Expand tuple types with rest parameters in generic instantiation

Expand tuple types when encountering rest parameters (`...`) during generic instantiation

close #738

Author: xuhuanzy

crates/emmylua_code_analysis/src/compilation/test/generic_test.rs

@@ -1,6 +1,6 @@
 #[cfg(test)]
 mod test {
-    use crate::VirtualWorkspace;
+    use crate::{DiagnosticCode, VirtualWorkspace};
 
     #[test]
     fn test_issue_586() {
@@ -158,4 +158,17 @@ mod test {
         assert_eq!(a_ty, LuaType::Unknown);
     }
     */
+
+    #[test]
+    fn test_issue_738() {
+        let mut ws = VirtualWorkspace::new();
+        ws.def(
+            r#"
+            ---@alias Predicate<A: any[]> fun(...: A): boolean
+            ---@type Predicate<[string, integer, table]>
+            pred = function() end
+            "#,
+        );
+        assert!(ws.check_code_for(DiagnosticCode::ParamTypeNotMatch, r#"pred('hello', 1, {})"#));
+    }
 }

crates/emmylua_code_analysis/src/semantic/generic/instantiate_type_generic.rs

@@ -161,6 +161,17 @@ pub fn instantiate_doc_function(
             },
             _ => {
                 let new_type = instantiate_type_generic(db, origin_param_type, substitutor);
+                // 如果是 rest 参数且实例化后的类型是 tuple, 那么我们将展开 tuple
+                if origin_param.0 == "..." && tpl_func_params.len() == i + 1 {
+                    if let LuaType::Tuple(tuple_type) = &new_type {
+                        let base_index = new_params.len();
+                        for (offset, tuple_element) in tuple_type.get_types().iter().enumerate() {
+                            let param_name = format!("args_{}", base_index + offset);
+                            new_params.push((param_name, Some(tuple_element.clone())));
+                        }
+                        continue;
+                    }
+                }
                 new_params.push((origin_param.0.clone(), Some(new_type)));
             }
         }