Matthias Klose wrote:
>
> The -Wconversion option to gcc is documented as doing two things:
>
> ------------------------------------------------------------------------
> `-Wconversion'
> Warn if a prototype causes a type conversion that is different
> from what would happen to the same argument in the absence of a
> prototype. This includes conversions of fixed point to floating
> and vice versa, and conversions changing the width or signedness
> of a fixed point argument except when the same as the default
> promotion.
>
> Also, warn if a negative integer constant expression is implicitly
> converted to an unsigned type. For example, warn about the
> assignment `x = -1' if `x' is unsigned. But do not warn about
> explicit casts like `(unsigned) -1'.
> ------------------------------------------------------------------------
>
> It'd be nice if these two behaviors were two controlled via two
> separate flags. The second behavior would have caught a bug I've been
> hunting for hours, while the first behavior is very undesirable to me
> (and useless since I also compile with -Wstrict-prototypes).
I remember having been annoyed by -Wconversion its behaviour, too. Maybe
this patch will do what you want?
Segher
2002-12-28 Segher Boessenkool <[EMAIL PROTECTED]>
* c-typeck.c (convert_arguments): Don't warn about arguments
passed as `float' unless -Wtraditional given. Add warning
to -Wconversion for passing floating point arguments in smaller
precision. Add warning to -Wtraditional for passing integers with
different width due to prototype.
* doc/invoke.texi (Warning Options): Document this. Clarify.
* doc/trouble.texi (Protoize Caveats): Ditto.
*** ../../gcc-clean/gcc/c-typeck.c Fri Dec 27 03:21:39 2002
--- ./c-typeck.c Sat Dec 28 16:44:19 2002
*************** convert_arguments (typelist, values, nam
*** 1645,1657 ****
{
/* Warn if any argument is passed as `float',
since without a prototype it would be `double'. */
! if (formal_prec == TYPE_PRECISION (float_type_node))
warn_for_assignment ("%s as `float' rather than
`double' due to prototype", (char *) 0, name, parmnum + 1);
}
/* Detect integer changing in width or signedness.
! These warnings are only activated with
-Wconversion, not with -Wtraditional. */
! else if (warn_conversion && INTEGRAL_TYPE_P (type)
&& INTEGRAL_TYPE_P (TREE_TYPE (val)))
{
tree would_have_been = default_conversion (val);
--- 1645,1659 ----
{
/* Warn if any argument is passed as `float',
since without a prototype it would be `double'. */
! if (warn_traditional && formal_prec == TYPE_PRECISION
(float_type_node))
warn_for_assignment ("%s as `float' rather than
`double' due to prototype", (char *) 0, name, parmnum + 1);
+ else if (warn_conversion && TYPE_PRECISION (TREE_TYPE
(val)) < formal_prec)
+ warn_for_assignment ("%s with smaller precision due to
prototype", (char *) 0, name, parmnum + 1);
}
/* Detect integer changing in width or signedness.
! The warning for signedness is only activated with
-Wconversion, not with -Wtraditional. */
! else if (INTEGRAL_TYPE_P (type)
&& INTEGRAL_TYPE_P (TREE_TYPE (val)))
{
tree would_have_been = default_conversion (val);
*************** convert_arguments (typelist, values, nam
*** 1666,1671 ****
--- 1668,1675 ----
else if (formal_prec != TYPE_PRECISION (type1))
warn_for_assignment ("%s with different width due to
prototype", (char *) 0, name, parmnum + 1);
else if (TREE_UNSIGNED (type) == TREE_UNSIGNED (type1))
+ ;
+ else if (!warn_conversion)
;
/* Don't complain if the formal parameter type
is an enum, because we can't tell now whether
*** ../../gcc-clean/gcc/doc/invoke.texi Fri Dec 27 03:21:40 2002
--- ./doc/invoke.texi Sat Dec 28 16:27:54 2002
*************** traditional C case.
*** 2600,2610 ****
@item
Conversions by prototypes between fixed/floating point values and vice
! versa. The absence of these prototypes when compiling with traditional
C would cause serious problems. This is a subset of the possible
conversion warnings, for the full set use @option{-Wconversion}.
@item
Use of ISO C style function definitions. This warning intentionally is
@emph{not} issued for prototype declarations or variadic functions
because these ISO C features will appear in your code when using
--- 2600,2616 ----
@item
Conversions by prototypes between fixed/floating point values and vice
! versa, and conversion by prototypes between different width types when
! not equal to the default promotions.
! The absence of these prototypes when compiling with traditional
C would cause serious problems. This is a subset of the possible
conversion warnings, for the full set use @option{-Wconversion}.
@item
+ Use of @code{float} in prototypes. Traditional C would pass such
+ parameters as @code{double}, while ISO C does not.
+
+ @item
Use of ISO C style function definitions. This warning intentionally is
@emph{not} issued for prototype declarations or variadic functions
because these ISO C features will appear in your code when using
*************** this is why we did not make @option{-Wal
*** 2671,2681 ****
@item -Wconversion
@opindex Wconversion
! Warn if a prototype causes a type conversion that is different from what
! would happen to the same argument in the absence of a prototype. This
! includes conversions of fixed point to floating and vice versa, and
! conversions changing the width or signedness of a fixed point argument
! except when the same as the default promotion.
Also, warn if a negative integer constant expression is implicitly
converted to an unsigned type. For example, warn about the assignment
--- 2677,2687 ----
@item -Wconversion
@opindex Wconversion
! Warn if a prototype causes an implicit type conversion that is different
! from the default promotion. This includes conversions of fixed point to
! floating and vice versa, and conversions changing the width or
! signedness of a fixed point argument (except when the same as the default
! promotion).
Also, warn if a negative integer constant expression is implicitly
converted to an unsigned type. For example, warn about the assignment
*** ../../gcc-clean/gcc/doc/trouble.texi Mon Sep 16 00:48:05 2002
--- ./doc/trouble.texi Sat Dec 28 16:29:53 2002
*************** without them.
*** 1110,1117 ****
@opindex Wconversion
You can find all the places where this problem might occur by compiling
! the program with the @option{-Wconversion} option. It prints a warning
! whenever an argument is converted.
@item
Both conversion programs can be confused if there are macro calls in and
--- 1110,1117 ----
@opindex Wconversion
You can find all the places where this problem might occur by compiling
! the program with the @option{-Wtraditional -Wconversion} options. It
! prints a warning whenever an argument is converted.
@item
Both conversion programs can be confused if there are macro calls in and
