Invoke the Deref function as needed for the function arguments.

checker/checker.go

@@ -1044,7 +1044,7 @@ func (v *checker) checkArguments(
 			continue
 		}
 
-		if !t.AssignableTo(in) && kind(t) != reflect.Interface {
+		if !(t.AssignableTo(in) || deref.Type(t).AssignableTo(in)) && kind(t) != reflect.Interface {
 			return anyType, &file.Error{
 				Location: arg.Location(),
 				Message:  fmt.Sprintf("cannot use %v as argument (type %v) to call %v ", t, in, name),

compiler/compiler.go

@@ -592,8 +592,8 @@ func (c *compiler) BinaryNode(node *ast.BinaryNode) {
 }
 
 func (c *compiler) equalBinaryNode(node *ast.BinaryNode) {
-	l := kind(node.Left)
-	r := kind(node.Right)
+	l := kind(node.Left.Type())
+	r := kind(node.Right.Type())
 
 	leftIsSimple := isSimpleType(node.Left)
 	rightIsSimple := isSimpleType(node.Right)
@@ -727,9 +727,44 @@ func (c *compiler) SliceNode(node *ast.SliceNode) {
 }
 
 func (c *compiler) CallNode(node *ast.CallNode) {
-	for _, arg := range node.Arguments {
-		c.compile(arg)
+	fn := node.Callee.Type()
+	if kind(fn) == reflect.Func {
+		fnInOffset := 0
+		fnNumIn := fn.NumIn()
+		switch callee := node.Callee.(type) {
+		case *ast.MemberNode:
+			if prop, ok := callee.Property.(*ast.StringNode); ok {
+				if _, ok = callee.Node.Type().MethodByName(prop.Value); ok && callee.Node.Type().Kind() != reflect.Interface {
+					fnInOffset = 1
+					fnNumIn--
+				}
+			}
+		case *ast.IdentifierNode:
+			if t, ok := c.config.Types[callee.Value]; ok && t.Method {
+				fnInOffset = 1
+				fnNumIn--
+			}
+		}
+		for i, arg := range node.Arguments {
+			c.compile(arg)
+			if k := kind(arg.Type()); k == reflect.Ptr || k == reflect.Interface {
+				var in reflect.Type
+				if fn.IsVariadic() && i >= fnNumIn-1 {
+					in = fn.In(fn.NumIn() - 1).Elem()
+				} else {
+					in = fn.In(i + fnInOffset)
+				}
+				if k = kind(in); k != reflect.Ptr && k != reflect.Interface {
+					c.emit(OpDeref)
+				}
+			}
+		}
+	} else {
+		for _, arg := range node.Arguments {
+			c.compile(arg)
+		}
 	}
+
 	if ident, ok := node.Callee.(*ast.IdentifierNode); ok {
 		if c.config != nil {
 			if fn, ok := c.config.Functions[ident.Value]; ok {
@@ -1162,7 +1197,7 @@ func (c *compiler) PairNode(node *ast.PairNode) {
 }
 
 func (c *compiler) derefInNeeded(node ast.Node) {
-	switch kind(node) {
+	switch kind(node.Type()) {
 	case reflect.Ptr, reflect.Interface:
 		c.emit(OpDeref)
 	}
@@ -1181,8 +1216,7 @@ func (c *compiler) optimize() {
 	}
 }
 
-func kind(node ast.Node) reflect.Kind {
-	t := node.Type()
+func kind(t reflect.Type) reflect.Kind {
 	if t == nil {
 		return reflect.Invalid
 	}

test/deref/deref_test.go

@@ -3,6 +3,7 @@ package deref_test
 import (
 	"context"
 	"testing"
+	"time"
 
 	"github.com/expr-lang/expr/internal/testify/assert"
 	"github.com/expr-lang/expr/internal/testify/require"
@@ -253,3 +254,69 @@ func TestDeref_fetch_from_interface_mix_pointer(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, "waldo", res)
 }
+
+func TestDeref_func_args(t *testing.T) {
+	i := 20
+	env := map[string]any{
+		"var": &i,
+		"fn": func(p int) int {
+			return p + 1
+		},
+	}
+
+	program, err := expr.Compile(`fn(var) + fn(var + 0)`, expr.Env(env))
+	require.NoError(t, err)
+
+	out, err := expr.Run(program, env)
+	require.NoError(t, err)
+	require.Equal(t, 42, out)
+}
+
+func TestDeref_struct_func_args(t *testing.T) {
+	n, _ := time.Parse(time.RFC3339, "2024-05-12T18:30:00+00:00")
+	duration := 30 * time.Minute
+	env := map[string]any{
+		"time":     n,
+		"duration": &duration,
+	}
+
+	program, err := expr.Compile(`time.Add(duration).Format('2006-01-02T15:04:05Z07:00')`, expr.Env(env))
+	require.NoError(t, err)
+
+	out, err := expr.Run(program, env)
+	require.NoError(t, err)
+	require.Equal(t, "2024-05-12T19:00:00Z", out)
+}
+
+func TestDeref_ignore_func_args(t *testing.T) {
+	f := foo(1)
+	env := map[string]any{
+		"foo": &f,
+		"fn": func(f *foo) int {
+			return f.Bar()
+		},
+	}
+
+	program, err := expr.Compile(`fn(foo)`, expr.Env(env))
+	require.NoError(t, err)
+
+	out, err := expr.Run(program, env)
+	require.NoError(t, err)
+	require.Equal(t, 42, out)
+}
+
+func TestDeref_ignore_struct_func_args(t *testing.T) {
+	n := time.Now()
+	location, _ := time.LoadLocation("UTC")
+	env := map[string]any{
+		"time":     n,
+		"location": location,
+	}
+
+	program, err := expr.Compile(`time.In(location).Location().String()`, expr.Env(env))
+	require.NoError(t, err)
+
+	out, err := expr.Run(program, env)
+	require.NoError(t, err)
+	require.Equal(t, "UTC", out)
+}