From f995aa35ea168df3edf67bd1787791219b8b2519 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Sun, 15 Nov 2020 11:13:35 +0200
Subject: [PATCH] checker: add a check for `x := math.sin<f64>(0)`

---
 vlib/v/ast/ast.v                                       |  1 +
 vlib/v/checker/checker.v                               |  3 +++
 ...nerics_non_generic_fn_called_like_a_generic_one.out |  7 +++++++
 ...enerics_non_generic_fn_called_like_a_generic_one.vv |  6 ++++++
 vlib/v/parser/fn.v                                     |  3 +++
 vlib/v/table/atypes.v                                  | 10 ++++++++++
 6 files changed, 30 insertions(+)
 create mode 100644 vlib/v/checker/tests/generics_non_generic_fn_called_like_a_generic_one.out
 create mode 100644 vlib/v/checker/tests/generics_non_generic_fn_called_like_a_generic_one.vv

diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index 05619e4be0..987f7e88cf 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -306,6 +306,7 @@ pub mut:
 	return_type        table.Type
 	should_be_skipped  bool
 	generic_type       table.Type // TODO array, to support multiple types
+	generic_list_pos   token.Position
 	free_receiver      bool // true if the receiver expression needs to be freed
 	// autofree_pregen    string
 	// autofree_vars      []AutofreeArgVar
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 9347a56c2d..12e0e91159 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1595,6 +1595,9 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 			}
 		}
 	}
+	if call_expr.generic_type.is_full() && !f.is_generic {
+		c.error('a non generic function called like a generic one', call_expr.generic_list_pos)
+	}
 	if f.is_generic {
 		return call_expr.return_type
 	}
diff --git a/vlib/v/checker/tests/generics_non_generic_fn_called_like_a_generic_one.out b/vlib/v/checker/tests/generics_non_generic_fn_called_like_a_generic_one.out
new file mode 100644
index 0000000000..0c2c68e5eb
--- /dev/null
+++ b/vlib/v/checker/tests/generics_non_generic_fn_called_like_a_generic_one.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/generics_non_generic_fn_called_like_a_generic_one.vv:4:15: error: a non generic function called like a generic one
+    2 | 
+    3 | fn main() {
+    4 |     x := math.sin<f64>(1.0)
+      |                  ~~~~~
+    5 |     println(x)
+    6 | }
diff --git a/vlib/v/checker/tests/generics_non_generic_fn_called_like_a_generic_one.vv b/vlib/v/checker/tests/generics_non_generic_fn_called_like_a_generic_one.vv
new file mode 100644
index 0000000000..d25ddd1bc6
--- /dev/null
+++ b/vlib/v/checker/tests/generics_non_generic_fn_called_like_a_generic_one.vv
@@ -0,0 +1,6 @@
+import math
+
+fn main() {
+	x := math.sin<f64>(1.0)
+	println(x)
+}
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index b66729be87..dd8a34b7c5 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -27,12 +27,14 @@ pub fn (mut p Parser) call_expr(language table.Language, mod string) ast.CallExp
 		or_kind = .block
 	}
 	mut generic_type := table.void_type
+	mut generic_list_pos := p.tok.position()
 	if p.tok.kind == .lt {
 		// `foo<int>(10)`
 		p.next() // `<`
 		p.expr_mod = ''
 		generic_type = p.parse_type()
 		p.check(.gt) // `>`
+		generic_list_pos = generic_list_pos.extend(p.prev_tok.position())
 		// In case of `foo<T>()`
 		// T is unwrapped and registered in the checker.
 		if !generic_type.has_flag(.generic) {
@@ -98,6 +100,7 @@ pub fn (mut p Parser) call_expr(language table.Language, mod string) ast.CallExp
 		pos: pos
 		language: language
 		generic_type: generic_type
+		generic_list_pos: generic_list_pos
 		or_block: ast.OrExpr{
 			stmts: or_stmts
 			kind: or_kind
diff --git a/vlib/v/table/atypes.v b/vlib/v/table/atypes.v
index 433a61f0dd..3879a8a91c 100644
--- a/vlib/v/table/atypes.v
+++ b/vlib/v/table/atypes.v
@@ -106,6 +106,16 @@ pub fn (t Type) idx() int {
 	return u16(t) & 0xffff
 }
 
+[inline]
+pub fn (t Type) is_void() bool {
+	return t == void_type
+}
+
+[inline]
+pub fn (t Type) is_full() bool {
+	return t != 0 && t != void_type
+}
+
 // return nr_muls for `t`
 [inline]
 pub fn (t Type) nr_muls() int {