checker/table: generic fixes

vlib/v/checker/checker.v

@@ -888,13 +888,6 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 		c.error('unknown function: $fn_name', call_expr.pos)
 		return table.void_type
 	}
-	if call_expr.generic_type != table.void_type && f.return_type != 0 { // table.t_type {
-		// Handle `foo<T>() T` => `foo<int>() int` => return int
-		sym := c.table.get_type_symbol(f.return_type)
-		if sym.name == 'T' {
-			return call_expr.generic_type
-		}
-	}
 	if !found_in_args && call_expr.mod in ['builtin', 'main'] {
 		scope := c.file.scope.innermost(call_expr.pos.pos)
 		if _ := scope.find_var(fn_name) {
@@ -988,6 +981,13 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 				call_expr.pos)
 		}
 	}
+	if call_expr.generic_type != table.void_type && f.return_type != 0 { // table.t_type {
+		// Handle `foo<T>() T` => `foo<int>() int` => return int
+		sym := c.table.get_type_symbol(f.return_type)
+		if sym.name == 'T' {
+			return call_expr.generic_type
+		}
+	}
 	return f.return_type
 }
 

vlib/v/table/table.v

@@ -572,6 +572,9 @@ pub fn (table &Table) qualify_module(mod, file_path string) string {
 
 pub fn (table &Table) register_fn_gen_type(fn_name string, typ Type) {
 	mut a := table.fn_gen_types[fn_name]
+	if typ in a {
+		return
+	}
 	a << typ
 	table.fn_gen_types[fn_name] = a
 }

vlib/v/tests/generic_test.v

@@ -7,7 +7,9 @@ fn simple<T>(p T) T {
 
 fn test_generic_fn() {
 	assert simple<int>(1) == 1
+	assert simple<int>(1 + 0) == 1
 	assert simple<string>('g') == 'g'
+	assert simple<string>('g') + 'h' == 'gh'
 }
 
 /*