gdb/selftest-arch: Make register_test_foreach_arch generate arch tests lazily

The register_test_foreach_arch is used to instantiate a given selftest
for all architectures supported by GDB.  It is used in many _initialize_*
functions (under initialize_all_files, called by gdb_init).

Because the call is done during GDB's initialization, and because there
is no guaranty about the order in which all the _initialize_* functions
are executed, when register_test_foreach_arch is called, GDB is not
fully initialized.  Specifically, when a particular initialize function
is executed, only the architectures registered at that point are listed
by gdbarch_printable_names.

As a consequence, the list of selftest effectively executed depends on
the order the _initialize_* functions are called.  This can be observed
with the following:

    $ ./gdb/gdb \
        -data-directory ./gdb/data-directory \
        -quiet -batch -ex "maint selftest" 2>&1 \
        | grep -E "Ran [0-9]+ unit tests"
    Ran 145 unit tests, 0 failed
    $ GDB_REVERSE_INIT_FUNCTIONS=1 ./gdb/gdb \
        -data-directory ./gdb/data-directory \
        -quiet -batch -ex "maint selftest" 2>&1 \
        | grep -E "Ran [0-9]+ unit tests"
    Ran 82 unit tests, 0 failed

To fix this, make register_test_foreach_arch register a lazy selftest
generator.  This way when the test generator is eventually executed, all
architectures are registered and we do not have a dependency on the
order the initialize functions are executed in.

Tested on x86_64-linux

Change-Id: I88eefebf7d372ad672f42d3a103e89354bc8a925

1 files changed, 21 insertions, 8 deletions

diff --git a/gdb/selftest-arch.c b/gdb/selftest-arch.c
index 1375838b0c2..f434da718d5 100644
--- a/gdb/selftest-arch.c
+++ b/gdb/selftest-arch.c
@@ -49,14 +49,15 @@ static bool skip_arch (const char *arch)
   return false;
 }
 
-/* Register a kind of selftest that calls the test function once for each
-   gdbarch known to GDB.  */
+/* Generate a selftest for each gdbarch known to GDB.  */
 
-void
-register_test_foreach_arch (const std::string &name,
-			    self_test_foreach_arch_function *function)
+static std::vector<selftest>
+foreach_arch_test_generator (const std::string &name,
+			     self_test_foreach_arch_function *function)
 {
+  std::vector<selftest> tests;
   std::vector<const char *> arches = gdbarch_printable_names ();
+  tests.reserve (arches.size ());
   for (const char *arch : arches)
     {
       if (skip_arch (arch))
@@ -73,10 +74,22 @@ register_test_foreach_arch (const std::string &name,
 	     reset ();
 	   });
 
-      std::string test_name
-	= name + std::string ("::") + std::string (arch);
-      register_test (test_name, test_fn);
+      tests.emplace_back (string_printf ("%s::%s", name.c_str (), arch),
+			  test_fn);
     }
+  return tests;
+}
+
+/* See selftest-arch.h.  */
+
+void
+register_test_foreach_arch (const std::string &name,
+			    self_test_foreach_arch_function *function)
+{
+  add_lazy_generator ([=] ()
+		      {
+		        return foreach_arch_test_generator (name, function);
+		      });
 }
 
 void