From 436ef127307e036285c01ca723e666de881ec4e3 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Fri, 3 Apr 2020 18:49:12 +0200
Subject: [PATCH] cgen: str(): handle empty structs

---
 vlib/v/gen/cgen.v          | 12 +++++++-----
 vlib/v/tests/struct_test.v |  4 ++++
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index f65cabf0f7..d63baf476a 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -49,7 +49,7 @@ mut:
 	assign_op      token.Kind // *=, =, etc (for array_set)
 	defer_stmts    []ast.DeferStmt
 	defer_ifdef    string
-	str_types      []int // types that need automatic str() generation
+	str_types      []string// types that need automatic str() generation
 	threaded_fns   []string // for generating unique wrapper types and fns for `go xxx()`
 }
 
@@ -2423,12 +2423,12 @@ fn (g mut Gen) fn_call(node ast.CallExpr) {
 		typ := node.args[0].typ
 		mut styp := g.typ(typ)
 		sym := g.table.get_type_symbol(typ)
-		if !sym.has_method('str') && !(int(typ) in g.str_types) {
+		if !sym.has_method('str') && !(styp in g.str_types) {
 			// Generate an automatic str() method if this type doesn't have it already
 			if table.type_is_ptr(typ) {
 				styp = styp.replace('*', '')
 			}
-			g.str_types << typ
+			g.str_types << styp
 			g.gen_str_for_type(sym, styp)
 		}
 		if g.autofree && !table.type_is_optional(typ) {
@@ -2882,9 +2882,11 @@ fn (g mut Gen) gen_str_for_type(sym table.TypeSymbol, styp string) {
 	for field in info.fields {
 		fmt := type_to_fmt(field.typ)
 		g.definitions.write('\t$field.name: $fmt\\n')
-
 	}
-	g.definitions.write('\\n}", ')
+	g.definitions.write('\\n}"')
+	if info.fields.len > 0 {
+		g.definitions.write(', ')
+	}
 	for i, field in info.fields {
 		g.definitions.write('a.' + field.name)
 		if field.typ == table.string_type {
diff --git a/vlib/v/tests/struct_test.v b/vlib/v/tests/struct_test.v
index 312e79038a..8ce1d08ee1 100644
--- a/vlib/v/tests/struct_test.v
+++ b/vlib/v/tests/struct_test.v
@@ -59,7 +59,11 @@ struct ReservedKeywords {
 
 fn test_empty_struct() {
 	d := &Empty{}
+	d2 := Empty{}
+	println('&empty:')
 	println(d) // != voidptr(0)
+	println('empty:')
+	println(d2) // empty struct print
 	println(sizeof(Empty)) // == 0
 }