From bd3c9e888d734c570eccd5a1b1b749b0779e9061 Mon Sep 17 00:00:00 2001
From: shove <shove@163.com>
Date: Sun, 18 Sep 2022 01:59:52 +0800
Subject: [PATCH] checker: fix missing checker error for fn abc() u64 { return
 -1 } (fix #15789) (#15795)

---
 vlib/v/checker/return.v                       | 45 +++++++++++++------
 .../tests/fn_return_unsign_type_mismatch.out  | 13 ++++++
 .../tests/fn_return_unsign_type_mismatch.vv   | 12 +++++
 vlib/v/pref/pref.v                            |  2 +-
 4 files changed, 57 insertions(+), 15 deletions(-)
 create mode 100644 vlib/v/checker/tests/fn_return_unsign_type_mismatch.out
 create mode 100644 vlib/v/checker/tests/fn_return_unsign_type_mismatch.vv

diff --git a/vlib/v/checker/return.v b/vlib/v/checker/return.v
index 1711bbab2..16c0d8999 100644
--- a/vlib/v/checker/return.v
+++ b/vlib/v/checker/return.v
@@ -110,26 +110,43 @@ pub fn (mut c Checker) return_stmt(mut node ast.Return) {
 			c.error('cannot use `${c.table.type_to_str(got_typ)}` as type `${c.table.type_to_str(exp_type)}` in return argument',
 				pos)
 		}
-		if node.exprs[expr_idxs[i]] !is ast.ComptimeCall && !c.check_types(got_typ, exp_type) {
+		if node.exprs[expr_idxs[i]] !is ast.ComptimeCall {
 			got_typ_sym := c.table.sym(got_typ)
-			mut exp_typ_sym := c.table.sym(exp_type)
-			if exp_typ_sym.kind == .interface_ {
-				if c.type_implements(got_typ, exp_type, node.pos) {
-					if !got_typ.is_ptr() && !got_typ.is_pointer() && got_typ_sym.kind != .interface_
-						&& !c.inside_unsafe {
-						c.mark_as_referenced(mut &node.exprs[expr_idxs[i]], true)
+			exp_typ_sym := c.table.sym(exp_type)
+			pos := node.exprs[expr_idxs[i]].pos()
+			if c.check_types(got_typ, exp_type) {
+				if exp_type.is_unsigned() && got_typ.is_int_literal() {
+					if node.exprs[expr_idxs[i]] is ast.IntegerLiteral {
+						var := (node.exprs[expr_idxs[i]] as ast.IntegerLiteral).val
+						if var[0] == `-` {
+							c.note('cannot use a negative value as value of type `${c.table.type_to_str(exp_type)}` in return argument',
+								pos)
+						}
+					} else {
+						if node.exprs[expr_idxs[i]] !is ast.Ident {
+							c.note('use signed type `${c.table.type_to_str(got_typ)}` as unsigned type `${c.table.type_to_str(exp_type)}` in return argument may cause unexpected',
+								pos)
+						}
 					}
 				}
-				continue
-			}
-			if got_typ_sym.kind == .function && exp_typ_sym.kind == .function {
-				if (got_typ_sym.info as ast.FnType).is_anon {
+			} else {
+				if exp_typ_sym.kind == .interface_ {
+					if c.type_implements(got_typ, exp_type, node.pos) {
+						if !got_typ.is_ptr() && !got_typ.is_pointer()
+							&& got_typ_sym.kind != .interface_ && !c.inside_unsafe {
+							c.mark_as_referenced(mut &node.exprs[expr_idxs[i]], true)
+						}
+					}
 					continue
 				}
+				if got_typ_sym.kind == .function && exp_typ_sym.kind == .function {
+					if (got_typ_sym.info as ast.FnType).is_anon {
+						continue
+					}
+				}
+				c.error('cannot use `$got_typ_sym.name` as type `${c.table.type_to_str(exp_type)}` in return argument',
+					pos)
 			}
-			pos := node.exprs[expr_idxs[i]].pos()
-			c.error('cannot use `$got_typ_sym.name` as type `${c.table.type_to_str(exp_type)}` in return argument',
-				pos)
 		}
 		if (got_typ.is_ptr() || got_typ.is_pointer())
 			&& (!exp_type.is_ptr() && !exp_type.is_pointer()) {
diff --git a/vlib/v/checker/tests/fn_return_unsign_type_mismatch.out b/vlib/v/checker/tests/fn_return_unsign_type_mismatch.out
new file mode 100644
index 000000000..dd2014753
--- /dev/null
+++ b/vlib/v/checker/tests/fn_return_unsign_type_mismatch.out
@@ -0,0 +1,13 @@
+vlib/v/checker/tests/fn_return_unsign_type_mismatch.vv:2:9: notice: use signed type `int literal` as unsigned type `u64` in return argument may cause unexpected
+    1 | fn foo() u64 {
+    2 |     return -(3 - 1)
+      |            ^
+    3 | }
+    4 |
+vlib/v/checker/tests/fn_return_unsign_type_mismatch.vv:6:9: notice: cannot use a negative value as value of type `u64` in return argument
+    4 | 
+    5 | fn bar() u64 {
+    6 |     return -1
+      |            ~~
+    7 | }
+    8 |
diff --git a/vlib/v/checker/tests/fn_return_unsign_type_mismatch.vv b/vlib/v/checker/tests/fn_return_unsign_type_mismatch.vv
new file mode 100644
index 000000000..1069052f1
--- /dev/null
+++ b/vlib/v/checker/tests/fn_return_unsign_type_mismatch.vv
@@ -0,0 +1,12 @@
+fn foo() u64 {
+	return -(3 - 1)
+}
+
+fn bar() u64 {
+	return -1
+}
+
+fn main() {
+	dump(foo())
+	dump(bar())
+}
diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index b881ddf71..d756a3fec 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -209,7 +209,7 @@ pub mut:
 	cache_manager       vcache.CacheManager
 	gc_mode             GarbageCollectionMode = .unknown // .no_gc, .boehm, .boehm_leak, ...
 	assert_failure_mode AssertFailureMode     // whether to call abort() or print_backtrace() after an assertion failure
-	message_limit       int = 100 // the maximum amount of warnings/errors/notices that will be accumulated
+	message_limit       int = 150 // the maximum amount of warnings/errors/notices that will be accumulated
 	nofloat             bool // for low level code, like kernels: replaces f32 with u32 and f64 with u64
 	// checker settings:
 	checker_match_exhaustive_cutoff_limit int = 12
-- 
2.39.5