compiler, runtime: better stack trace for `go f()` where f is nil
The test for this is TestGoNil in the runtime package, which we don't
run yet but will run with a subsequent gotools patch.
Updates golang/go#8045
Change-Id: I930224cd1a7800e6cbc3d13bd75bb9cb840b4b55
Reviewed-on: https://go-review.googlesource.com/46392
Reviewed-by: Than McIntosh <thanm@google.com>
diff --git a/go/gogo.h b/go/gogo.h
index c3e3f30..a04a1a3 100644
--- a/go/gogo.h
+++ b/go/gogo.h
@@ -3379,6 +3379,9 @@
// Division by zero.
static const int RUNTIME_ERROR_DIVISION_BY_ZERO = 10;
+// Go statement with nil function.
+static const int RUNTIME_ERROR_GO_NIL = 11;
+
// This is used by some of the langhooks.
extern Gogo* go_get_gogo();
diff --git a/go/statements.cc b/go/statements.cc
index 7a448d7..e592176 100644
--- a/go/statements.cc
+++ b/go/statements.cc
@@ -2201,6 +2201,15 @@
Location location = this->location();
+ bool is_constant_function = this->is_constant_function();
+ Temporary_statement* fn_temp = NULL;
+ if (!is_constant_function)
+ {
+ fn_temp = Statement::make_temporary(NULL, fn, location);
+ block->insert_statement_before(block->statements()->size() - 1, fn_temp);
+ fn = Expression::make_temporary_reference(fn_temp, location);
+ }
+
std::string thunk_name = Gogo::thunk_name();
// Build the thunk.
@@ -2212,7 +2221,7 @@
// argument to the thunk.
Expression_list* vals = new Expression_list();
- if (!this->is_constant_function())
+ if (!is_constant_function)
vals->push_back(fn);
if (interface_method != NULL)
@@ -2238,6 +2247,23 @@
// Allocate the initialized struct on the heap.
constructor = Expression::make_heap_expression(constructor, location);
+ // Throw an error if the function is nil. This is so that for `go
+ // nil` we get a backtrace from the go statement, rather than a
+ // useless backtrace from the brand new goroutine.
+ Expression* param = constructor;
+ if (!is_constant_function)
+ {
+ fn = Expression::make_temporary_reference(fn_temp, location);
+ Expression* nil = Expression::make_nil(location);
+ Expression* isnil = Expression::make_binary(OPERATOR_EQEQ, fn, nil,
+ location);
+ Expression* crash = gogo->runtime_error(RUNTIME_ERROR_GO_NIL, location);
+ crash = Expression::make_conditional(isnil, crash,
+ Expression::make_nil(location),
+ location);
+ param = Expression::make_compound(crash, constructor, location);
+ }
+
// Look up the thunk.
Named_object* named_thunk = gogo->lookup(thunk_name, NULL);
go_assert(named_thunk != NULL && named_thunk->is_function());
@@ -2246,7 +2272,7 @@
Expression* func = Expression::make_func_reference(named_thunk, NULL,
location);
Expression_list* params = new Expression_list();
- params->push_back(constructor);
+ params->push_back(param);
Call_expression* call = Expression::make_call(func, params, false, location);
// Build the simple go or defer statement.
diff --git a/libgo/runtime/go-runtime-error.c b/libgo/runtime/go-runtime-error.c
index f5ab4f9..4f563fc 100644
--- a/libgo/runtime/go-runtime-error.c
+++ b/libgo/runtime/go-runtime-error.c
@@ -49,7 +49,10 @@
MAKE_CHAN_OUT_OF_BOUNDS = 9,
/* Integer division by zero. */
- DIVISION_BY_ZERO = 10
+ DIVISION_BY_ZERO = 10,
+
+ /* Go statement with nil function. */
+ GO_NIL = 11
};
extern void __go_runtime_error () __attribute__ ((noreturn));
@@ -84,6 +87,12 @@
case DIVISION_BY_ZERO:
runtime_panicstring ("integer divide by zero");
+ case GO_NIL:
+ /* This one is a throw, rather than a panic. Set throwing to
+ not dump full stacks. */
+ runtime_g()->m->throwing = -1;
+ runtime_throw ("go of nil func value");
+
default:
runtime_panicstring ("unknown runtime error");
}
