Use gdb:array_view in call_function_by_hand & friends

This replaces a few uses of pointer+length with gdb::array_view, in
call_function_by_hand and related code.

Unfortunately, due to -Wnarrowing, there are places where we can't
brace-initialize an gdb::array_view without an ugly-ish cast.  To
avoid the cast, this patch introduces a gdb::make_array_view function.
Unit tests included.

This patch in isolation may not look so interesting, due to
gdb::make_array_view uses, but I think it's still worth it.  Some of
the gdb::make_array_view calls disappear down the series, and others
could be eliminated with more (non-trivial) gdb::array_view
detangling/conversion (e.g. code around eval_call).  See this as a "we
have to start somewhere" patch.

gdb/ChangeLog:
2018-11-21  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (ada_evaluate_subexp): Adjust to pass an array_view.
	* common/array-view.h (make_array_view): New.
	* compile/compile-object-run.c (compile_object_run): Adjust to
	pass an array_view.
	* elfread.c (elf_gnu_ifunc_resolve_addr): Adjust.
	* eval.c (eval_call): Adjust to pass an array_view.
	(evaluate_subexp_standard): Adjust to pass an array_view.
	* gcore.c (call_target_sbrk): Adjust to pass an array_view.
	* guile/scm-value.c (gdbscm_value_call): Likewise.
	* infcall.c (push_dummy_code): Replace pointer + size parameters
	with an array_view parameter.
	(call_function_by_hand, call_function_by_hand_dummy): Likewise and
	adjust.
	* infcall.h: Include "common/array-view.h".
	(call_function_by_hand, call_function_by_hand_dummy): Replace
	pointer + size parameters with an array_view parameter.
	* linux-fork.c (inferior_call_waitpid): Adjust to use array_view.
	* linux-tdep.c (linux_infcall_mmap): Likewise.
	* objc-lang.c (lookup_objc_class, lookup_child_selector)
	(value_nsstring, print_object_command): Likewise.
	* python/py-value.c (valpy_call): Likewise.
	* rust-lang.c (rust_evaluate_funcall): Likewise.
	* spu-tdep.c (flush_ea_cache): Likewise.
	* valarith.c (value_x_binop, value_x_unop): Likewise.
	* valops.c (value_allocate_space_in_inferior): Likewise.
	* unittests/array-view-selftests.c (run_tests): Add
	gdb::make_array_view test.

1 files changed, 3 insertions, 4 deletions

diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c
index 74d5c19..0f87d97 100644
--- a/gdb/linux-fork.c
+++ b/gdb/linux-fork.c
@@ -456,7 +456,7 @@ inferior_call_waitpid (ptid_t pptid, int pid)
 {
   struct objfile *waitpid_objf;
   struct value *waitpid_fn = NULL;
-  struct value *argv[4], *retv;
+  struct value *argv[3], *retv;
   struct gdbarch *gdbarch = get_current_arch ();
   struct fork_info *oldfp = NULL, *newfp = NULL;
   struct cleanup *old_cleanup;
@@ -490,9 +490,8 @@ inferior_call_waitpid (ptid_t pptid, int pid)
   argv[0] = value_from_longest (builtin_type (gdbarch)->builtin_int, pid);
   argv[1] = value_from_pointer (builtin_type (gdbarch)->builtin_data_ptr, 0);
   argv[2] = value_from_longest (builtin_type (gdbarch)->builtin_int, 0);
-  argv[3] = 0;
 
-  retv = call_function_by_hand (waitpid_fn, NULL, 3, argv);
+  retv = call_function_by_hand (waitpid_fn, NULL, argv);
   if (value_as_long (retv) < 0)
     goto out;
 
@@ -704,7 +703,7 @@ checkpoint_command (const char *args, int from_tty)
     scoped_restore save_pid
       = make_scoped_restore (&checkpointing_pid, inferior_ptid.pid ());
 
-    ret = call_function_by_hand (fork_fn, NULL, 0, &ret);
+    ret = call_function_by_hand (fork_fn, NULL, {});
   }
 
   if (!ret)	/* Probably can't happen.  */