linux: reenable symbols in backtraces in debug builds

build/common.gypi

 # Copyright (c) 2009 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   'variables': {
     # .gyp files should set chromium_code to 1 if they build Chromium-specific
@@ skipping 568 matching lines @@
           'no_strict_aliasing%': 0,
           'conditions': [['OS=="linux"', {'werror%': '-Werror',}],
                          ['OS=="freebsd"', {'werror%': '',}],
                          ['OS=="openbsd"', {'werror%': '',}],
           ],
         },
         'cflags': [
           '<(werror)',  # See note above about the werror variable.
           '-pthread',
           '-fno-exceptions',
-          '-fvisibility=hidden',
           '-Wall',
           '-D_FILE_OFFSET_BITS=64',
         ],
         'cflags_cc': [
           '-fno-rtti',
           '-fno-threadsafe-statics',
           # Make inline functions have hidden visiblity by default.
           # Surprisingly, not covered by -fvisibility=hidden.
           '-fvisibility-inlines-hidden',
         ],
@@ skipping 91 matching lines @@
             },
             'cflags': [
               '-O>(release_optimize)',
               # Don't emit the GCC version ident directives, they just end up
               # in the .comment section taking up binary size.
               '-fno-ident',
               # Put data and code in their own sections, so that unused symbols
               # can be removed at link time with --gc-sections.
               '-fdata-sections',
               '-ffunction-sections',
+              # Don't export any symbols (for example, to plugins we dlopen()).
+              # This must be in Release builds only because otherwise we don't
+              # get backtraces.
+              '-fvisibility=hidden',
               # We don't use exceptions.  The eh_frame section is used for those
               # and for symbolizing backtraces.  By passing this flag we drop
               # the eh_frame section completely, we shaving off 2.5mb from
               # our resulting binary.
               '-fno-asynchronous-unwind-tables',
             ],
             'ldflags': [
               '-Wl,--gc-sections',
             ],
           },
@@ skipping 430 matching lines @@
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }
 
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