From da04c55bcbb2709417c056c62531de2f434595f2 Mon Sep 17 00:00:00 2001
From: Anton Medvedev <anton@medv.io>
Date: Wed, 28 Aug 2024 23:00:18 +0200
Subject: [PATCH] Add default map value type

---
 checker/checker_test.go  |  2 ++
 checker/nature/nature.go | 28 +++++++++++++++++-----------
 types/types.go           |  2 ++
 3 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/checker/checker_test.go b/checker/checker_test.go
index 602fe4b7..17ec886e 100644
--- a/checker/checker_test.go
+++ b/checker/checker_test.go
@@ -1090,9 +1090,11 @@ func TestCheck_types(t *testing.T) {
 		err  string
 	}{
 		{`unknown`, noerr},
+		{`[unknown + 42, another_unknown + "foo"]`, noerr},
 		{`foo.bar.baz > 0`, `invalid operation: > (mismatched types string and int)`},
 		{`foo.unknown.baz`, `unknown field unknown (1:5)`},
 		{`foo.bar.unknown`, noerr},
+		{`foo.bar.unknown + 42`, `invalid operation: + (mismatched types string and int)`},
 		{`[foo] | map(.unknown)`, `unknown field unknown`},
 		{`[foo] | map(.bar) | filter(.baz)`, `predicate should return boolean (got string)`},
 		{`arr | filter(.value > 0)`, `invalid operation: > (mismatched types string and int)`},
diff --git a/checker/nature/nature.go b/checker/nature/nature.go
index a385521c..2b09353b 100644
--- a/checker/nature/nature.go
+++ b/checker/nature/nature.go
@@ -12,16 +12,17 @@ var (
 )
 
 type Nature struct {
-	Type         reflect.Type      // Type of the value. If nil, then value is unknown.
-	Func         *builtin.Function // Used to pass function type from callee to CallNode.
-	ArrayOf      *Nature           // Elem nature of array type (usually Type is []any, but ArrayOf can be any nature).
-	PredicateOut *Nature           // Out nature of predicate.
-	Fields       map[string]Nature // Fields of map type.
-	Strict       bool              // If map is types.StrictMap.
-	Nil          bool              // If value is nil.
-	Method       bool              // If value retrieved from method. Usually used to determine amount of in arguments.
-	MethodIndex  int               // Index of method in type.
-	FieldIndex   []int             // Index of field in type.
+	Type            reflect.Type      // Type of the value. If nil, then value is unknown.
+	Func            *builtin.Function // Used to pass function type from callee to CallNode.
+	ArrayOf         *Nature           // Elem nature of array type (usually Type is []any, but ArrayOf can be any nature).
+	PredicateOut    *Nature           // Out nature of predicate.
+	Fields          map[string]Nature // Fields of map type.
+	DefaultMapValue *Nature           // Default value of map type.
+	Strict          bool              // If map is types.StrictMap.
+	Nil             bool              // If value is nil.
+	Method          bool              // If value retrieved from method. Usually used to determine amount of in arguments.
+	MethodIndex     int               // Index of method in type.
+	FieldIndex      []int             // Index of field in type.
 }
 
 func (n Nature) String() string {
@@ -54,7 +55,12 @@ func (n Nature) Key() Nature {
 
 func (n Nature) Elem() Nature {
 	switch n.Kind() {
-	case reflect.Map, reflect.Ptr:
+	case reflect.Ptr:
+		return Nature{Type: n.Type.Elem()}
+	case reflect.Map:
+		if n.DefaultMapValue != nil {
+			return *n.DefaultMapValue
+		}
 		return Nature{Type: n.Type.Elem()}
 	case reflect.Array, reflect.Slice:
 		if n.ArrayOf != nil {
diff --git a/types/types.go b/types/types.go
index d10d2fbc..bb1cbe5f 100644
--- a/types/types.go
+++ b/types/types.go
@@ -108,6 +108,8 @@ func (m Map) Nature() Nature {
 	for k, v := range m {
 		if k == Extra {
 			nt.Strict = false
+			natureOfDefaultValue := v.Nature()
+			nt.DefaultMapValue = &natureOfDefaultValue
 			continue
 		}
 		nt.Fields[k] = v.Nature()