Add --enable-debug-build option to extconf.rb

ext/fiddle/extconf.rb

@@ -3,6 +3,47 @@
 
 # :stopdoc:
 
+def gcc?
+  RbConfig::CONFIG["GCC"] == "yes"
+end
+
+def disable_optimization_build_flag(flags)
+  if gcc?
+    expanded_flags = RbConfig.expand(flags.dup)
+    optimization_option_pattern = /(^|\s)?-O\d(\s|$)?/
+    if optimization_option_pattern.match?(expanded_flags)
+      expanded_flags.gsub(optimization_option_pattern, '\\1-Og\\2')
+    else
+      flags + " -Og"
+    end
+  else
+    flags
+  end
+end
+
+def enable_debug_build_flag(flags)
+  if gcc?
+    expanded_flags = RbConfig.expand(flags.dup)
+    debug_option_pattern = /(^|\s)-g(?:gdb)?\d?(\s|$)/
+    if debug_option_pattern.match?(expanded_flags)
+      expanded_flags.gsub(debug_option_pattern, '\\1-ggdb3\\2')
+    else
+      flags + " -ggdb3"
+    end
+  else
+    flags
+  end
+end
+
+checking_for(checking_message("--enable-debug-build option")) do
+  enable_debug_build = enable_config("debug-build", false)
+  if enable_debug_build
+    $CFLAGS = disable_optimization_build_flag($CFLAGS)
+    $CFLAGS = enable_debug_build_flag($CFLAGS)
+  end
+  enable_debug_build
+end
+
 libffi_version = nil
 have_libffi = false
 bundle = enable_config('bundled-libffi')