settings: Fix possible undefined behavior with va_start() and bool
This fixes compilation with -Werror when using Clang 4.0 (but not 3.9) and possibly prevents undefined behavior. According to the C standard the following applies to the second parameter of the va_start() macro (subclause 7.16.1.4, paragraph 4): The parameter parmN is the identifier of the rightmost parameter in the variable parameter list in the function definition (the one just before the ...). If the parameter parmN is declared with the register storage class, with a function or array type, or with a type that is not compatible with the type that results after application of the default argument promotions, the behavior is undefined. Because bool is usually just 1 byte and therefore smaller than int (i.e. the result of default argument promotion) its use as last argument before ... might result in undefined behavior. This theoretically can also apply to enums as a compiler may use a smaller base type than int. Since Clang 3.9 (currently in use on Travis by default) a warning is issued about this, however, that version did not yet compare the actual size of the argument's type, causing warnings where they are not warranted (basically for all cases where enum types are used for the last argument). This was apparently fixed with Clang 4.0, which only warns about this use of bool with va_start(), which makes sense.
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@ -494,11 +494,12 @@ inline bool settings_value_as_bool(char *value, bool def)
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}
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METHOD(settings_t, get_bool, bool,
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private_settings_t *this, char *key, bool def, ...)
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private_settings_t *this, char *key, int def, ...)
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{
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char *value;
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va_list args;
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/* we can't use bool for def due to this call */
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va_start(args, def);
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value = find_value(this, this->top, key, args);
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va_end(args);
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@ -665,9 +666,10 @@ METHOD(settings_t, set_str, void,
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}
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METHOD(settings_t, set_bool, void,
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private_settings_t *this, char *key, bool value, ...)
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private_settings_t *this, char *key, int value, ...)
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{
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va_list args;
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/* we can't use bool for value due to this call */
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va_start(args, value);
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set_value(this, this->top, key, args, value ? "1" : "0");
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va_end(args);
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@ -173,7 +173,7 @@ struct settings_t {
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* @param ... argument list for key
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* @return value of the key
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*/
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bool (*get_bool)(settings_t *this, char *key, bool def, ...);
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bool (*get_bool)(settings_t *this, char *key, int def, ...);
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/**
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* Get an integer value.
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@ -221,7 +221,7 @@ struct settings_t {
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* @param value value to set
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* @param ... argument list for key
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*/
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void (*set_bool)(settings_t *this, char *key, bool value, ...);
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void (*set_bool)(settings_t *this, char *key, int value, ...);
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/**
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* Set an integer value.
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