Re: [patch] Extend former fold_widened_comparison to all integral types

[Eric Botcazou <ebotcazou at adacore dot com>]

> I think excluding enums had sth to do with C++ -f[no-]strict-enums
> (whatever is the default).  Just tried to figure where the check
> came from ... both calls are keyed on INTEGER_TYPE...

Here's the relevant block of code from the C++ front-end:

      /* The middle-end currently assumes that types with TYPE_PRECISION
	 narrower than their underlying type are suitably zero or sign
	 extended to fill their mode.  Similarly, it assumes that the front
	 end assures that a value of a particular type must be within
	 TYPE_MIN_VALUE and TYPE_MAX_VALUE.

	 We used to set these fields based on bmin and bmax, but that led
	 to invalid assumptions like optimizing away bounds checking.  So
	 now we just set the TYPE_PRECISION, TYPE_MIN_VALUE, and
	 TYPE_MAX_VALUE to the values for the mode above and only restrict
	 the ENUM_UNDERLYING_TYPE for the benefit of diagnostics.  */
      ENUM_UNDERLYING_TYPE (enumtype)
	= build_distinct_type_copy (underlying_type);
      TYPE_PRECISION (ENUM_UNDERLYING_TYPE (enumtype)) = precision;
      set_min_and_max_values_for_integral_type
        (ENUM_UNDERLYING_TYPE (enumtype), precision, sgn);

      /* If -fstrict-enums, still constrain TYPE_MIN/MAX_VALUE.  */
      if (flag_strict_enums)
	set_min_and_max_values_for_integral_type (enumtype, precision, sgn);

So the compiler should still not optimize if -fno-strict-enums AFAICS.

-- 
Eric Botcazou