From 04e00a46d47bcdd3cf96f4bc3759060c65697f97 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Mon, 13 Feb 2023 08:13:52 -0300
Subject: [PATCH] cgen, checker: allow array decompose on non-variadic func
 call (e.g call(...arr)) (#17284)

---
 vlib/v/checker/fn.v                           |  12 +-
 .../checker/tests/arraydecompose_arg2_err.out |   6 +
 .../checker/tests/arraydecompose_arg2_err.vv  |   8 +
 .../checker/tests/arraydecompose_arg_err.out  |   6 +
 .../v/checker/tests/arraydecompose_arg_err.vv |   8 +
 vlib/v/fmt/fmt.v                              |   6 +-
 vlib/v/gen/c/comptime.v                       |  34 ++++-
 vlib/v/gen/c/fn.v                             |  13 ++
 .../v/tests/arraydecompose_nonvariadic_test.v | 137 ++++++++++++++++++
 9 files changed, 220 insertions(+), 10 deletions(-)
 create mode 100644 vlib/v/checker/tests/arraydecompose_arg2_err.out
 create mode 100644 vlib/v/checker/tests/arraydecompose_arg2_err.vv
 create mode 100644 vlib/v/checker/tests/arraydecompose_arg_err.out
 create mode 100644 vlib/v/checker/tests/arraydecompose_arg_err.vv
 create mode 100644 vlib/v/tests/arraydecompose_nonvariadic_test.v

diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index 6b074e0df6..a05cc46fd1 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -965,11 +965,14 @@ fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool) ast.
 		c.error('too many arguments in call to `${func.name}` (non-js backend: ${c.pref.backend})',
 			node.pos)
 	}
+	mut has_decompose := false
 	for i, mut call_arg in node.args {
 		if func.params.len == 0 {
 			continue
 		}
-
+		if !func.is_variadic && has_decompose {
+			c.error('cannot have parameter after array decompose', node.pos)
+		}
 		param := if func.is_variadic && i >= func.params.len - 1 {
 			func.params.last()
 		} else {
@@ -980,6 +983,7 @@ fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool) ast.
 				c.error('too many arguments in call to `${func.name}`', node.pos)
 			}
 		}
+		has_decompose = call_arg.expr is ast.ArrayDecompose
 		if func.is_variadic && i >= func.params.len - 1 {
 			param_sym := c.table.sym(param.typ)
 			mut expected_type := param.typ
@@ -2048,6 +2052,12 @@ fn (mut c Checker) check_expected_arg_count(mut node ast.CallExpr, f &ast.Fn) !
 	}
 	if f.is_variadic {
 		min_required_params--
+	} else {
+		has_decompose := node.args.filter(it.expr is ast.ArrayDecompose).len > 0
+		if has_decompose {
+			// if call(...args) is present
+			min_required_params = nr_args
+		}
 	}
 	if min_required_params < 0 {
 		min_required_params = 0
diff --git a/vlib/v/checker/tests/arraydecompose_arg2_err.out b/vlib/v/checker/tests/arraydecompose_arg2_err.out
new file mode 100644
index 0000000000..33ba8eb3fe
--- /dev/null
+++ b/vlib/v/checker/tests/arraydecompose_arg2_err.out
@@ -0,0 +1,6 @@
+vlib/v/checker/tests/arraydecompose_arg2_err.vv:7:12: error: cannot use `f64` as `int` in argument 1 to `test_arr`
+    5 | fn main() {
+    6 |   var := []f64{}
+    7 |   test_arr(...var)
+      |            ~~~~~~
+    8 | }
diff --git a/vlib/v/checker/tests/arraydecompose_arg2_err.vv b/vlib/v/checker/tests/arraydecompose_arg2_err.vv
new file mode 100644
index 0000000000..b4555387fe
--- /dev/null
+++ b/vlib/v/checker/tests/arraydecompose_arg2_err.vv
@@ -0,0 +1,8 @@
+fn test_arr(i int) string {
+  return '${i}'
+}
+
+fn main() {
+  var := []f64{}
+  test_arr(...var)
+}
\ No newline at end of file
diff --git a/vlib/v/checker/tests/arraydecompose_arg_err.out b/vlib/v/checker/tests/arraydecompose_arg_err.out
new file mode 100644
index 0000000000..1d86616dd9
--- /dev/null
+++ b/vlib/v/checker/tests/arraydecompose_arg_err.out
@@ -0,0 +1,6 @@
+vlib/v/checker/tests/arraydecompose_arg_err.vv:7:2: error: cannot have parameter after array decompose
+    5 | fn test_main() {
+    6 |     var := [0.0]
+    7 |     test_arr(1, ...var, 'a')
+      |     ~~~~~~~~~~~~~~~~~~~~~~~~
+    8 | }
diff --git a/vlib/v/checker/tests/arraydecompose_arg_err.vv b/vlib/v/checker/tests/arraydecompose_arg_err.vv
new file mode 100644
index 0000000000..df4f7844c0
--- /dev/null
+++ b/vlib/v/checker/tests/arraydecompose_arg_err.vv
@@ -0,0 +1,8 @@
+fn test_arr(i int, f f64, s string) string {
+	return '${i} : ${f}'
+}
+
+fn test_main() {
+	var := [0.0]
+	test_arr(1, ...var, 'a')
+}
diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index ee6ec22a28..9b7c9b1970 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -1906,7 +1906,11 @@ pub fn (mut f Fmt) comptime_call(node ast.ComptimeCall) {
 			inner_args := if node.args_var != '' {
 				node.args_var
 			} else {
-				node.args.map(it.str()).join(', ')
+				node.args.map(if it.expr is ast.ArrayDecompose {
+					'...${it.expr.expr.str()}'
+				} else {
+					it.str()
+				}).join(', ')
 			}
 			method_expr := if node.has_parens {
 				'(${node.method_name}(${inner_args}))'
diff --git a/vlib/v/gen/c/comptime.v b/vlib/v/gen/c/comptime.v
index 371a419bd0..57ad0402f0 100644
--- a/vlib/v/gen/c/comptime.v
+++ b/vlib/v/gen/c/comptime.v
@@ -141,20 +141,24 @@ fn (mut g Gen) comptime_call(mut node ast.ComptimeCall) {
 		} else {
 			false
 		}
+		mut has_decompose := !m.is_variadic
+			&& node.args.filter(it.expr is ast.ArrayDecompose).len > 0
 		// check argument length and types
 		if m.params.len - 1 != node.args.len && !expand_strs {
 			if g.inside_call {
 				g.error('expected ${m.params.len - 1} arguments to method ${sym.name}.${m.name}, but got ${node.args.len}',
 					node.pos)
 			} else {
-				// do not generate anything if the argument lengths don't match
-				g.writeln('/* skipping ${sym.name}.${m.name} due to mismatched arguments list */')
-				// g.writeln('println(_SLIT("skipping ${node.sym.name}.$m.name due to mismatched arguments list"));')
-				// eprintln('info: skipping ${node.sym.name}.$m.name due to mismatched arguments list\n' +
-				//'method.params: $m.params, args: $node.args\n\n')
-				// verror('expected ${m.params.len-1} arguments to method ${node.sym.name}.$m.name, but got $node.args.len')
+				if !has_decompose {
+					// do not generate anything if the argument lengths don't match
+					g.writeln('/* skipping ${sym.name}.${m.name} due to mismatched arguments list */')
+					// g.writeln('println(_SLIT("skipping ${node.sym.name}.$m.name due to mismatched arguments list"));')
+					// eprintln('info: skipping ${node.sym.name}.$m.name due to mismatched arguments list\n' +
+					//'method.params: $m.params, args: $node.args\n\n')
+					// verror('expected ${m.params.len-1} arguments to method ${node.sym.name}.$m.name, but got $node.args.len')
+					return
+				}
 			}
-			return
 		}
 
 		if !g.inside_call && (m.return_type.has_flag(.option) || m.return_type.has_flag(.result)) {
@@ -181,7 +185,21 @@ fn (mut g Gen) comptime_call(mut node ast.ComptimeCall) {
 					continue
 				}
 			}
-			if i - 1 < node.args.len - 1 {
+			if (i - 1 <= node.args.len - 1) && has_decompose
+				&& node.args[i - 1].expr is ast.ArrayDecompose {
+				mut d_count := 0
+				for d_i in i .. m.params.len {
+					g.write('*(${g.typ(m.params[i].typ)}*)array_get(')
+					g.expr(node.args[i - 1].expr)
+					g.write(', ${d_count})')
+
+					if d_i < m.params.len - 1 {
+						g.write(', ')
+					}
+					d_count++
+				}
+				break
+			} else if i - 1 < node.args.len - 1 {
 				g.expr(node.args[i - 1].expr)
 				g.write(', ')
 			} else if !expand_strs && i == node.args.len {
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 9d1b23532a..104b0e1d7f 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -1759,6 +1759,19 @@ fn (mut g Gen) call_args(node ast.CallExpr) {
 					}
 				}
 			}
+		} else if arg.expr is ast.ArrayDecompose {
+			mut d_count := 0
+			for d_i in i .. expected_types.len {
+				g.write('*(${g.typ(expected_types[d_i])}*)array_get(')
+				g.expr(arg.expr)
+				g.write(', ${d_count})')
+
+				if d_i < expected_types.len - 1 {
+					g.write(', ')
+				}
+				d_count++
+			}
+			continue
 		}
 		use_tmp_var_autofree := g.is_autofree && arg.typ == ast.string_type && arg.is_tmp_autofree
 			&& !g.inside_const && !g.is_builtin_mod
diff --git a/vlib/v/tests/arraydecompose_nonvariadic_test.v b/vlib/v/tests/arraydecompose_nonvariadic_test.v
new file mode 100644
index 0000000000..08b3b2a7a7
--- /dev/null
+++ b/vlib/v/tests/arraydecompose_nonvariadic_test.v
@@ -0,0 +1,137 @@
+type Any = f64 | int | string
+
+struct Test {}
+
+struct Test2 {}
+
+struct Test3 {}
+
+fn (t Test) test(args ...Any) {
+	println('called with ${args}')
+}
+
+fn (t Test2) test_str(arg string) {
+	println('called with ${arg}')
+}
+
+fn (t Test2) test_int(arg int, arg2 int) {
+	println('called with ${arg}, ${arg2}')
+}
+
+fn (t Test3) test_int(arg int, arg2 int) {
+	println('called with ${arg}, ${arg2}')
+}
+
+fn foo_any(i Any, k Any, j Any) string {
+	return '${i} : ${k} : ${j}'
+}
+
+fn foo(i int, k int) string {
+	return '${i} : ${k}'
+}
+
+fn bar(i f64, k f64, j f64) string {
+	return '${i} : ${k} : ${j}'
+}
+
+fn baz(s string) string {
+	return s
+}
+
+fn f_arr(i int, f f64) string {
+	return '${i} : ${f}'
+}
+
+fn f_var(s string, args ...string) string {
+	return '${s} [ ${args.map(it).join(',')} ]'
+}
+
+fn varargs[T](args ...T) string {
+	assert args.len > 0
+	return args.map(it.str()).join(' : ')
+}
+
+fn call[T](func_name string, args ...T) string {
+	return match func_name {
+		'foo' { foo(...args) }
+		'bar' { bar(...args) }
+		'baz' { baz(...args) }
+		'varargs' { varargs(...args) }
+		else { '' }
+	}
+}
+
+fn call_any(func_name string, args ...Any) string {
+	return match func_name {
+		'foo_any' { foo_any(...args) }
+		else { '' }
+	}
+}
+
+fn comptime_call[T](instance T, method_name string, args ...Any) bool {
+	$for method in T.methods {
+		if method.name == method_name {
+			instance.$method(...args)
+			return true
+		}
+	}
+	return false
+}
+
+fn comptime_call_vargs[T, R](instance T, method_name string, args ...R) bool {
+	$for method in T.methods {
+		if method.name == method_name {
+			instance.$method(...args)
+			return true
+		}
+	}
+	return false
+}
+
+fn comptime_call_vargs2[T, R](instance T, method_name string, args ...R) bool {
+	$for method in T.methods {
+		if method.name == method_name {
+			instance.$method(200, ...args)
+			return true
+		}
+	}
+	return false
+}
+
+fn test_main() {
+	assert call('foo', 10, 100) == '10 : 100'
+	assert call('bar', 1.1, 1.2, 1.3) == '1.1 : 1.2 : 1.3'
+	assert call('baz', 'test') == 'test'
+	assert call_any('foo_any', 10, 1.2, 'test') == "Any(10) : Any(1.2) : Any('test')"
+	assert call[Any]('varargs', 10, 1.2, 'test') == "Any(10) : Any(1.2) : Any('test')"
+
+	a := []int{len: 2, init: 50}
+	assert foo(...a) == '50 : 50'
+
+	b := []f64{len: 3, init: 1.2}
+	assert bar(...b) == '1.2 : 1.2 : 1.2'
+
+	mut c := []Any{}
+	c << 10
+	c << 1.2
+	c << 'test'
+	assert varargs(...c) == "Any(10) : Any(1.2) : Any('test')"
+
+	var := [0.0]
+	assert f_arr(1, ...var) == '1 : 0.0'
+
+	var2 := ['a', 'b', 'c']
+	assert f_var('foo', ...var2) == 'foo [ a,b,c ]'
+}
+
+fn test_comptime() {
+	var := Test{}
+	assert comptime_call(var, 'test', 1, 2.3, '')
+
+	var2 := Test2{}
+	assert comptime_call_vargs(var2, 'test_int', 1, 100)
+	assert comptime_call_vargs(var2, 'test_str', 'foo')
+
+	var3 := Test3{}
+	assert comptime_call_vargs2(var3, 'test_int', 100)
+}