Re: INT_MIN and compiler diagnostic

On 28 Feb, 13:20, Chris Dollin <chris.dol...@xxxxxx> wrote:
bytebro wrote:
On 28 Feb, 12:34, pete <pfil...@xxxxxxxxxxxxxx> wrote:

If INT_MAX equals 2147483647,
the the type of 2147483648 can't be type int, can it?

Erm... it doesn't say "2147483648", it says "-2147483648", which is
exactly equal to INT_MIN, and is therefore a valid int value. The
warning is therefore misleading, no?

No.

`-2147483648` isn't a literal constant. It's an expression, the
negation of `2147483648`.

Wow. I've been mucking around with C for about 20 years now, and
that's the first time I've come across that!

The thing is, in the OP's code lines 7 and 8, it says:

7 int y = -2147483648;
8 int x = INT_MIN;

which are _completely_ equivalent (INT_MIN is _defined_ as
-2147483648), and yet line 7 generates the warning:

/tmp/x.c:7: warning: this decimal constant is unsigned only in ISO
C90

on his system, and the warning:

x.c:7: warning: decimal constant is so large that it is unsigned

on my system, but line 8 generates no warning at all for either of us.

.

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