Change official debug builds to release + dcheck_always_on (issue #1961)

tools/gn_args.py

@@ -195,6 +195,10 @@ def ValidateArgs(args):
     if not dcheck_always_on:
       msg('is_asan=true recommends dcheck_always_on=true')
 
+  # Official build requires Release builds.
+  if is_official_build:
+    assert not is_debug, "is_official_build=true requires is_debug=false"
+
   if platform == 'windows':
     # Official builds should not use /DEBUG:FASTLINK.
     if is_official_build:
@@ -265,7 +269,18 @@ def GetConfigArgs(args, is_debug, is_x64):
   """
   Return merged GN args for the configuration and validate.
   """
-  result = MergeDicts(args, {
+  add_args = {}
+
+  # Cannot create is_official_build=true is_debug=true builds.
+  # This restriction is enforced in //build/config/BUILDCONFIG.gn.
+  # Instead, our "official Debug" build is a Release build with dchecks and
+  # symbols. Symbols will be generated by default for official builds; see the
+  # definition of 'symbol_level' in //build/config/compiler/compiler.gni.
+  if is_debug and GetArgValue(args, 'is_official_build'):
+    is_debug = False
+    add_args['dcheck_always_on'] = True
+
+  result = MergeDicts(args, add_args, {
     'is_debug': is_debug,
     'target_cpu': 'x64' if is_x64 else 'x86',
   })
@@ -281,20 +296,22 @@ def GetAllPlatformConfigs(build_args):
   # Merged args without validation.
   args = GetMergedArgs(build_args)
 
+  create_debug = True
+
   # Don't create debug directories for asan builds.
-  is_asan = GetArgValue(args, 'is_asan')
-  if is_asan:
-    msg('Only generating Release configuration due to is_asan=true')
+  if GetArgValue(args, 'is_asan'):
+    create_debug = False
+    msg('Not generating Debug configuration due to is_asan=true')
 
   # Always create x64 configs.
-  if not is_asan:
+  if create_debug:
     result['Debug_GN_x64'] = GetConfigArgs(args, True, True)
   result['Release_GN_x64'] = GetConfigArgs(args, False, True)
 
   # Create x86 configs on Windows and on Linux when using the sysroot.
   if platform == 'windows' or \
     (platform == 'linux' and GetArgValue(args, 'use_sysroot') == True):
-    if not is_asan:
+    if create_debug:
       result['Debug_GN_x86'] = GetConfigArgs(args, True, False)
     result['Release_GN_x86'] = GetConfigArgs(args, False, False)