parser: don't require unary `>` prefix for `select` timeout (#10928)

cmd/tools/vwatch.v

@@ -270,7 +270,7 @@ fn (mut context Context) compilation_runner_loop() {
 							return
 						}
 					}
-					> 100 * time.millisecond {
+					100 * time.millisecond {
 						should_restart := RerunCommand.restart in cmds
 						cmds = []
 						if should_restart {

doc/docs.md

@@ -3350,7 +3350,7 @@ fn main() {
 			time.sleep(5 * time.millisecond)
 			eprintln('> c: $c was send on channel ch3')
 		}
-		> 500 * time.millisecond {
+		500 * time.millisecond {
 			// do something if no channel has become ready within 0.5s
 			eprintln('> more than 0.5s passed without a channel being ready')
 		}

vlib/context/README.md

@@ -99,7 +99,7 @@ fn example_with_deadline() {
 	ctx_ch := ctx.done()
 	select {
 		_ := <-ctx_ch {}
-		> 1 * time.second {
+		1 * time.second {
 			panic('This should not happen')
 		}
 	}
@@ -130,7 +130,7 @@ fn example_with_timeout() {
 	ctx_ch := ctx.done()
 	select {
 		_ := <-ctx_ch {}
-		> 1 * time.second {
+		1 * time.second {
 			panic('This should not happen')
 		}
 	}

vlib/context/deadline_test.v

@@ -22,7 +22,7 @@ fn test_with_deadline() {
 	ctx_ch := ctx.done()
 	select {
 		_ := <-ctx_ch {}
-		> 1 * time.second {
+		1 * time.second {
 			panic('This should not happen')
 		}
 	}
@@ -41,7 +41,7 @@ fn test_with_timeout() {
 	ctx_ch := ctx.done()
 	select {
 		_ := <-ctx_ch {}
-		> 1 * time.second {
+		1 * time.second {
 			panic('This should not happen')
 		}
 	}

vlib/sync/channel_select_3_test.v

@@ -32,7 +32,7 @@ fn f1(ch1 chan int, ch2 chan St, ch3 chan int, ch4 chan int, ch5 chan int, mut s
 		ch5 <- getint() {
 			a = 9
 		}
-		> 300 * time.millisecond {
+		300 * time.millisecond {
 			a = 3
 		}
 	}

vlib/v/checker/checker.v

@@ -6330,7 +6330,7 @@ pub fn (mut c Checker) select_expr(mut node ast.SelectExpr) ast.Type {
 				if branch.is_timeout {
 					if !branch.stmt.typ.is_int() {
 						tsym := c.table.get_type_symbol(branch.stmt.typ)
-						c.error('invalid type `$tsym.name` for timeout - expected integer type aka `time.Duration`',
+						c.error('invalid type `$tsym.name` for timeout - expected integer number of nanoseconds aka `time.Duration`',
 							branch.stmt.pos)
 					}
 				} else {

vlib/v/fmt/fmt.v

@@ -2169,9 +2169,6 @@ pub fn (mut f Fmt) select_expr(node ast.SelectExpr) {
 		if branch.is_else {
 			f.write('else {')
 		} else {
-			if branch.is_timeout {
-				f.write('> ')
-			}
 			f.single_line_if = true
 			match branch.stmt {
 				ast.ExprStmt { f.expr(branch.stmt.expr) }

vlib/v/fmt/tests/select_keep.vv

@@ -34,7 +34,7 @@ fn f1(ch1 chan int, ch2 chan St, ch3 chan int, ch4 chan int, ch5 chan int, sem s
 		ch5 <- getint() {
 			a = 9
 		}
-		> 300 * time.millisecond {
+		300 * time.millisecond {
 			a = 3
 		}
 		// post comment

vlib/v/parser/if_match.v

@@ -309,30 +309,14 @@ fn (mut p Parser) select_expr() ast.SelectExpr {
 			is_else = true
 			has_else = true
 			p.next()
-		} else if p.tok.kind == .gt {
-			if has_else {
-				p.error_with_pos('`else` and timeout `> t` are mutually exclusive `select` keys',
-					p.tok.position())
-				return ast.SelectExpr{}
-			}
-			if has_timeout {
-				p.error_with_pos('at most one timeout `> t` branch allowed in `select` block',
-					p.tok.position())
-				return ast.SelectExpr{}
-			}
-			is_timeout = true
-			has_timeout = true
-			p.next()
-			p.inside_match = true
-			expr := p.expr(0)
-			p.inside_match = false
-			stmt = ast.ExprStmt{
-				expr: expr
-				pos: expr.position()
-				comments: [comment]
-				is_expr: true
-			}
 		} else {
+			mut is_gt := false
+			if p.tok.kind == .gt {
+				is_gt = true
+				p.note_with_pos('`>` is deprecated and will soon be forbidden - just state the timeout in nanoseconds',
+					p.tok.position())
+				p.next()
+			}
 			p.inside_match = true
 			p.inside_select = true
 			exprs, comments := p.expr_list()
@@ -354,6 +338,7 @@ fn (mut p Parser) select_expr() ast.SelectExpr {
 			p.inside_select = false
 			match mut stmt {
 				ast.ExprStmt {
+					mut check_timeout := false
 					if !stmt.is_expr {
 						p.error_with_pos('select: invalid expression', stmt.pos)
 						return ast.SelectExpr{}
@@ -361,17 +346,30 @@ fn (mut p Parser) select_expr() ast.SelectExpr {
 						match mut stmt.expr {
 							ast.InfixExpr {
 								if stmt.expr.op != .arrow {
-									p.error_with_pos('select key: `<-` operator expected',
+									check_timeout = true
-										stmt.expr.pos)
+								} else if is_gt {
-									return ast.SelectExpr{}
+									p.error_with_pos('send expression cannot be used as timeout',
+										stmt.pos)
 								}
 							}
 							else {
-								p.error_with_pos('select key: send expression (`ch <- x`) expected',
+								check_timeout = true
+							}
+						}
+					}
+					if check_timeout {
+						if has_else {
+							p.error_with_pos('`else` and timeout value are mutually exclusive `select` keys',
 								stmt.pos)
 							return ast.SelectExpr{}
 						}
+						if has_timeout {
+							p.error_with_pos('at most one timeout branch allowed in `select` block',
+								stmt.pos)
+							return ast.SelectExpr{}
 						}
+						is_timeout = true
+						has_timeout = true
 					}
 				}
 				ast.AssignStmt {
@@ -392,7 +390,8 @@ fn (mut p Parser) select_expr() ast.SelectExpr {
 					}
 				}
 				else {
-					p.error_with_pos('select: transmission statement expected', stmt.pos)
+					p.error_with_pos('select: transmission statement, timeout (in ns) or `else` expected',
+						stmt.pos)
 					return ast.SelectExpr{}
 				}
 			}

vlib/v/parser/tests/select_bad_key_1.out

@@ -1,3 +1,10 @@
+vlib/v/parser/tests/select_bad_key_1.vv:19:3: notice: `>` is deprecated and will soon be forbidden - just state the timeout in nanoseconds
+   17 |             a++
+   18 |         }
+   19 |         > 50 * time.millisecond {
+      |         ^
+   20 |             println('timeout')
+   21 |         }
 vlib/v/parser/tests/select_bad_key_1.vv:39:8: error: select key: receive expression expected
    37 | fn f3_bad(ch1 chan St) {
    38 |     select {

vlib/v/parser/tests/select_bad_key_2.out

@@ -1,7 +1,7 @@
-vlib/v/parser/tests/select_bad_key_2.vv:7:5: error: select key: `<-` operator expected
+vlib/v/parser/tests/select_bad_key_2.vv:7:3: error: invalid type `f64` for timeout - expected integer number of nanoseconds aka `time.Duration`
     5 |             println(b)
     6 |         }
     7 |         a + 7 {
-      |           ^
+      |         ~~~~~
     8 |             println("shouldn't get here")
     9 |         }

vlib/v/parser/tests/select_bad_key_2.vv

@@ -1,5 +1,5 @@
 fn f3_bad(ch1 chan int) {
-	a := 5
+	a := 3.75
 	select {
 		b := <-ch1 {
 			println(b)

vlib/v/parser/tests/select_bad_key_3.out

@@ -1,7 +1,7 @@
-vlib/v/parser/tests/select_bad_key_3.vv:7:3: error: select key: send expression (`ch <- x`) expected
+vlib/v/parser/tests/select_bad_key_3.vv:6:3: error: invalid type `void` for timeout - expected integer number of nanoseconds aka `time.Duration`
-    5 |             println(b)
+    4 |             println(b)
-    6 |         }
+    5 |         }
-    7 |         println(7) {
+    6 |         println(7) {
       |         ~~~~~~~~~~
-    8 |             println("shouldn't get here")
+    7 |             println("shouldn't get here")
-    9 |         }
+    8 |         }

vlib/v/parser/tests/select_bad_key_3.vv

@@ -1,5 +1,4 @@
 fn f3_bad(ch1 chan int) {
-	a := 5
 	select {
 		b := <-ch1 {
 			println(b)

vlib/v/parser/tests/select_else_1.out

@@ -1,7 +1,7 @@
-vlib/v/parser/tests/select_else_1.vv:12:3: error: `else` and timeout `> t` are mutually exclusive `select` keys
+vlib/v/parser/tests/select_else_1.vv:12:3: error: `else` and timeout value are mutually exclusive `select` keys
    10 |             println("shouldn't get here")
    11 |         }
-   12 |         > 30 * time.millisecond {
+   12 |         30 * time.millisecond {
-      |         ^
+      |         ~~~~~~~~~~~~~~~~~~~~~
    13 |             println('bad')
    14 |         }

vlib/v/parser/tests/select_else_1.vv

@@ -9,7 +9,7 @@ fn f3_bad(ch1 chan int) {
 		else {
 			println("shouldn't get here")
 		}
-		> 30 * time.millisecond {
+		30 * time.millisecond {
 			println('bad')
 		}
 	}

vlib/v/parser/tests/select_else_2.out

@@ -1,3 +1,10 @@
+vlib/v/parser/tests/select_else_2.vv:9:3: notice: `>` is deprecated and will soon be forbidden - just state the timeout in nanoseconds
+    7 |             println(b)
+    8 |         }
+    9 |         > 30 * time.millisecond {
+      |         ^
+   10 |             println('bad')
+   11 |         }
 vlib/v/parser/tests/select_else_2.vv:12:3: error: timeout `> t` and `else` are mutually exclusive `select` keys
    10 |             println('bad')
    11 |         }