cgen: fix array filter with an inline closure (fix #16770) (#16772)

vlib/v/gen/c/array.v

@@ -331,6 +331,19 @@ fn (mut g Gen) array_init_with_fields(node ast.ArrayInit, elem_type Type, is_amp
 	}
 }
 
+fn (mut g Gen) write_closure_fn(mut expr ast.AnonFn) {
+	var := g.new_tmp_var()
+	line := g.go_before_stmt(0).trim_space()
+	g.empty_line = true
+	fn_ptr_name := g.fn_var_signature(expr.decl.return_type, expr.decl.params.map(it.typ),
+		var)
+	g.write('${fn_ptr_name} = ')
+	g.gen_anon_fn(mut expr)
+	g.writeln(';')
+	g.write(line)
+	g.write('${var}(it)')
+}
+
 // `nums.map(it % 2 == 0)`
 fn (mut g Gen) gen_array_map(node ast.CallExpr) {
 	g.inside_lambda = true
@@ -364,8 +377,12 @@ fn (mut g Gen) gen_array_map(node ast.CallExpr) {
 	match mut expr {
 		ast.AnonFn {
 			g.write('${ret_elem_type} ti = ')
-			g.gen_anon_fn_decl(mut expr)
-			g.write('${expr.decl.name}(it)')
+			if expr.inherited_vars.len > 0 {
+				g.write_closure_fn(mut expr)
+			} else {
+				g.gen_anon_fn_decl(mut expr)
+				g.write('${expr.decl.name}(it)')
+			}
 		}
 		ast.Ident {
 			g.write('${ret_elem_type} ti = ')
@@ -559,8 +576,12 @@ fn (mut g Gen) gen_array_filter(node ast.CallExpr) {
 	match mut expr {
 		ast.AnonFn {
 			g.write('if (')
-			g.gen_anon_fn_decl(mut expr)
-			g.write('${expr.decl.name}(it)')
+			if expr.inherited_vars.len > 0 {
+				g.write_closure_fn(mut expr)
+			} else {
+				g.gen_anon_fn_decl(mut expr)
+				g.write('${expr.decl.name}(it)')
+			}
 		}
 		ast.Ident {
 			g.write('if (')
@@ -918,8 +939,12 @@ fn (mut g Gen) gen_array_any(node ast.CallExpr) {
 	match mut expr {
 		ast.AnonFn {
 			g.write('if (')
-			g.gen_anon_fn_decl(mut expr)
-			g.write('${expr.decl.name}(it)')
+			if expr.inherited_vars.len > 0 {
+				g.write_closure_fn(mut expr)
+			} else {
+				g.gen_anon_fn_decl(mut expr)
+				g.write('${expr.decl.name}(it)')
+			}
 		}
 		ast.Ident {
 			g.write('if (')
@@ -994,8 +1019,12 @@ fn (mut g Gen) gen_array_all(node ast.CallExpr) {
 	match mut expr {
 		ast.AnonFn {
 			g.write('if (!(')
-			g.gen_anon_fn_decl(mut expr)
-			g.write('${expr.decl.name}(it)')
+			if expr.inherited_vars.len > 0 {
+				g.write_closure_fn(mut expr)
+			} else {
+				g.gen_anon_fn_decl(mut expr)
+				g.write('${expr.decl.name}(it)')
+			}
 		}
 		ast.Ident {
 			g.write('if (!(')

vlib/v/tests/array_filter_using_direct_closure_test.v

@@ -0,0 +1,42 @@
+struct File {
+	name   string
+	typ    string
+	is_dir bool
+}
+
+fn filter(all_files []File, interested_file File) []File {
+	println(interested_file)
+	return all_files.filter(fn [interested_file] (f File) bool {
+		println(interested_file)
+		return true
+	})
+}
+
+fn test_array_filter_using_direct_closure() {
+	filenames := ['one', 'two', 'three']
+	files := filenames.map(fn (f string) File {
+		return File{
+			name: f
+			typ: if f == 'one' {
+				'file'
+			} else {
+				'dir'
+			}
+			is_dir: if f == 'one' {
+				false
+			} else {
+				true
+			}
+		}
+	})
+
+	ret := filter(files, files[0])
+	println(ret)
+	assert ret.len == 3
+	assert ret[0].name == 'one'
+	assert ret[0].typ == 'file'
+	assert ret[1].name == 'two'
+	assert ret[1].typ == 'dir'
+	assert ret[2].name == 'three'
+	assert ret[2].typ == 'dir'
+}