From 0d7cc8829a00315f4cec087bd83df956371a188c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kr=C3=BCger?=
 <45282134+UweKrueger@users.noreply.github.com>
Date: Mon, 17 Aug 2020 23:35:36 +0200
Subject: [PATCH] cgen: implement channel `push()`/`pop()` using `<-` operator
 (#6154)

---
 vlib/sync/channel_select_2_test.v | 22 ++++++++--------
 vlib/v/ast/ast.v                  |  8 +++---
 vlib/v/checker/checker.v          |  1 +
 vlib/v/gen/cgen.v                 | 42 ++++++++++++++++++++++++++-----
 4 files changed, 52 insertions(+), 21 deletions(-)

diff --git a/vlib/sync/channel_select_2_test.v b/vlib/sync/channel_select_2_test.v
index abea5f081f..1a4f3a216a 100644
--- a/vlib/sync/channel_select_2_test.v
+++ b/vlib/sync/channel_select_2_test.v
@@ -1,45 +1,42 @@
 import sync
+import time
 
 fn do_rec_i64(ch chan i64) {
 	mut sum := i64(0)
 	for _ in 0 .. 300 {
-		mut a := i64(0)
-		(&sync.Channel(ch)).pop(&a)
-		sum += a
+		sum += <-ch
 	}
 	assert sum == 300 * (300 - 1) / 2
 }
 
 fn do_send_int(ch chan int) {
 	for i in 0 .. 300 {
-		(&sync.Channel(ch)).push(&i)
+		ch <- i
 	}
 }
 
 fn do_send_byte(ch chan byte) {
 	for i in 0 .. 300 {
-		ii := byte(i)
-		(&sync.Channel(ch)).push(&ii)
+		ch <- byte(i)
 	}
 }
 
-fn do_send_i64(mut ch sync.Channel) {
+fn do_send_i64(ch chan i64) {
 	for i in 0 .. 300 {
-		ii := i64(i)
-		ch.push(&ii)
+		ch <- i
 	}
 }
 
 fn test_select() {
 	chi := chan int{}
-	mut chl := sync.new_channel<i64>(1)
+	chl := chan i64{cap: 1}
 	chb := chan byte{cap: 10}
 	recch := chan i64{cap: 0}
 	go do_rec_i64(recch)
 	go do_send_int(chi)
 	go do_send_byte(chb)
-	go do_send_i64(mut chl)
-	mut channels := [&sync.Channel(chi), &sync.Channel(recch), chl, &sync.Channel(chb)]
+	go do_send_i64(chl)
+	mut channels := [&sync.Channel(chi), &sync.Channel(recch), &sync.Channel(chl), &sync.Channel(chb)]
 	directions := [sync.Direction.pop, .push, .pop, .pop]
 	mut sum := i64(0)
 	mut rl := i64(0)
@@ -73,4 +70,5 @@ fn test_select() {
 		256 * (256 - 1) / 2 +
 		44 * (44 - 1) / 2
 	assert sum == expected_sum
+	time.sleep_ms(20) // to give assert in coroutine enough time
 }
diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index 4d4789db3a..5347478aa1 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -435,9 +435,11 @@ pub mut:
 
 pub struct PrefixExpr {
 pub:
-	op    token.Kind
-	right Expr
-	pos   token.Position
+	op         token.Kind
+	right      Expr
+	pos        token.Position
+pub mut:
+	right_type table.Type
 }
 
 pub struct IndexExpr {
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index fbf23c45ab..6469f42945 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -2439,6 +2439,7 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 		}
 		ast.PrefixExpr {
 			right_type := c.expr(node.right)
+			node.right_type = right_type
 			// TODO: testing ref/deref strategy
 			if node.op == .amp && !right_type.is_ptr() {
 				return right_type.to_ptr()
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 26921c3b43..9bf1775987 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -498,8 +498,21 @@ typedef struct {
 				g.type_definitions.writeln('typedef _Interface ${c_name(typ.name)};')
 			}
 			.chan {
-				styp := util.no_dots(typ.name)
-				g.type_definitions.writeln('typedef chan $styp;')
+				if typ.name != 'chan' {
+					styp := util.no_dots(typ.name)
+					g.type_definitions.writeln('typedef chan $styp;')
+					el_stype := g.typ(typ.chan_info().elem_type)
+					g.hotcode_definitions.writeln('
+static inline $el_stype __${styp}_popval($styp ch) {
+	$el_stype val;
+	sync__Channel_try_pop_priv(ch, &val, false);
+	return val;
+}')
+					g.hotcode_definitions.writeln('
+static inline void __${styp}_pushval($styp ch, $el_stype val) {
+	sync__Channel_try_push_priv(ch, &val, false);
+}')
+				}
 			}
 			.map {
 				styp := util.no_dots(typ.name)
@@ -1969,11 +1982,20 @@ fn (mut g Gen) expr(node ast.Expr) {
 			if node.op == .amp {
 				g.is_amp = true
 			}
-			// g.write('/*pref*/')
-			g.write(node.op.str())
-			// g.write('(')
+			if node.op == .arrow {
+				right_type := g.unwrap_generic(node.right_type)
+				right_sym := g.table.get_type_symbol(right_type)
+				styp := util.no_dots(right_sym.name)
+				g.write('__${styp}_popval(')
+			} else {
+				// g.write('/*pref*/')
+				g.write(node.op.str())
+				// g.write('(')
+			}
 			g.expr(node.right)
-			// g.write(')')
+			if node.op == .arrow {
+				g.write(')')
+			}
 			g.is_amp = false
 		}
 		ast.RangeExpr {
@@ -2326,6 +2348,14 @@ fn (mut g Gen) infix_expr(node ast.InfixExpr) {
 			}
 			g.write(' }))')
 		}
+	} else if node.op == .arrow {
+		// chan <- val
+		styp := util.no_dots(left_sym.name)
+		g.write('__${styp}_pushval(')
+		g.expr(node.left)
+		g.write(', ')
+		g.expr(node.right)
+		g.write(')')
 	} else if unaliased_left.idx() in [table.u32_type_idx, table.u64_type_idx] && unaliased_right.is_signed() &&
 		node.op in [.eq, .ne, .gt, .lt, .ge, .le] {
 		bitsize := if unaliased_left.idx() == table.u32_type_idx &&