ppci-cc: handling of big constants with L specifier

[tstreiff]

In x86_64, ints are 32bit and longs are 64bit.

long l1 = 9223372036854775807; // LONG_MAX
long l2 = -9223372036854775808; // LONG_MIN
long l3 = -9223372036854775808L; // same value but...
^ Integer value too big for type (9223372036854775807)

The value is OK for an "int" constant (with no type specifier) but is too big for a "long" constant (L type specifier)

[tstreiff]

This is checked in semantics.py/on_number()
The subtle point is that integer constants are always positive, so this function does not know if a sign has been found just before.
And the maximum absolute value is not the same for negative et positive values.

• case l2 works because since there are no type specifiers, the compiler chooses the smallest integer type able to cope with the (positive) value. This requires unsigned 64bit integer (unsigned long for x86_64)
• case l3 does not work because the type "signed long" is deduced from the L specifier.

According to the C standard, the "L" specifiers implies "long int" or "long long int" (the 1st of the two large enough to hold the value)
A possible fix for integers would be:

1. We let the compiler find the shortest type suitable for the value
2. If a specifier is given, we "upgrade" the type found in 1)
   I am not sure step 2) is really necessary because type of integer constants is rarely used (their type is adjusted on demand)
   An exception is passing a constant to a "old-style" (ie K&R) function: specifying the type of a constant in a function call can help the compiler choose how to put it on the stack (on an architecture where ints are 16bit and longs are 32bit, passing 0 requires one level of stack, whereas passing 0L requires two)