From 02965e753ea3348b295ddc78cfc368066d1196c2 Mon Sep 17 00:00:00 2001
From: joe-conigliaro <joe@vlang.io>
Date: Wed, 30 Dec 2020 02:14:08 +1100
Subject: [PATCH] all: re-implement variadics using arrays & implement array
 decomposition to varg (#7689)

---
 vlib/v/ast/ast.v                              |  18 ++-
 vlib/v/checker/check_types.v                  |  14 ++
 vlib/v/checker/checker.v                      |  33 ++--
 vlib/v/checker/tests/fn_args.out              |   6 +-
 .../checker/tests/function_wrong_arg_type.out |   2 +-
 vlib/v/checker/tests/is_type_not_exist.out    |   2 +-
 .../v/checker/tests/method_wrong_arg_type.out |   2 +-
 .../tests/non_matching_functional_args.out    |   4 +-
 vlib/v/fmt/fmt.v                              |   3 +
 vlib/v/gen/auto_str_methods.v                 |  25 ---
 vlib/v/gen/cgen.v                             |  41 +----
 vlib/v/gen/cheaders.v                         |   2 -
 vlib/v/gen/fn.v                               |  49 +++---
 vlib/v/gen/js/js.v                            | 152 +++++++++++-------
 vlib/v/gen/str.v                              |   2 -
 vlib/v/parser/fn.v                            |  11 +-
 vlib/v/table/table.v                          |   4 +-
 vlib/v/table/types.v                          |  10 +-
 vlib/v/tests/fn_variadic_test.v               |   9 +-
 vlib/x/openssl/openssl.v                      |   4 +-
 20 files changed, 210 insertions(+), 183 deletions(-)

diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index c7811362a2..bdecbdfc5a 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -9,9 +9,9 @@ import v.errors
 
 pub type TypeDecl = AliasTypeDecl | FnTypeDecl | SumTypeDecl
 
-pub type Expr = AnonFn | ArrayInit | AsCast | Assoc | AtExpr | BoolLiteral | CTempVar |
-	CallExpr | CastExpr | ChanInit | CharLiteral | Comment | ComptimeCall | ConcatExpr | EnumVal |
-	FloatLiteral | Ident | IfExpr | IfGuardExpr | IndexExpr | InfixExpr | IntegerLiteral |
+pub type Expr = AnonFn | ArrayDecompose | ArrayInit | AsCast | Assoc | AtExpr | BoolLiteral |
+	CTempVar | CallExpr | CastExpr | ChanInit | CharLiteral | Comment | ComptimeCall | ConcatExpr |
+	EnumVal | FloatLiteral | Ident | IfExpr | IfGuardExpr | IndexExpr | InfixExpr | IntegerLiteral |
 	Likely | LockExpr | MapInit | MatchExpr | None | OrExpr | ParExpr | PostfixExpr | PrefixExpr |
 	RangeExpr | SelectExpr | SelectorExpr | SizeOf | SqlExpr | StringInterLiteral | StringLiteral |
 	StructInit | Type | TypeOf | UnsafeExpr
@@ -890,6 +890,15 @@ pub mut:
 	typ            table.Type // array type
 }
 
+pub struct ArrayDecompose {
+pub:
+	expr      Expr
+	pos       token.Position
+pub mut:
+	expr_type table.Type
+	arg_type  table.Type
+}
+
 pub struct ChanInit {
 pub:
 	pos       token.Position
@@ -1129,6 +1138,9 @@ pub fn (expr Expr) position() token.Position {
 		ArrayInit, AsCast, Assoc, AtExpr, BoolLiteral, CallExpr, CastExpr, ChanInit, CharLiteral, ConcatExpr, Comment, EnumVal, FloatLiteral, Ident, IfExpr, IndexExpr, IntegerLiteral, Likely, LockExpr, MapInit, MatchExpr, None, OrExpr, ParExpr, PostfixExpr, PrefixExpr, RangeExpr, SelectExpr, SelectorExpr, SizeOf, SqlExpr, StringInterLiteral, StringLiteral, StructInit, Type, TypeOf, UnsafeExpr {
 			return expr.pos
 		}
+		ArrayDecompose {
+			return expr.pos
+		}
 		IfGuardExpr {
 			return expr.expr.position()
 		}
diff --git a/vlib/v/checker/check_types.v b/vlib/v/checker/check_types.v
index 5d686cb468..bab606b2ac 100644
--- a/vlib/v/checker/check_types.v
+++ b/vlib/v/checker/check_types.v
@@ -7,6 +7,20 @@ import v.table
 import v.token
 import v.ast
 
+pub fn (mut c Checker) check_expected_call_arg(got table.Type, expected_ table.Type) ? {
+	mut expected := expected_
+	// variadic
+	if expected.has_flag(.variadic) {
+		exp_type_sym := c.table.get_type_symbol(expected_)
+		exp_info := exp_type_sym.info as table.Array
+		expected = exp_info.elem_type
+	}
+	if c.check_types(got, expected) {
+		return
+	}
+	return error('cannot use `${c.table.type_to_str(got.clear_flag(.variadic))}` as `${c.table.type_to_str(expected.clear_flag(.variadic))}`')
+}
+
 pub fn (mut c Checker) check_basic(got table.Type, expected table.Type) bool {
 	if got == expected {
 		return true
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 6184af75e3..87f7afb20b 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1333,21 +1333,16 @@ pub fn (mut c Checker) call_method(mut call_expr ast.CallExpr) table.Type {
 				c.type_implements(got_arg_typ, exp_arg_typ, arg.expr.position())
 				continue
 			}
-			if !c.check_types(got_arg_typ, exp_arg_typ) {
-				got_arg_sym := c.table.get_type_symbol(got_arg_typ)
+			c.check_expected_call_arg(got_arg_typ, exp_arg_typ) or {
 				// str method, allow type with str method if fn arg is string
-				// if exp_arg_sym.kind == .string && got_arg_sym.has_method('str') {
+				// Passing an int or a string array produces a c error here
+				// Deleting this condition results in propper V error messages
+				// if arg_typ_sym.kind == .string && typ_sym.has_method('str') {
 				// continue
 				// }
-				// same ancestor? let it be
-				if exp_arg_sym.parent_idx == got_arg_sym.parent_idx {
-					if got_arg_sym.parent_idx != 0 {
-						continue
-					}
-				}
 				if got_arg_typ != table.void_type {
-					c.error('cannot use type `$got_arg_sym.name` as type `$exp_arg_sym.name` in argument ${i +
-						1} to `${left_type_sym.name}.$method_name`', call_expr.pos)
+					c.error('$err in argument ${i + 1} to `${left_type_sym.name}.$method_name`',
+						call_expr.pos)
 				}
 			}
 			param := if method.is_variadic && i >= method.params.len - 1 { method.params[method.params.len -
@@ -1660,7 +1655,7 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 			c.type_implements(typ, arg.typ, call_arg.expr.position())
 			continue
 		}
-		c.check_expected(typ, arg.typ) or {
+		c.check_expected_call_arg(typ, arg.typ) or {
 			// str method, allow type with str method if fn arg is string
 			// Passing an int or a string array produces a c error here
 			// Deleting this condition results in propper V error messages
@@ -1673,7 +1668,7 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 			if f.is_generic {
 				continue
 			}
-			c.error('invalid argument ${i + 1} to `$fn_name`: $err', call_arg.pos)
+			c.error('$err in argument ${i + 1} to `$fn_name`', call_arg.pos)
 		}
 	}
 	if f.is_generic && call_expr.generic_type == table.void_type {
@@ -2981,6 +2976,18 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 			c.cur_fn = keep_fn
 			return node.typ
 		}
+		ast.ArrayDecompose {
+			typ := c.expr(node.expr)
+			type_sym := c.table.get_type_symbol(typ)
+			if type_sym.kind != .array {
+				c.error('expected array', node.pos)
+			}
+			array_info := type_sym.info as table.Array
+			elem_type := array_info.elem_type.set_flag(.variadic)
+			node.expr_type = typ
+			node.arg_type = elem_type
+			return elem_type
+		}
 		ast.ArrayInit {
 			return c.array_init(mut node)
 		}
diff --git a/vlib/v/checker/tests/fn_args.out b/vlib/v/checker/tests/fn_args.out
index 904eb3483f..563aae8251 100644
--- a/vlib/v/checker/tests/fn_args.out
+++ b/vlib/v/checker/tests/fn_args.out
@@ -1,17 +1,17 @@
-vlib/v/checker/tests/fn_args.vv:6:5: error: invalid argument 1 to `ptr`: expected `byte`, not `&int`
+vlib/v/checker/tests/fn_args.vv:6:5: error: cannot use `&int` as `byte` in argument 1 to `ptr`
     4 |
     5 | v := 4
     6 | ptr(&v)
       |     ~~
     7 | arr([5]!!)
     8 | fun(fn(i &int){})
-vlib/v/checker/tests/fn_args.vv:7:5: error: invalid argument 1 to `arr`: expected `[]int`, not `[1]int`
+vlib/v/checker/tests/fn_args.vv:7:5: error: cannot use `[1]int` as `[]int` in argument 1 to `arr`
     5 | v := 4
     6 | ptr(&v)
     7 | arr([5]!!)
       |     ~~~~~
     8 | fun(fn(i &int){})
-vlib/v/checker/tests/fn_args.vv:8:5: error: invalid argument 1 to `fun`: expected `fn (int)`, not `fn (&int)`
+vlib/v/checker/tests/fn_args.vv:8:5: error: cannot use `fn (&int)` as `fn (int)` in argument 1 to `fun`
     6 | ptr(&v)
     7 | arr([5]!!)
     8 | fun(fn(i &int){})
diff --git a/vlib/v/checker/tests/function_wrong_arg_type.out b/vlib/v/checker/tests/function_wrong_arg_type.out
index 2e8af639cc..07e4fc856c 100644
--- a/vlib/v/checker/tests/function_wrong_arg_type.out
+++ b/vlib/v/checker/tests/function_wrong_arg_type.out
@@ -1,4 +1,4 @@
-vlib/v/checker/tests/function_wrong_arg_type.vv:7:9: error: invalid argument 1 to `f`: expected `int`, not `f64`
+vlib/v/checker/tests/function_wrong_arg_type.vv:7:9: error: cannot use `f64` as `int` in argument 1 to `f`
     5 | fn main() {
     6 |     a := 12.3
     7 |     q := f(a)
diff --git a/vlib/v/checker/tests/is_type_not_exist.out b/vlib/v/checker/tests/is_type_not_exist.out
index 84c7c0c2ec..e597f95c7a 100644
--- a/vlib/v/checker/tests/is_type_not_exist.out
+++ b/vlib/v/checker/tests/is_type_not_exist.out
@@ -1,4 +1,4 @@
-vlib/v/checker/tests/is_type_not_exist.vv:4:25: error: invalid argument 1 to `fn_with_sum_type_param`: expected `Integer`, not `any_int`
+vlib/v/checker/tests/is_type_not_exist.vv:4:25: error: cannot use `any_int` as `Integer` in argument 1 to `fn_with_sum_type_param`
     2 |
     3 | fn main() {
     4 |     fn_with_sum_type_param(1)
diff --git a/vlib/v/checker/tests/method_wrong_arg_type.out b/vlib/v/checker/tests/method_wrong_arg_type.out
index bd42ed3630..6d04f558fb 100644
--- a/vlib/v/checker/tests/method_wrong_arg_type.out
+++ b/vlib/v/checker/tests/method_wrong_arg_type.out
@@ -1,4 +1,4 @@
-vlib/v/checker/tests/method_wrong_arg_type.vv:8:4: error: cannot use type `MyEnum` as type `string` in argument 1 to `Sss.info` 
+vlib/v/checker/tests/method_wrong_arg_type.vv:8:4: error: cannot use `MyEnum` as `string` in argument 1 to `Sss.info`
     6 |     e := MyEnum.x
     7 |     s := Sss{}
     8 |     s.info(e)
diff --git a/vlib/v/checker/tests/non_matching_functional_args.out b/vlib/v/checker/tests/non_matching_functional_args.out
index 2247b78129..a89de0059b 100644
--- a/vlib/v/checker/tests/non_matching_functional_args.out
+++ b/vlib/v/checker/tests/non_matching_functional_args.out
@@ -1,4 +1,4 @@
-vlib/v/checker/tests/non_matching_functional_args.vv:27:6: error: invalid argument 1 to `sum`: expected `fn (Table)`, not `fn (mut Table)`
+vlib/v/checker/tests/non_matching_functional_args.vv:27:6: error: cannot use `fn (mut Table)` as `fn (Table)` in argument 1 to `sum`
    25 |
    26 | fn main() {
    27 |     sum(fn (mut t Table) {
@@ -6,7 +6,7 @@ vlib/v/checker/tests/non_matching_functional_args.vv:27:6: error: invalid argume
    28 |         t.rename()
    29 |         println(t.name)
 details: `main.MyFn`'s expected fn argument: `zzzz` is NOT a pointer, but the passed fn argument: `t` is a pointer
-vlib/v/checker/tests/non_matching_functional_args.vv:31:6: error: invalid argument 1 to `sum`: expected `fn (Table)`, not `fn (mut Table)`
+vlib/v/checker/tests/non_matching_functional_args.vv:31:6: error: cannot use `fn (mut Table)` as `fn (Table)` in argument 1 to `sum`
    29 |         println(t.name)
    30 |     })
    31 |     sum(xxx)
diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index 6b147ffa58..0abcf8cd2c 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -1138,6 +1138,9 @@ pub fn (mut f Fmt) expr(node ast.Expr) {
 			}
 			f.write('}')
 		}
+		ast.ArrayDecompose {
+			f.expr(node.expr)
+		}
 	}
 }
 
diff --git a/vlib/v/gen/auto_str_methods.v b/vlib/v/gen/auto_str_methods.v
index d7cf3f76c0..cec340dd22 100644
--- a/vlib/v/gen/auto_str_methods.v
+++ b/vlib/v/gen/auto_str_methods.v
@@ -63,15 +63,6 @@ fn (mut g Gen) gen_str_for_type(typ table.Type) string {
 			}
 		}
 	}
-	// if varg, generate str for varg
-	if typ.has_flag(.variadic) {
-		varg_already_generated_key := 'varg_$already_generated_key'
-		if varg_already_generated_key !in g.str_types {
-			g.gen_str_for_varg(styp, str_fn_name, sym_has_str_method)
-			g.str_types << varg_already_generated_key
-		}
-		return 'varg_$str_fn_name'
-	}
 	if typ.has_flag(.optional) {
 		option_already_generated_key := 'option_$already_generated_key'
 		if option_already_generated_key !in g.str_types {
@@ -305,22 +296,6 @@ fn (mut g Gen) gen_str_for_map(info table.Map, styp string, str_fn_name string)
 	g.auto_str_funcs.writeln('}')
 }
 
-fn (mut g Gen) gen_str_for_varg(styp string, str_fn_name string, has_str_method bool) {
-	g.definitions.writeln('static string varg_${str_fn_name}(varg_$styp it); // auto')
-	g.auto_str_funcs.writeln('static string varg_${str_fn_name}(varg_$styp it) {')
-	g.auto_str_funcs.writeln('\tstrings__Builder sb = strings__new_builder(it.len);')
-	g.auto_str_funcs.writeln('\tstrings__Builder_write(&sb, _SLIT("["));')
-	g.auto_str_funcs.writeln('\tfor(int i=0; i<it.len; ++i) {')
-	g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${str_fn_name}(it.args[i]));')
-	g.auto_str_funcs.writeln('\t\tif (i < it.len-1) {')
-	g.auto_str_funcs.writeln('\t\t\tstrings__Builder_write(&sb, _SLIT(", "));')
-	g.auto_str_funcs.writeln('\t\t}')
-	g.auto_str_funcs.writeln('\t}')
-	g.auto_str_funcs.writeln('\tstrings__Builder_write(&sb, _SLIT("]"));')
-	g.auto_str_funcs.writeln('\treturn strings__Builder_str(&sb);')
-	g.auto_str_funcs.writeln('}')
-}
-
 fn (mut g Gen) gen_str_for_multi_return(info table.MultiReturn, styp string, str_fn_name string) {
 	for typ in info.types {
 		sym := g.table.get_type_symbol(typ)
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 1382188f8c..410571269d 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -56,7 +56,6 @@ mut:
 	last_fn_c_name                   string
 	tmp_count                        int // counter for unique tmp vars (_tmp1, tmp2 etc)
 	tmp_count2                       int // a separate tmp var counter for autofree fn calls
-	variadic_args                    map[string]int
 	is_c_call                        bool // e.g. `C.printf("v")`
 	is_assign_lhs                    bool // inside left part of assign expr (for array_set(), etc)
 	is_assign_rhs                    bool // inside right part of assign after `=` (val expr)
@@ -246,7 +245,6 @@ pub fn cgen(files []ast.File, table &table.Table, pref &pref.Preferences) string
 			g.definitions.writeln('int _v_type_idx_${typ.cname}() { return $idx; };')
 		}
 	}
-	g.write_variadic_types()
 	// g.write_str_definitions()
 	// v files are finished, what remains is pure C code
 	g.gen_vlines_reset()
@@ -704,21 +702,6 @@ pub fn (mut g Gen) write_multi_return_types() {
 	g.type_definitions.writeln('// END_multi_return_structs\n')
 }
 
-pub fn (mut g Gen) write_variadic_types() {
-	g.type_definitions.writeln('\n//BEGIN_variadic_structs')
-	for type_str, arg_len in g.variadic_args {
-		typ := table.Type(type_str.int())
-		type_name := g.typ(typ)
-		struct_name := 'varg_' + type_name.replace('*', '_ptr')
-		g.type_definitions.writeln('struct $struct_name {')
-		g.type_definitions.writeln('\tint len;')
-		g.type_definitions.writeln('\t$type_name args[$arg_len];')
-		g.type_definitions.writeln('};\n')
-		g.typedefs.writeln('typedef struct $struct_name $struct_name;')
-	}
-	g.type_definitions.writeln('// END_variadic_structs\n')
-}
-
 pub fn (mut g Gen) write(s string) {
 	$if trace_gen ? {
 		eprintln('gen file: ${g.file.path:-30} | last_fn_c_name: ${g.last_fn_c_name:-45} | write: $s')
@@ -1324,16 +1307,6 @@ fn (mut g Gen) for_in(it ast.ForInStmt) {
 			g.writeln('\t${it.label}__break: {}')
 		}
 		return
-	} else if it.cond_type.has_flag(.variadic) {
-		g.writeln('// FOR IN cond_type/variadic')
-		i := if it.key_var in ['', '_'] { g.new_tmp_var() } else { it.key_var }
-		styp := g.typ(it.cond_type)
-		g.write('for (int $i = 0; $i < ')
-		g.expr(it.cond)
-		g.writeln('.len; ++$i) {')
-		g.write('\t$styp ${c_name(it.val_var)} = ')
-		g.expr(it.cond)
-		g.writeln('.args[$i];')
 	} else if it.kind == .string {
 		i := if it.key_var in ['', '_'] { g.new_tmp_var() } else { it.key_var }
 		g.write('for (int $i = 0; $i < ')
@@ -2374,6 +2347,9 @@ fn (mut g Gen) expr(node ast.Expr) {
 			fsym := g.table.get_type_symbol(node.typ)
 			g.write(fsym.name)
 		}
+		ast.ArrayDecompose {
+			g.expr(node.expr)
+		}
 		ast.ArrayInit {
 			g.array_init(node)
 		}
@@ -2775,7 +2751,8 @@ fn (mut g Gen) typeof_expr(node ast.TypeOf) {
 		info := sym.info as table.FnType
 		g.write('_SLIT("${g.fn_decl_str(info)}")')
 	} else if node.expr_type.has_flag(.variadic) {
-		g.write('_SLIT("...${util.strip_main_name(sym.name)}")')
+		varg_elem_type_sym := g.table.get_type_symbol(g.table.value_type(node.expr_type))
+		g.write('_SLIT("...${util.strip_main_name(varg_elem_type_sym.name)}")')
 	} else {
 		g.write('_SLIT("${util.strip_main_name(sym.name)}")')
 	}
@@ -3835,13 +3812,7 @@ fn (mut g Gen) index_expr(node ast.IndexExpr) {
 		else {
 			sym := g.table.get_type_symbol(node.left_type)
 			left_is_ptr := node.left_type.is_ptr()
-			if node.left_type.has_flag(.variadic) {
-				g.expr(node.left)
-				g.write('.args')
-				g.write('[')
-				g.expr(node.index)
-				g.write(']')
-			} else if sym.kind == .array {
+			if sym.kind == .array {
 				info := sym.info as table.Array
 				elem_type_str := g.typ(info.elem_type)
 				elem_typ := g.table.get_type_symbol(info.elem_type)
diff --git a/vlib/v/gen/cheaders.v b/vlib/v/gen/cheaders.v
index df64fa1771..5ff4843cda 100644
--- a/vlib/v/gen/cheaders.v
+++ b/vlib/v/gen/cheaders.v
@@ -52,10 +52,8 @@ const (
 #endif
 
 #ifdef __TINYC__
-	#undef EMPTY_VARG_INITIALIZATION
 	#undef EMPTY_STRUCT_DECLARATION
 	#undef EMPTY_STRUCT_INITIALIZATION
-	#define EMPTY_VARG_INITIALIZATION
 	#define EMPTY_STRUCT_DECLARATION char _dummy
 	#define EMPTY_STRUCT_INITIALIZATION 0
 	#undef EMPTY_ARRAY_OF_ELEMS
diff --git a/vlib/v/gen/fn.v b/vlib/v/gen/fn.v
index bf9c139552..216d6e2391 100644
--- a/vlib/v/gen/fn.v
+++ b/vlib/v/gen/fn.v
@@ -215,14 +215,6 @@ fn (mut g Gen) fn_args(args []table.Param, is_variadic bool) ([]string, []string
 		typ := g.unwrap_generic(arg.typ)
 		arg_type_sym := g.table.get_type_symbol(typ)
 		mut arg_type_name := g.typ(typ) // util.no_dots(arg_type_sym.name)
-		is_varg := i == args.len - 1 && is_variadic
-		if is_varg {
-			varg_type_str := int(arg.typ).str()
-			if varg_type_str !in g.variadic_args {
-				g.variadic_args[varg_type_str] = 0
-			}
-			arg_type_name = 'varg_' + g.typ(arg.typ).replace('*', '_ptr')
-		}
 		if arg_type_sym.kind == .function {
 			info := arg_type_sym.info as table.FnType
 			func := info.func
@@ -764,10 +756,8 @@ fn (mut g Gen) call_args(node ast.CallExpr) {
 	args := if g.is_js_call { node.args[1..] } else { node.args }
 	expected_types := node.expected_arg_types
 	is_variadic := expected_types.len > 0 && expected_types[expected_types.len - 1].has_flag(.variadic)
-	is_forwarding_varg := args.len > 0 && args[args.len - 1].typ.has_flag(.variadic)
-	gen_vargs := is_variadic && !is_forwarding_varg
 	for i, arg in args {
-		if gen_vargs && i == expected_types.len - 1 {
+		if is_variadic && i == expected_types.len - 1 {
 			break
 		}
 		use_tmp_var_autofree := g.autofree && arg.typ == table.string_type && arg.is_tmp_autofree &&
@@ -818,32 +808,33 @@ fn (mut g Gen) call_args(node ast.CallExpr) {
 		if is_interface {
 			g.write(')')
 		}
-		if i < args.len - 1 || gen_vargs {
+		if i < args.len - 1 || is_variadic {
 			g.write(', ')
 		}
 	}
 	arg_nr := expected_types.len - 1
-	if gen_vargs {
+	if is_variadic {
 		varg_type := expected_types[expected_types.len - 1]
-		struct_name := 'varg_' + g.typ(varg_type).replace('*', '_ptr')
 		variadic_count := args.len - arg_nr
-		varg_type_str := int(varg_type).str()
-		if variadic_count > g.variadic_args[varg_type_str] {
-			g.variadic_args[varg_type_str] = variadic_count
-		}
-		g.write('($struct_name){.len=$variadic_count,.args={')
-		if variadic_count > 0 {
-			for j in arg_nr .. args.len {
-				g.ref_or_deref_arg(args[j], varg_type)
-				if j < args.len - 1 {
-					g.write(', ')
-				}
-			}
+		arr_sym := g.table.get_type_symbol(varg_type)
+		arr_info := arr_sym.info as table.Array
+		elem_type := g.typ(arr_info.elem_type)
+		if args.len > 0 && args[args.len - 1].expr is ast.ArrayDecompose {
+			g.expr(args[args.len - 1].expr)
 		} else {
-			// NB: tcc can not handle 0 here, while msvc needs it
-			g.write('EMPTY_VARG_INITIALIZATION')
+			if variadic_count > 0 {
+				g.write('new_array_from_c_array($variadic_count, $variadic_count, sizeof($elem_type), _MOV(($elem_type[$variadic_count]){')
+				for j in arg_nr .. args.len {
+					g.ref_or_deref_arg(args[j], arr_info.elem_type)
+					if j < args.len - 1 {
+						g.write(', ')
+					}
+				}
+				g.write('}))')
+			} else {
+				g.write('__new_array_with_default(0, 0, sizeof($elem_type), 0)')
+			}
 		}
-		g.write('}}')
 	}
 }
 
diff --git a/vlib/v/gen/js/js.v b/vlib/v/gen/js/js.v
index 7b8fcf23d6..924eb147d2 100644
--- a/vlib/v/gen/js/js.v
+++ b/vlib/v/gen/js/js.v
@@ -16,7 +16,8 @@ const (
 		'public', 'return', 'static', 'super', 'switch', 'this', 'throw', 'try', 'typeof', 'var', 'void',
 		'while', 'with', 'yield', 'Number', 'String', 'Boolean', 'Array', 'Map']
 	// used to generate type structs
-	v_types = ['i8', 'i16', 'int', 'i64', 'byte', 'u16', 'u32', 'u64', 'f32', 'f64', 'any_int', 'any_float', 'size_t', 'bool', 'string', 'map', 'array']
+	v_types     = ['i8', 'i16', 'int', 'i64', 'byte', 'u16', 'u32', 'u64', 'f32', 'f64', 'any_int',
+		'any_float', 'size_t', 'bool', 'string', 'map', 'array']
 	tabs        = ['', '\t', '\t\t', '\t\t\t', '\t\t\t\t', '\t\t\t\t\t', '\t\t\t\t\t\t', '\t\t\t\t\t\t\t',
 		'\t\t\t\t\t\t\t\t', '\t\t\t\t\t\t\t\t\t', '\t\t\t\t\t\t\t\t\t', '\t\t\t\t\t\t\t\t\t']
 )
@@ -32,30 +33,30 @@ mut:
 }
 
 struct JsGen {
-	table             &table.Table
-	pref              &pref.Preferences
+	table               &table.Table
+	pref                &pref.Preferences
 mut:
-	definitions       	strings.Builder
-	ns                	&Namespace
-	namespaces        	map[string]&Namespace
-	doc               	&JsDoc
-	enable_doc        	bool
-	file              	ast.File
-	tmp_count         	int
-	inside_ternary    	bool
-	inside_loop       	bool
-	inside_map_set    	bool // map.set(key, value)
-	inside_builtin    	bool
-	generated_builtin 	bool
+	definitions         strings.Builder
+	ns                  &Namespace
+	namespaces          map[string]&Namespace
+	doc                 &JsDoc
+	enable_doc          bool
+	file                ast.File
+	tmp_count           int
+	inside_ternary      bool
+	inside_loop         bool
+	inside_map_set      bool // map.set(key, value)
+	inside_builtin      bool
+	generated_builtin   bool
 	inside_def_typ_decl bool
-	is_test           	bool
-	stmt_start_pos    	int
-	defer_stmts       	[]ast.DeferStmt
-	fn_decl           	&ast.FnDecl // pointer to the FnDecl we are currently inside otherwise 0
-	str_types         	[]string // types that need automatic str() generation
-	method_fn_decls   	map[string][]ast.FnDecl
-	builtin_fns       	[]string // Functions defined in `builtin`
-	empty_line        	bool
+	is_test             bool
+	stmt_start_pos      int
+	defer_stmts         []ast.DeferStmt
+	fn_decl             &ast.FnDecl // pointer to the FnDecl we are currently inside otherwise 0
+	str_types           []string // types that need automatic str() generation
+	method_fn_decls     map[string][]ast.FnDecl
+	builtin_fns         []string // Functions defined in `builtin`
+	empty_line          bool
 }
 
 pub fn gen(files []ast.File, table &table.Table, pref &pref.Preferences) string {
@@ -158,12 +159,16 @@ pub fn gen(files []ast.File, table &table.Table, pref &pref.Preferences) string
 			out += '// builtin type casts\n'
 			out += 'const ['
 			for i, typ in v_types {
-				if i > 0 { out += ', ' }
+				if i > 0 {
+					out += ', '
+				}
 				out += '$typ'
 			}
 			out += '] = ['
 			for i, typ in v_types {
-				if i > 0 { out += ',' }
+				if i > 0 {
+					out += ','
+				}
 				out += '\n\tfunction(val) { return new builtin.${typ}(val) }'
 			}
 			out += '\n]\n'
@@ -257,14 +262,18 @@ pub fn (mut g JsGen) dec_indent() {
 
 [inline]
 pub fn (mut g JsGen) write(s string) {
-	if g.ns == 0 { verror('g.write: not in a namespace') }
+	if g.ns == 0 {
+		verror('g.write: not in a namespace')
+	}
 	g.gen_indent()
 	g.ns.out.write(s)
 }
 
 [inline]
 pub fn (mut g JsGen) writeln(s string) {
-	if g.ns == 0 { verror('g.writeln: not in a namespace') }
+	if g.ns == 0 {
+		verror('g.writeln: not in a namespace')
+	}
 	g.gen_indent()
 	g.ns.out.writeln(s)
 	g.empty_line = true
@@ -304,7 +313,13 @@ fn (mut g JsGen) js_name(name_ string) string {
 		is_js = true
 	}
 	ns := get_ns(name)
-	name = if g.ns == 0 { name } else if ns == g.ns.name { name.split('.').last() } else { g.get_alias(name) }
+	name = if g.ns == 0 {
+		name
+	} else if ns == g.ns.name {
+		name.split('.').last()
+	} else {
+		g.get_alias(name)
+	}
 	mut parts := name.split('.')
 	if !is_js {
 		for i, p in parts {
@@ -529,8 +544,10 @@ fn (mut g JsGen) expr(node ast.Expr) {
 			g.gen_string_inter_literal(node)
 		}
 		ast.StringLiteral {
-			text := node.val.replace('\'', "\\'")
-			if g.file.mod.name == 'builtin' { g.write('new ') }
+			text := node.val.replace("\'", "\\'")
+			if g.file.mod.name == 'builtin' {
+				g.write('new ')
+			}
 			g.write("string('$text')")
 		}
 		ast.StructInit {
@@ -559,6 +576,7 @@ fn (mut g JsGen) expr(node ast.Expr) {
 		ast.UnsafeExpr {
 			g.expr(node.expr)
 		}
+		ast.ArrayDecompose {}
 	}
 }
 
@@ -1012,19 +1030,22 @@ fn (mut g JsGen) gen_struct_decl(node ast.StructDecl) {
 	if !('toString' in fn_names) {
 		g.writeln('toString() {')
 		g.inc_indent()
-		g.write('return `${js_name} {')
+		g.write('return `$js_name {')
 		for i, field in node.fields {
-			g.write(if i == 0 { ' ' } else { ', ' })
+			g.write(if i == 0 {
+				' '
+			} else {
+				', '
+			})
 			match g.typ(field.typ).split('.').last() {
-				"string" { g.write('$field.name: "\${this["${field.name}"].toString()}"') }
-				else { g.write('$field.name: \${this["${field.name}"].toString()} ') }
+				'string' { g.write('$field.name: "\${this["$field.name"].toString()}"') }
+				else { g.write('$field.name: \${this["$field.name"].toString()} ') }
 			}
 		}
 		g.writeln('}`')
 		g.dec_indent()
 		g.writeln('}')
 	}
-
 	g.dec_indent()
 	g.writeln('};\n')
 	if node.is_pub {
@@ -1378,31 +1399,49 @@ fn (mut g JsGen) gen_infix_expr(it ast.InfixExpr) {
 fn (mut g JsGen) greater_typ(left table.Type, right table.Type) table.Type {
 	l := int(left)
 	r := int(right)
-	lr := [l,r]
-
-	if table.string_type_idx in lr { return table.Type(table.string_type_idx) }
-
-	should_float := (l in table.integer_type_idxs && r in table.float_type_idxs) || (r in table.integer_type_idxs && l in table.float_type_idxs)
+	lr := [l, r]
+	if table.string_type_idx in lr {
+		return table.Type(table.string_type_idx)
+	}
+	should_float := (l in table.integer_type_idxs &&
+		r in table.float_type_idxs) ||
+		(r in table.integer_type_idxs && l in table.float_type_idxs)
 	if should_float {
-		if table.f64_type_idx in lr { return table.Type(table.f64_type_idx) }
-		if table.f32_type_idx in lr { return table.Type(table.f32_type_idx) }
+		if table.f64_type_idx in lr {
+			return table.Type(table.f64_type_idx)
+		}
+		if table.f32_type_idx in lr {
+			return table.Type(table.f32_type_idx)
+		}
 		return table.Type(table.any_flt_type)
 	}
-
 	should_int := (l in table.integer_type_idxs && r in table.integer_type_idxs)
 	if should_int {
 		// cant add to u64 - if (table.u64_type_idx in lr) { return table.Type(table.u64_type_idx) }
 		// just guessing this order
-		if table.i64_type_idx in lr { return table.Type(table.i64_type_idx) }
-		if table.u32_type_idx in lr { return table.Type(table.u32_type_idx) }
-		if table.int_type_idx in lr { return table.Type(table.int_type_idx) }
-		if table.u16_type_idx in lr { return table.Type(table.u16_type_idx) }
-		if table.i16_type_idx in lr { return table.Type(table.i16_type_idx) }
-		if table.byte_type_idx in lr { return table.Type(table.byte_type_idx) }
-		if table.i8_type_idx in lr { return table.Type(table.i8_type_idx) }
+		if table.i64_type_idx in lr {
+			return table.Type(table.i64_type_idx)
+		}
+		if table.u32_type_idx in lr {
+			return table.Type(table.u32_type_idx)
+		}
+		if table.int_type_idx in lr {
+			return table.Type(table.int_type_idx)
+		}
+		if table.u16_type_idx in lr {
+			return table.Type(table.u16_type_idx)
+		}
+		if table.i16_type_idx in lr {
+			return table.Type(table.i16_type_idx)
+		}
+		if table.byte_type_idx in lr {
+			return table.Type(table.byte_type_idx)
+		}
+		if table.i8_type_idx in lr {
+			return table.Type(table.i8_type_idx)
+		}
 		return table.Type(table.any_int_type_idx)
 	}
-
 	return table.Type(l)
 }
 
@@ -1439,7 +1478,9 @@ fn (mut g JsGen) gen_selector_expr(it ast.SelectorExpr) {
 }
 
 fn (mut g JsGen) gen_string_inter_literal(it ast.StringInterLiteral) {
-	if g.file.mod.name == 'builtin' { g.write('new ') }
+	if g.file.mod.name == 'builtin' {
+		g.write('new ')
+	}
 	g.write('string(`')
 	for i, val in it.vals {
 		escaped_val := val.replace('`', '\\`')
@@ -1517,10 +1558,9 @@ fn (mut g JsGen) gen_typeof_expr(it ast.TypeOf) {
 }
 
 fn (mut g JsGen) gen_type_cast_expr(it ast.CastExpr) {
-	is_literal := (
-		(it.expr is ast.IntegerLiteral && it.typ in table.integer_type_idxs) ||
-		(it.expr is ast.FloatLiteral && it.typ in table.float_type_idxs)
-	)
+	is_literal := ((it.expr is ast.IntegerLiteral &&
+		it.typ in table.integer_type_idxs) ||
+		(it.expr is ast.FloatLiteral && it.typ in table.float_type_idxs))
 	typ := g.typ(it.typ)
 	if !is_literal {
 		if !(typ in v_types) || g.ns.name == 'builtin' {
diff --git a/vlib/v/gen/str.v b/vlib/v/gen/str.v
index c0c3abc938..e39c971948 100644
--- a/vlib/v/gen/str.v
+++ b/vlib/v/gen/str.v
@@ -224,8 +224,6 @@ fn (mut g Gen) string_inter_literal(node ast.StringInterLiteral) {
 			} else {
 				g.write('*.*s')
 			}
-		} else if typ.has_flag(.variadic) {
-			g.write('.*s')
 		} else if typ.is_float() {
 			g.write('$fmt${fspec:c}')
 		} else if typ.is_pointer() {
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index 23f813bfdb..c18ec96fb6 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -126,6 +126,13 @@ pub fn (mut p Parser) call_args() []ast.CallArg {
 		mut comments := p.eat_comments()
 		arg_start_pos := p.tok.position()
 		mut e := p.expr(0)
+		if p.tok.kind == .ellipsis {
+			p.next()
+			e = ast.ArrayDecompose{
+				expr: e
+				pos: p.tok.position()
+			}
+		}
 		if mut e is ast.StructInit {
 			e.pre_comments << comments
 			comments = []ast.Comment{}
@@ -533,7 +540,7 @@ fn (mut p Parser) fn_args() ([]table.Param, bool, bool) {
 				}
 			}
 			if is_variadic {
-				arg_type = arg_type.set_flag(.variadic)
+				arg_type = table.new_type(p.table.find_or_register_array(arg_type, 1)).set_flag(.variadic)
 			}
 			if p.tok.kind == .eof {
 				p.error_with_pos('expecting `)`', p.prev_tok.position())
@@ -621,7 +628,7 @@ fn (mut p Parser) fn_args() ([]table.Param, bool, bool) {
 				}
 			}
 			if is_variadic {
-				typ = typ.set_flag(.variadic)
+				typ = table.new_type(p.table.find_or_register_array(typ, 1)).set_flag(.variadic)
 			}
 			for i, arg_name in arg_names {
 				args << table.Param{
diff --git a/vlib/v/table/table.v b/vlib/v/table/table.v
index e681ccd3eb..ebb06c5bf6 100644
--- a/vlib/v/table/table.v
+++ b/vlib/v/table/table.v
@@ -641,7 +641,9 @@ pub fn (t &Table) value_type(typ Type) Type {
 	typ_sym := t.get_type_symbol(typ)
 	if typ.has_flag(.variadic) {
 		// ...string => string
-		return typ.clear_flag(.variadic)
+		// return typ.clear_flag(.variadic)
+		array_info := typ_sym.info as Array
+		return array_info.elem_type
 	}
 	if typ_sym.kind == .array {
 		// Check index type
diff --git a/vlib/v/table/types.v b/vlib/v/table/types.v
index 74a8173c73..ae5675e1f4 100644
--- a/vlib/v/table/types.v
+++ b/vlib/v/table/types.v
@@ -718,9 +718,13 @@ pub fn (table &Table) type_to_str_using_aliases(t Type, import_aliases map[strin
 			if t == array_type {
 				return 'array'
 			}
-			info := sym.info as Array
-			elem_str := table.type_to_str_using_aliases(info.elem_type, import_aliases)
-			res = '[]$elem_str'
+			if t.has_flag(.variadic) {
+				res = table.type_to_str_using_aliases(table.value_type(t), import_aliases)
+			} else {
+				info := sym.info as Array
+				elem_str := table.type_to_str_using_aliases(info.elem_type, import_aliases)
+				res = '[]$elem_str'
+			}
 		}
 		.array_fixed {
 			info := sym.info as ArrayFixed
diff --git a/vlib/v/tests/fn_variadic_test.v b/vlib/v/tests/fn_variadic_test.v
index 58355a31aa..391284a070 100644
--- a/vlib/v/tests/fn_variadic_test.v
+++ b/vlib/v/tests/fn_variadic_test.v
@@ -34,10 +34,10 @@ fn test_fn_variadic_generic() {
 */
 // forwarding
 fn variadic_forward_a(a ...string) string {
-	return variadic_forward_b(a)
+	return variadic_fn_a(a...)
 }
 
-fn variadic_forward_b(a ...string) string {
+fn variadic_fn_a(a ...string) string {
 	a0 := a[0]
 	a1 := a[1]
 	a2 := a[2]
@@ -64,6 +64,11 @@ fn test_variadic_only_with_no_vargs() {
 	fn_variadic_only_with_no_vargs()
 }
 
+fn test_array_decomposition_to_vargs() {
+	a := ['a', 'b', 'c']
+	assert variadic_fn_a(a...) == 'abc'
+}
+
 struct VaTestStruct {
 }
 
diff --git a/vlib/x/openssl/openssl.v b/vlib/x/openssl/openssl.v
index 3fa63aae1c..fcd693593e 100644
--- a/vlib/x/openssl/openssl.v
+++ b/vlib/x/openssl/openssl.v
@@ -180,13 +180,13 @@ pub fn (mut s SSLConn) socket_read_into_ptr(buf_ptr byteptr, len int) ?int {
 	return res
 }
 
-pub fn (mut s SSLConn) read_into(mut buffer []Byte) ?int {
+pub fn (mut s SSLConn) read_into(mut buffer []byte) ?int {
 	res := s.socket_read_into_ptr(byteptr(buffer.data), buffer.len)?
 	return res
 }
 
 // write number of bytes to SSL connection
-pub fn (mut s SSLConn) write(bytes []Byte) ? {
+pub fn (mut s SSLConn) write(bytes []byte) ? {
 	unsafe {
 		mut ptr_base := byteptr(bytes.data)
 		mut total_sent := 0