Go patch committed: Treat void_type_node as zero sized

[Ian Lance Taylor <iant at golang dot org>]

The interface between the Go frontend and the GCC middle-end sets the
return type of a function type that returns a zero-sized value to
void_type_node.  This was done to avoid confusion with libffi, for PR
72814.  However, there are various ways that Go code can correctly use
a zero-sized type returned by a function, and at least one of those
caused a compiler crash (https://golang.org/issue/22305).  This patch
adds some checks for void_type_node to the code that already checks
for a zero-sized type.  Bootstrapped and ran Go testsuite on
x86_64-pc-linux-gnu.  Committed to mainline.

Ian


2018-02-02  Ian Lance Taylor  <iant@golang.org>

* go-gcc.cc (Gcc_backend::type_size): Return 0 for
void_type_node.
(Gcc_backend::convert_expression): Don't convert if the type of
expr_tree is void_type_node.
(Gcc_backend::array_index_expression): Don't index if the type of
the array expression is void_type_node.
(Gcc_backend::init_statement): Don't initialize if the type of the
initializer expression is void_type_node.
(Gcc_backend::assignment_statement): Don't assign if the type of
either the left or right hand side is void_type_node.
(Gcc_backend::temporary_variable): Don't initialize if the type of
the initializer expression is void_type_node.

Attachment: patch.txt
Description: Text document