Bug in gdb libstdc++ pretty-printers with gcc 8 installed from macports (macOS)

I set up gdb libstdc++ pretty-printers as described in GDB Wiki. But pretty printing didn't work, gdb kept printing raw data.

I changed printers.py to fix it:

--- python/libstdcxx/v6/printers.py.old 2018-10-13 13:57:11.000000000 +0300
+++ python/libstdcxx/v6/printers.py 2018-10-13 14:35:55.000000000 +0300
@@ -1306,2 +1306,4 @@
     def add(self, name, function):
+        if (name.startswith('std::')):
+            self.add(name[5:], function)
         # A small sanity check.

The patch makes Printer handle std::xxx and xxx equally (e.g. std::vector and vector). The patch helped!

Why did it help? Where is the bug? Used gdb 8.0.1, gcc 8.2.0 installed via macports.

Solution

This is a known issue on OS X but I'm unable to debug it myself, as I don't use OS X.

The problem seems to be related to the debug info that GCC outputs into OS X binaries. On OS X the types shown in the debug info do not match what the pretty printers expect.