From 2785a5bf65246c8dcdb3cf7aa74cb053e1e6a326 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Mon, 15 Jun 2020 13:10:45 +0800
Subject: [PATCH] checker: check return_duplicate_with_none (closes #5363)

---
 vlib/v/ast/ast.v                                         | 6 +++++-
 vlib/v/checker/checker.v                                 | 2 +-
 .../v/checker/tests/return_duplicate_with_none_err_a.out | 7 +++++++
 vlib/v/checker/tests/return_duplicate_with_none_err_a.vv | 9 +++++++++
 .../v/checker/tests/return_duplicate_with_none_err_b.out | 7 +++++++
 vlib/v/checker/tests/return_duplicate_with_none_err_b.vv | 9 +++++++++
 vlib/v/parser/pratt.v                                    | 5 ++++-
 7 files changed, 42 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/checker/tests/return_duplicate_with_none_err_a.out
 create mode 100644 vlib/v/checker/tests/return_duplicate_with_none_err_a.vv
 create mode 100644 vlib/v/checker/tests/return_duplicate_with_none_err_b.out
 create mode 100644 vlib/v/checker/tests/return_duplicate_with_none_err_b.vv

diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index 8ae1bc4966..abd456400d 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -798,7 +798,8 @@ pub mut:
 
 pub struct None {
 pub:
-	foo int // todo
+	pos  token.Position
+	foo  int // todo
 }
 
 [inline]
@@ -874,6 +875,9 @@ pub fn (expr Expr) position() token.Position {
 		MatchExpr {
 			return it.pos
 		}
+		None {
+			return it.pos
+		}
 		PostfixExpr {
 			return it.pos
 		}
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 9434dd9fd4..4db86be2e4 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1793,7 +1793,7 @@ fn (mut c Checker) stmts(stmts []ast.Stmt) {
 		c.stmt(stmt)
 	}
 	if unreachable.line_nr >= 0 {
-		c.warn('unreachable code', unreachable)
+		c.error('unreachable code', unreachable)
 	}
 	c.scope_returns = false
 	c.expected_type = table.void_type
diff --git a/vlib/v/checker/tests/return_duplicate_with_none_err_a.out b/vlib/v/checker/tests/return_duplicate_with_none_err_a.out
new file mode 100644
index 0000000000..5907a63114
--- /dev/null
+++ b/vlib/v/checker/tests/return_duplicate_with_none_err_a.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/return_duplicate_with_none_err_a.v:3:2: error: unreachable code
+    1 | fn f() ?bool {
+    2 |     return true
+    3 |     return none
+      |     ~~~~~~~~~~~
+    4 | }
+    5 | fn main() {
diff --git a/vlib/v/checker/tests/return_duplicate_with_none_err_a.vv b/vlib/v/checker/tests/return_duplicate_with_none_err_a.vv
new file mode 100644
index 0000000000..c356eb89fa
--- /dev/null
+++ b/vlib/v/checker/tests/return_duplicate_with_none_err_a.vv
@@ -0,0 +1,9 @@
+fn f() ?bool {
+	return true
+	return none
+}
+fn main() {
+	f() or {
+		println('fail')
+	}
+}
diff --git a/vlib/v/checker/tests/return_duplicate_with_none_err_b.out b/vlib/v/checker/tests/return_duplicate_with_none_err_b.out
new file mode 100644
index 0000000000..c3f15574c9
--- /dev/null
+++ b/vlib/v/checker/tests/return_duplicate_with_none_err_b.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/return_duplicate_with_none_err_b.v:3:2: error: unreachable code
+    1 | fn f() ?bool {
+    2 |     return none
+    3 |     return true
+      |     ~~~~~~~~~~~
+    4 | }
+    5 | fn main() {
diff --git a/vlib/v/checker/tests/return_duplicate_with_none_err_b.vv b/vlib/v/checker/tests/return_duplicate_with_none_err_b.vv
new file mode 100644
index 0000000000..aaf39a1525
--- /dev/null
+++ b/vlib/v/checker/tests/return_duplicate_with_none_err_b.vv
@@ -0,0 +1,9 @@
+fn f() ?bool {
+	return none
+	return true
+}
+fn main() {
+	f() or {
+		println('fail')
+	}
+}
diff --git a/vlib/v/parser/pratt.v b/vlib/v/parser/pratt.v
index e9a7e0eb63..e43d9aa6a5 100644
--- a/vlib/v/parser/pratt.v
+++ b/vlib/v/parser/pratt.v
@@ -73,8 +73,11 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 			}
 		}
 		.key_none {
+			pos := p.tok.position()
 			p.next()
-			node = ast.None{}
+			node = ast.None{
+				pos: pos
+			}
 		}
 		.key_sizeof {
 			p.next() // sizeof