tree 54893d0211714fcf3aaa0ac2ff6ac87389b69016
parent 128ea3dce9b8753167f33d0a96bd093a6cbd58b8
author Ian Lance Taylor <iant@golang.org> 1636596912 -0800
committer Ian Lance Taylor <iant@golang.org> 1636662063 +0000

compiler: traverse func subexprs when creating func descriptors

Fix the Create_func_descriptors pass to traverse the subexpressions of
the function in a Call_expression.  There are no subexpressions in the
normal case of calling a function a method directly, but there are
subexpressions when in code like F().M() when F returns an interface type.

Forgetting to traverse the function subexpressions was almost entirely
hidden by the fact that we also created the necessary thunks in
Bound_method_expression::do_flatten and
Interface_field_reference_expression::do_get_backend.  However, when
the thunks were created there, they did not go through the
order_evaluations pass.  This almost always worked, but failed in the
case in which the function being thunked returned multiple results, as
order_evaluations takes the necessary step of moving the
Call_expression into its own statement, and that would not happen when
order_evaluations was not called.  Avoid hiding errors like this by
changing those methods to only lookup the previously created thunk,
rather than creating it if it was not already created.

The test case for this is https://golang.org/cl/363156.

Fixes golang/go#49512

Change-Id: I6b273156f16ed6ed22e600097628a1cb6499de64
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/363274
Trust: Ian Lance Taylor <iant@golang.org>
Trust: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>