Improve argument printing (#87601)

No more "expected tuple but got tuple".  We appropriately
grovel in the list/tuple for the element that mismatched
and report what exactly twinged the failure.

invalid_arguments.cpp is a shitshow so I did something
slapdash to get it not completely horrible.  See
https://github.com/pytorch/pytorch/issues/87514 for more context.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87601
Approved by: https://github.com/Chillee

test/test_native_functions.py

@@ -19,6 +19,46 @@ class IntListWrapperModule(torch.nn.Module):
 
 class TestNativeFunctions(TestCase):
 
+    def _lists_with_str(self):
+        return [
+            ("foo",),
+            (2, "foo"),
+            ("foo", 3),
+            ["foo"],
+            [2, "foo"],
+            ["foo", 3],
+            "foo",
+        ]
+
+    def _test_raises_str_typeerror(self, fn):
+        for arg in self._lists_with_str():
+            self.assertRaisesRegex(TypeError, "str", lambda: fn(arg))
+            try:
+                fn(arg)
+            except TypeError as e:
+                print(e)
+
+    def test_symintlist_error(self):
+        x = torch.randn(1)
+        self._test_raises_str_typeerror(lambda arg: torch._C._nn.pad(x, arg))
+
+    def test_vararg_symintlist_error(self):
+        self._test_raises_str_typeerror(lambda arg: torch.rand(arg))
+        self._test_raises_str_typeerror(lambda arg: torch.rand(*arg))
+
+    def test_symintlist_error_with_overload_but_is_unique(self):
+        x = torch.randn(1)
+        y = torch.randn(1)
+        self._test_raises_str_typeerror(lambda arg: x.set_(y, 0, arg))
+
+    def test_symintlist_error_with_overload(self):
+        x = torch.randn(1)
+        self._test_raises_str_typeerror(lambda arg: x.view(arg))
+
+    def test_intlist_error_with_overload(self):
+        x = torch.randn(1)
+        self._test_raises_str_typeerror(lambda arg: torch._C._nn.pad(x, arg))
+
     #
     # optional float list
     #
@@ -113,7 +153,7 @@ class TestNativeFunctions(TestCase):
         self.do_test_optional_intlist_with_module(fake_module)
 
     def test_optional_intlist_invalid(self):
-        with self.assertRaisesRegex(TypeError, "must be .* not"):
+        with self.assertRaisesRegex(TypeError, "must be .* but found"):
             IntListWrapperModule()(torch.zeros(1), [0.5])
 
         with self.assertRaisesRegex(RuntimeError, "value of type .* instead found type"):