Go patch committed: Don't crash on f(g()) if g returns a zero-sized value
Commit Message
This patch to the GCC interface of the Go frontend fixes a crash in
f(g()) if g returns a zero-sized value. In that case the GCC
interface modifies g to return void, since GCC's middle-end does not
have solid support for zero-sized values. This patch detects the
f(g()) case and replaces the call to g() with (g(), zero). The test
case for this is https://go.dev/cl/417481. This fixes
https://go.dev/issue/23868. Bootstrapped and ran Go testsuite on
x86_64-pc-linux-gnu. Committed to mainline.
Ian
* go-gcc.cc (Gcc_backend::call_expression): Handle a void
argument, as for f(g()) where g returns a zero-sized type.
1eb1495f7d0fa9b49f6f3c34bbbf4dd1e850607c
@@ -2112,6 +2112,19 @@ Gcc_backend::call_expression(Bfunction*, // containing fcn for call
args[i] = fn_args.at(i)->get_tree();
if (args[i] == error_mark_node)
return this->error_expression();
+ if (TREE_TYPE(args[i]) == void_type_node)
+ {
+ // This can happen for a case like f(g()) where g returns a
+ // zero-sized type, because in that case we've changed g to
+ // return void.
+ tree t = TYPE_ARG_TYPES(TREE_TYPE(TREE_TYPE(fn)));
+ for (size_t j = 0; j < i; ++j)
+ t = TREE_CHAIN(t);
+ tree arg_type = TREE_TYPE(TREE_VALUE(t));
+ args[i] = fold_build2_loc(EXPR_LOCATION(args[i]), COMPOUND_EXPR,
+ arg_type, args[i],
+ build_zero_cst(arg_type));
+ }
}
tree fndecl = fn;