.81%
BenchmarkAllocProperty/props3     1009          804           -20.32%
BenchmarkAllocProperty/props4     1439          1112          -22.72%
BenchmarkAllocProperty/props5     1952          1503          -23.00%
BenchmarkAllocProperty/props6     2486          1866          -24.94%
BenchmarkAllocProperty/props7     3115          2322          -25.46%
BenchmarkAllocProperty/props8     3751          2733          -27.14%

benchmark                         old allocs     new allocs     delta
BenchmarkAllocProperty/props0     1              1              +0.00%
BenchmarkAllocProperty/props1     4              4              +0.00%
BenchmarkAllocProperty/props2     7              7              +0.00%
BenchmarkAllocProperty/props3     10             10             +0.00%
BenchmarkAllocProperty/props4     13             13             +0.00%
BenchmarkAllocProperty/props5     16             16             +0.00%
BenchmarkAllocProperty/props6     19             19             +0.00%
BenchmarkAllocProperty/props7     22             22             +0.00%
BenchmarkAllocProperty/props8     25             25             +0.00%

benchmark                         old bytes     new bytes     delta
BenchmarkAllocProperty/props0     96            96            +0.00%
BenchmarkAllocProperty/props1     592           448           -24.32%
BenchmarkAllocProperty/props2     1088          800           -26.47%
BenchmarkAllocProperty/props3     1584          1152          -27.27%
BenchmarkAllocProperty/props4     2080          1504          -27.69%
BenchmarkAllocProperty/props5     2576          1856          -27.95%
BenchmarkAllocProperty/props6     3072          2208          -28.12%
BenchmarkAllocProperty/props7     3568          2560          -28.25%
BenchmarkAllocProperty/props8     4064          2912          -28.35%

Author: funny-falcon

error.go

@@ -16,7 +16,7 @@ type Error struct {
 	underlying  []error
 	stackTrace  *stackTrace
 	transparent bool
-	properties  map[Property]interface{}
+	properties  map[int64]interface{}
 }
 
 var _ fmt.Formatter = (*Error)(nil)
@@ -29,15 +29,15 @@ func (e *Error) WithProperty(key Property, value interface{}) *Error {
 	errorCopy := *e
 
 	if errorCopy.properties == nil {
-		errorCopy.properties = make(map[Property]interface{}, 1)
+		errorCopy.properties = make(map[int64]interface{}, 1)
 	} else {
-		errorCopy.properties = make(map[Property]interface{}, len(e.properties) + 1)
+		errorCopy.properties = make(map[int64]interface{}, len(e.properties)+1)
 		for k, v := range e.properties {
 			errorCopy.properties[k] = v
 		}
 	}
 
-	errorCopy.properties[key] = value
+	errorCopy.properties[key.id] = value
 	return &errorCopy
 }
 
@@ -47,7 +47,7 @@ func (e *Error) WithProperty(key Property, value interface{}) *Error {
 func (e *Error) WithUnderlyingErrors(errs ...error) *Error {
 	errorCopy := *e
 
-	newUnderying := make([]error, 0, len(e.underlying) + len(errs))
+	newUnderying := make([]error, 0, len(e.underlying)+len(errs))
 	newUnderying = append(newUnderying, e.underlying...)
 
 	for _, err := range errs {
@@ -69,7 +69,7 @@ func (e *Error) WithUnderlyingErrors(errs ...error) *Error {
 func (e *Error) Property(key Property) (interface{}, bool) {
 	cause := e
 	for cause != nil {
-		value, ok := cause.properties[key]
+		value, ok := cause.properties[key.id]
 		if ok {
 			return value, true
 		}