Re: Pretty printers for versioned namespace

[Jonathan Wakely]

On 19/01/17 22:01 +0100, François Dumont wrote:

On 10/01/2017 13:39, Jonathan Wakely wrote:

I've committed the attached patch, which passes the tests for the
default configuration and the versioned namespace configuration.

I added another helper function, strip_versioned_namespace, which is
more expressive than doing typename.replace(vers_nsp, '') everywhere.
I've also renamed vers_nsp to _versioned_namespace (using the naming
convention for global variables private to the module). I've added
checks so that if that variable is None then the extra printers and
special cases for the versioned namespace are skipped. That's not
currently used, but it would allow us to optimise things later if
needed.

Very nice feature indeed, see below.

I also needed to update the new SharedPtrMethodsMatcher to add
"(__\d+)?" to the regular expression.

@@ -1392,47 +1406,54 @@ def register_type_printers(obj):
   add_one_type_printer(obj, 'discard_block_engine', 'ranlux48')
   add_one_type_printer(obj, 'shuffle_order_engine', 'knuth_b')

+    # Consider optional versioned namespace
+    opt_nsp = '(' + vers_nsp + ')?'
+
   # Do not show defaulted template arguments in class templates
   add_one_template_type_printer(obj, 'unique_ptr<T>',
-            'unique_ptr<(.*), std::default_delete<\\1 ?> >',
-            'unique_ptr<{1}>')

+ '{0}unique_ptr<(.*), std::{0}default_delete<\\2 ?>

'.format(opt_nsp),

+        'unique_ptr<{2}>')

This is ugly. Mixing python string formatting with regular expressions
makes it harder to read, and is inconsistent with how the versioned
namespace is handled elsewhere. In Printer.add_version and
add_one_type_printer we just register two names, one using std:: and
one using std::__7::. We can do the same for the template type
printers.

Yes, your approach is much nicer even if it results in more type printer registered.

My plan was to submit the attached patch but this doesn't work as the python module seems to be loaded before libstdc++.so. If you know a way to test for versioned namespace before starting registering printers this patch might still be useful. Otherwise I will just forget it.

See the attached patch, which decides at configure-time whether to
enable the versioned namespace printers or not. This is what I had in
mind.




diff --git a/libstdc++-v3/python/Makefile.am b/libstdc++-v3/python/Makefile.am
index 80790e2..5d19d3d 100644
--- a/libstdc++-v3/python/Makefile.am
+++ b/libstdc++-v3/python/Makefile.am
@@ -29,6 +29,12 @@ else
 pythondir = $(datadir)/gcc-$(gcc_version)/python
 endif
 
+if ENABLE_SYMVERS_GNU_NAMESPACE
+use_versioned_namespace = True
+else
+use_versioned_namespace = False
+endif
+
 all-local: gdb.py
 
 nobase_python_DATA = \
@@ -39,7 +45,9 @@ nobase_python_DATA = \
 
 gdb.py: hook.in Makefile
        sed -e 's,@pythondir@,$(pythondir),' \
-           -e 's,@toolexeclibdir@,$(toolexeclibdir),' < $(srcdir)/hook.in > $@
+           -e 's,@toolexeclibdir@,$(toolexeclibdir),' \
+           -e 's,@use_versioned_namespace@,$(use_versioned_namespace),' \
+           < $(srcdir)/hook.in > $@
 
 install-data-local: gdb.py
        @$(mkdir_p) $(DESTDIR)$(toolexeclibdir)
diff --git a/libstdc++-v3/python/hook.in b/libstdc++-v3/python/hook.in
index b82604a6c..1b3a577 100644
--- a/libstdc++-v3/python/hook.in
+++ b/libstdc++-v3/python/hook.in
@@ -58,4 +58,4 @@ if gdb.current_objfile () is not None:
 # Call a function as a plain import would not execute body of the included file
 # on repeated reloads of this object file.
 from libstdcxx.v6 import register_libstdcxx_printers
-register_libstdcxx_printers(gdb.current_objfile())
+register_libstdcxx_printers(gdb.current_objfile(), @use_versioned_namespace@)
diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py 
b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 36dd81d..4a7d117 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -1482,7 +1482,7 @@ def register_type_printers(obj):
             'experimental::fundamentals_v\d::basic_string_view<(.*), 
std::char_traits<\\1> >',
             'experimental::basic_string_view<\\1>')
 
-def register_libstdcxx_printers (obj):
+def register_libstdcxx_printers (obj, use_versioned_namespace = False):
     "Register libstdc++ pretty-printers with objfile Obj."
 
     global _use_gdb_pp
@@ -1495,6 +1495,9 @@ def register_libstdcxx_printers (obj):
             obj = gdb
         obj.pretty_printers.append(libstdcxx_printer)
 
+    if not use_versioned_namespace:
+        _versioned_namespace = None
+
     register_type_printers(obj)
 
 def build_libstdcxx_dictionary ():