Throw an erorr if split is called with the same older and inner var n…

…ame (#7715)

* throw an erorr if split is called with the same older and inner name

* update

* fix naming

* rewording

* add test

---------

Co-authored-by: Steven Johnson <srj@google.com>

src/Func.cpp

@@ -1010,6 +1010,12 @@ void Stage::split(const string &old, const string &outer, const string &inner, c
 
  definition.schedule().touched() = true;
 
+ user_assert(inner != outer) << "In schedule for " << name()
+ << ", can't split " << old << " into "
+ << outer << " and " << inner
+ << " because the new Vars have the same name.\n"
+ << dump_argument_list();
+
  // Check that the new names aren't already in the dims list.
  for (auto &dim : dims) {
  string new_names[2] = {inner, outer};

test/error/CMakeLists.txt

@@ -91,6 +91,7 @@ tests(GROUPS error
  specialize_fail.cpp
  split_inner_wrong_tail_strategy.cpp
  split_non_innermost_predicated.cpp
+ split_same_var_names.cpp
  thread_id_outside_block_id.cpp
  too_many_args.cpp
  tuple_arg_select_undef.cpp

test/error/split_same_var_names.cpp

@@ -0,0 +1,13 @@
+#include "Halide.h"
+
+using namespace Halide;
+
+int main(int argc, char **argv) {
+ Var x;
+ Func f;
+ f(x) = x;
+ f.split(x, x, x, 16, TailStrategy::RoundUp);
+
+ printf("Success!\n");
+ return 0;
+}