Throw Exception for wrong arg type in join method (lcompilers#2364)

* Throw Exception for wrong argtype in join method

* Remove SemanticError from test_str_01.py

* Add reference for test handling join method

* Remove .stdout file

* Run reference test

* Remove unnecessary files

* Include update references

* Update tests/errors/string_01.py

Co-authored-by: Shaikh Ubaid <shaikhubaid769@gmail.com>

* Update test reference

* Remove .stdout file

* Add test for corner cases

* Remove unused import

---------

Co-authored-by: Shaikh Ubaid <shaikhubaid769@gmail.com>

integration_tests/test_str_01.py

@@ -59,6 +59,19 @@ def test_str_join2():
     res:str = a.join(p)
     assert res == "a**b"
 
+def test_str_join_empty_str():
+    a: str
+    a = ""
+    p:list[str] = ["a","b"]
+    res:str = a.join(p)
+    assert res == "ab"
+
+def test_str_join_empty_list():
+    a: str
+    a = "ab"
+    p:list[str] = []
+    res:str = a.join(p)
+    assert res == ""
 
 def test_constant_str_subscript():
     assert "abc"[2] == "c"
@@ -71,6 +84,9 @@ def check():
     test_str_slice()
     test_str_repeat()
     test_str_join()
+    test_str_join2()
+    test_str_join_empty_str()
+    test_str_join_empty_list()
     test_constant_str_subscript()
 
 check()

src/lpython/semantics/python_ast_to_asr.cpp

@@ -34,7 +34,6 @@
 #include <lpython/parser/parser.h>
 #include <libasr/serialization.h>
 
-
 namespace LCompilers::LPython {
 
 namespace CastingUtil {
@@ -6669,15 +6668,21 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
                 throw SemanticError("str.join() takes one argument",
                     loc);
             }
+            ASR::expr_t *arg_sub = args[0].m_value;
+            ASR::ttype_t *arg_sub_type = ASRUtils::expr_type(arg_sub);
+            if(!ASR::is_a<ASR::List_t>(*arg_sub_type)){
+                throw SemanticError("str.join() takes type list only",
+                     loc);
+            }
             fn_call_name = "_lpython_str_join";
             ASR::call_arg_t str_var;
             str_var.loc = loc;
             str_var.m_value = s_var;
-            ASR::call_arg_t passed_int;
-            passed_int.loc = loc;
-            passed_int.m_value = args[0].m_value;
+            ASR::call_arg_t list_of_str;
+            list_of_str.loc = loc;
+            list_of_str.m_value = args[0].m_value;
             fn_args.push_back(al, str_var);
-            fn_args.push_back(al, passed_int);
+            fn_args.push_back(al, list_of_str);
         } else if (attr_name == "find") {
             if (args.size() != 1) {
                 throw SemanticError("str.find() takes one argument",

tests/errors/string_02.py

@@ -0,0 +1,9 @@
+from lpython import i32 
+
+def test_wrong_argument_in_join():
+    x: str = "ab"
+    p: i32 = 1
+    res:str = x.join(p)
+    print(res)
+
+test_wrong_argument_in_join()

tests/reference/asr-string_02-499c9ff.json

@@ -0,0 +1,13 @@
+{
+    "basename": "asr-string_02-499c9ff",
+    "cmd": "lpython --show-asr --no-color {infile} -o {outfile}",
+    "infile": "tests/errors/string_02.py",
+    "infile_hash": "ed6511565e893791a4bd8ea0b4750817bab13cd6dc0731332127bf58",
+    "outfile": null,
+    "outfile_hash": null,
+    "stdout": null,
+    "stdout_hash": null,
+    "stderr": "asr-string_02-499c9ff.stderr",
+    "stderr_hash": "368ba74a1e0d6609f71e6f87f95bd0b6151420c81336e48a172cb613",
+    "returncode": 2
+}

tests/reference/asr-string_02-499c9ff.stderr

@@ -0,0 +1,5 @@
+semantic error: str.join() takes type list only
+ --> tests/errors/string_02.py:6:15
+  |
+6 |     res:str = x.join(p)
+  |               ^^^^^^^^^ 

tests/tests.toml

@@ -650,6 +650,10 @@ asr = true
 filename = "errors/string_01.py"
 asr = true
 
+[[test]]
+filename = "errors/string_02.py"
+asr = true
+
 [[test]]
 filename = "errors/structs_01.py"
 asr = true