Change how arguments passed are counted (Kampfkarren#120)

* add gitattribute to fix .stderr files

* fix arguments count

* fix single-quotes

* assume at least one return value

* update changelog

* add test cases

.gitattributes

@@ -0,0 +1 @@
+*.stderr text eol=lf

CHANGELOG.md

@@ -5,6 +5,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 ### Changed
 - Removed types from `debug.traceback` arguments in the Lua 5.1 standard library
 - Made 4th argument to `CFrame.fromMatrix` optional (#113)
+- Made standard library aware that functions and `...` can return multiple values
 
 ## [0.6.0] - 2020-04-21
 ### Added

selene-lib/src/rules/standard_library.rs

@@ -527,12 +527,32 @@ impl Visitor<'_> for StandardLibraryVisitor<'_> {
             }
         }
 
-        let any_are_vararg = argument_types.iter().any(|(_, argument_type)| {
-            argument_type.as_ref() == Some(&PassedArgumentType::Primitive(ArgumentType::Vararg))
-        });
+        let mut maybe_more_arguments = false;
+
+        if let ast::FunctionArgs::Parentheses { arguments, .. } = function_args {
+            if let Some(ast::punctuated::Pair::End(last)) = arguments.last() {
+                if let ast::Expression::Value { value, .. } = last {
+                    match &**value {
+                        ast::Value::FunctionCall(_) => {
+                            maybe_more_arguments = true;
+                        }
+                        ast::Value::Symbol(token_ref) => {
+                            if let TokenType::Symbol { symbol } = token_ref.token().token_type() {
+                                if symbol == &full_moon::tokenizer::Symbol::Ellipse {
+                                    maybe_more_arguments = true;
+                                }
+                            }
+                        }
+                        _ => {}
+                    }
+                }
+            }
+        };
 
-        if (!any_are_vararg && argument_types.len() < expected_args)
-            || (!vararg && argument_types.len() > max_args)
+        let arguments_length = argument_types.len();
+
+        if (arguments_length < expected_args && !maybe_more_arguments)
+            || (!vararg && arguments_length > max_args)
         {
             self.diagnostics.push(Diagnostic::new(
                 "incorrect_standard_library_use",
@@ -668,6 +688,15 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_assert() {
+        test_lint(
+            StandardLibraryLint::new(()).unwrap(),
+            "standard_library",
+            "assert",
+        );
+    }
+
     #[test]
     fn test_bad_call_signatures() {
         test_lint(

selene-lib/tests/lints/standard_library/assert.lua

@@ -0,0 +1,8 @@
+assert(true, "message")
+assert(call())
+assert(call(), "this is ok")
+assert(...)
+
+assert(true)
+assert(true, "message", call())
+assert(true, "message", ...)

selene-lib/tests/lints/standard_library/assert.std.toml

@@ -0,0 +1,6 @@
+[[assert.args]]
+type = "any"
+
+[[assert.args]]
+type = "string"
+required = "A failed assertion without a message is unhelpful to users."

selene-lib/tests/lints/standard_library/assert.stderr

@@ -0,0 +1,24 @@
+error[incorrect_standard_library_use]: standard library function `assert` requires 2 parameters, 1 passed
+
+   ┌── assert.lua:6:1 ───
+   │
+ 6 │ assert(true)
+   │ ^^^^^^^^^^^^
+   │
+
+error[incorrect_standard_library_use]: standard library function `assert` requires 2 parameters, 3 passed
+
+   ┌── assert.lua:7:1 ───
+   │
+ 7 │ assert(true, "message", call())
+   │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   │
+
+error[incorrect_standard_library_use]: standard library function `assert` requires 2 parameters, 3 passed
+
+   ┌── assert.lua:8:1 ───
+   │
+ 8 │ assert(true, "message", ...)
+   │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   │
+