[cairo] compiler warnings in cairo_wideint.h/c
Carl Worth
cworth at cworth.org
Wed Oct 13 13:59:52 PDT 2004
On Wed, 13 Oct 2004 09:10:40 -0700, Keith Packard wrote:
> Around 8 o'clock on Oct 13, "Andreas Tobler" wrote:
>
> > /* Type qualifiers on a function return type are
> > normally permitted by the standard but have no
> > effect.
> > */
>
> Hmm. The effect I was trying to induce was to teach the compiler that
> given fixed arguments, these functions always return the same result
> (i.e., they are "pure" functions). I thought that's what the 'const'
> qualifier on the return value did.
It would be nice to indicate that kind of information to the compiler.
But, according to C99, "const" is a "type qualifier" and as such
specifies properties that are "meaningful only for expressions that are
lvalues" §6.7.3 (3). Even more significant to the current code is:
"If the specification of a function type includes any type
qualifiers, the behavior is undefined." §6.7.3 (8)
Bummer.
-Carl
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