Codechange: Don't use cpp_offsetof in the save/load code.

Many of the member variables that are used in save/load are inside types
that are not standard layout types. Using pointer arithmetics to determine
addresses of members inside types that are not standard layout is generally
undefined behaviour. If we'd use C++17, it is conditionally supported, which means
each compiler may or may not support it. And even then using it for individual
array elements is syntactically not supported the the standard offsetof function.

Unfortunately, the trickery employed for saving linkgraph settings causes quite some
clutter in the settings ini files.

1 files changed, 32 insertions, 12 deletions

diff --git a/src/table/settings.ini b/src/table/settings.ini
index eebb23f7e..2e085058f 100644
--- a/src/table/settings.ini
+++ b/src/table/settings.ini
@@ -62,18 +62,18 @@ const SettingDesc _settings[] = {
 [post-amble]
 };
 [templates]
-SDTG_BOOL  =  SDTG_BOOL($name,              $flags, $guiflags, $var, $def,                        $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDTG_VAR   =   SDTG_VAR($name,       $type, $flags, $guiflags, $var, $def, $min, $max, $interval, $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDTG_OMANY = SDTG_OMANY($name,       $type, $flags, $guiflags, $var, $def,       $max, $full,     $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDTC_BOOL  =  SDTC_BOOL(       $var,        $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDTC_LIST  =  SDTC_LIST(       $var, $type, $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDTC_OMANY = SDTC_OMANY(       $var, $type, $flags, $guiflags, $def,             $max, $full,     $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDTC_STR   =   SDTC_STR(       $var, $type, $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDTC_VAR   =   SDTC_VAR(       $var, $type, $flags, $guiflags, $def,       $min, $max, $interval, $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDT_BOOL   =   SDT_BOOL($base, $var,        $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDT_OMANY  =  SDT_OMANY($base, $var, $type, $flags, $guiflags, $def,             $max, $full,     $str, $strhelp, $strval, $proc, $from, $to, $load, $cat),
-SDT_STR    =    SDT_STR($base, $var, $type, $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat),
-SDT_VAR    =    SDT_VAR($base, $var, $type, $flags, $guiflags, $def,       $min, $max, $interval, $str, $strhelp, $strval, $proc, $from, $to,        $cat),
+SDTG_BOOL  =  SDTG_BOOL($name,              $flags, $guiflags, $var, $def,                        $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDTG_VAR   =   SDTG_VAR($name,       $type, $flags, $guiflags, $var, $def, $min, $max, $interval, $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDTG_OMANY = SDTG_OMANY($name,       $type, $flags, $guiflags, $var, $def,       $max, $full,     $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDTC_BOOL  =  SDTC_BOOL(       $var,        $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDTC_LIST  =  SDTC_LIST(       $var, $type, $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDTC_OMANY = SDTC_OMANY(       $var, $type, $flags, $guiflags, $def,             $max, $full,     $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDTC_STR   =   SDTC_STR(       $var, $type, $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDTC_VAR   =   SDTC_VAR(       $var, $type, $flags, $guiflags, $def,       $min, $max, $interval, $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDT_BOOL   =   SDT_BOOL($base, $var,        $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDT_OMANY  =  SDT_OMANY($base, $var, $type, $flags, $guiflags, $def,             $max, $full,     $str, $strhelp, $strval, $proc, $from, $to, $load, $cat, $extra),
+SDT_STR    =    SDT_STR($base, $var, $type, $flags, $guiflags, $def,                              $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
+SDT_VAR    =    SDT_VAR($base, $var, $type, $flags, $guiflags, $def,       $min, $max, $interval, $str, $strhelp, $strval, $proc, $from, $to,        $cat, $extra),
 SDT_NULL   =   SDT_NULL($length, $from, $to),
 SDT_END    = SDT_END()
 
@@ -89,6 +89,7 @@ load     = nullptr
 from     = SL_MIN_VERSION
 to       = SL_MAX_VERSION
 cat      = SC_ADVANCED
+extra    = 0
 
 
 
@@ -644,6 +645,7 @@ interval = 2
 str      = STR_CONFIG_SETTING_LINKGRAPH_INTERVAL
 strval   = STR_JUST_COMMA
 strhelp  = STR_CONFIG_SETTING_LINKGRAPH_INTERVAL_HELPTEXT
+extra    = offsetof(LinkGraphSettings, recalc_interval)
 
 [SDT_VAR]
 base     = GameSettings
@@ -657,6 +659,8 @@ interval = 1
 str      = STR_CONFIG_SETTING_LINKGRAPH_TIME
 strval   = STR_JUST_COMMA
 strhelp  = STR_CONFIG_SETTING_LINKGRAPH_TIME_HELPTEXT
+extra    = offsetof(LinkGraphSettings, recalc_time)
+
 
 [SDT_VAR]
 base     = GameSettings
@@ -671,6 +675,8 @@ interval = 1
 str      = STR_CONFIG_SETTING_DISTRIBUTION_PAX
 strval   = STR_CONFIG_SETTING_DISTRIBUTION_MANUAL
 strhelp  = STR_CONFIG_SETTING_DISTRIBUTION_PAX_HELPTEXT
+extra    = offsetof(LinkGraphSettings, distribution_pax)
+
 
 [SDT_VAR]
 base     = GameSettings
@@ -685,6 +691,8 @@ interval = 1
 str      = STR_CONFIG_SETTING_DISTRIBUTION_MAIL
 strval   = STR_CONFIG_SETTING_DISTRIBUTION_MANUAL
 strhelp  = STR_CONFIG_SETTING_DISTRIBUTION_MAIL_HELPTEXT
+extra    = offsetof(LinkGraphSettings, distribution_mail)
+
 
 [SDT_VAR]
 base     = GameSettings
@@ -699,6 +707,8 @@ interval = 1
 str      = STR_CONFIG_SETTING_DISTRIBUTION_ARMOURED
 strval   = STR_CONFIG_SETTING_DISTRIBUTION_MANUAL
 strhelp  = STR_CONFIG_SETTING_DISTRIBUTION_ARMOURED_HELPTEXT
+extra    = offsetof(LinkGraphSettings, distribution_armoured)
+
 
 [SDT_VAR]
 base     = GameSettings
@@ -713,6 +723,8 @@ interval = 1
 str      = STR_CONFIG_SETTING_DISTRIBUTION_DEFAULT
 strval   = STR_CONFIG_SETTING_DISTRIBUTION_MANUAL
 strhelp  = STR_CONFIG_SETTING_DISTRIBUTION_DEFAULT_HELPTEXT
+extra    = offsetof(LinkGraphSettings, distribution_default)
+
 
 [SDT_VAR]
 base     = GameSettings
@@ -726,6 +738,8 @@ interval = 1
 str      = STR_CONFIG_SETTING_LINKGRAPH_ACCURACY
 strval   = STR_JUST_COMMA
 strhelp  = STR_CONFIG_SETTING_LINKGRAPH_ACCURACY_HELPTEXT
+extra    = offsetof(LinkGraphSettings, accuracy)
+
 
 [SDT_VAR]
 base     = GameSettings
@@ -739,6 +753,8 @@ interval = 5
 str      = STR_CONFIG_SETTING_DEMAND_DISTANCE
 strval   = STR_CONFIG_SETTING_PERCENTAGE
 strhelp  = STR_CONFIG_SETTING_DEMAND_DISTANCE_HELPTEXT
+extra    = offsetof(LinkGraphSettings, demand_distance)
+
 
 [SDT_VAR]
 base     = GameSettings
@@ -752,6 +768,8 @@ interval = 5
 str      = STR_CONFIG_SETTING_DEMAND_SIZE
 strval   = STR_CONFIG_SETTING_PERCENTAGE
 strhelp  = STR_CONFIG_SETTING_DEMAND_SIZE_HELPTEXT
+extra    = offsetof(LinkGraphSettings, demand_size)
+
 
 [SDT_VAR]
 base     = GameSettings
@@ -765,6 +783,8 @@ interval = 5
 str      = STR_CONFIG_SETTING_SHORT_PATH_SATURATION
 strval   = STR_CONFIG_SETTING_PERCENTAGE
 strhelp  = STR_CONFIG_SETTING_SHORT_PATH_SATURATION_HELPTEXT
+extra    = offsetof(LinkGraphSettings, short_path_saturation)
+
 
 ; Vehicles