On 02/10/2019 22:23, Luc Van Oostenryck wrote:
> As an extension, allow conditional expressions (?:) with one
> side of type 'void' and consider the result to also be void.
>
> The warning can be reinstated with the flag '-Wcond-void'.
Hmm, I think this is a backward step ...
>
> Note: I only see a single occurrence of this in the kernel.
... and the fact that such code exists in the kernel is, er,
somewhat disappointing ... :(
But, hey, what do I know.
For a typo in the documentation, (see below)
>
> Suggested-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
> ---
> evaluate.c | 7 +++++++
> lib.c | 2 ++
> lib.h | 1 +
> sparse.1 | 7 +++++++
> validation/cond-err-expand.c | 2 +-
> 5 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/evaluate.c b/evaluate.c
> index 919c944cf..fb1a0548d 100644
> --- a/evaluate.c
> +++ b/evaluate.c
> @@ -1205,6 +1205,13 @@ static struct symbol *evaluate_conditional_expression(struct expression *expr)
> goto out;
> }
>
> + // extension: allow the result be void is one side is void
> + if (ltype == &void_ctype || rtype == &void_ctype) {
> + ctype = &void_ctype;
> + if (!Wcond_void)
> + goto out;
> + }
> +
> if ((lclass | rclass) & TYPE_PTR) {
> int is_null1 = is_null_pointer_constant(*cond);
> int is_null2 = is_null_pointer_constant(expr->cond_false);
> diff --git a/lib.c b/lib.c
> index 83e6a1e1b..c16d87778 100644
> --- a/lib.c
> +++ b/lib.c
> @@ -257,6 +257,7 @@ int Wbitwise_pointer = 0;
> int Wcast_from_as = 0;
> int Wcast_to_as = 0;
> int Wcast_truncate = 1;
> +int Wcond_void = 0;
> int Wconstant_suffix = 0;
> int Wconstexpr_not_const = 0;
> int Wcontext = 1;
> @@ -639,6 +640,7 @@ static const struct flag warnings[] = {
> { "cast-from-as", &Wcast_from_as },
> { "cast-to-as", &Wcast_to_as },
> { "cast-truncate", &Wcast_truncate },
> + { "cond-void", &Wcond_void },
> { "constant-suffix", &Wconstant_suffix },
> { "constexpr-not-const", &Wconstexpr_not_const},
> { "context", &Wcontext },
> diff --git a/lib.h b/lib.h
> index 697c977a1..2549c8872 100644
> --- a/lib.h
> +++ b/lib.h
> @@ -145,6 +145,7 @@ extern int Wbitwise_pointer;
> extern int Wcast_from_as;
> extern int Wcast_to_as;
> extern int Wcast_truncate;
> +extern int Wcond_void;
> extern int Wconstant_suffix;
> extern int Wconstexpr_not_const;
> extern int Wcontext;
> diff --git a/sparse.1 b/sparse.1
> index beb484423..71ac0c646 100644
> --- a/sparse.1
> +++ b/sparse.1
> @@ -117,6 +117,13 @@ Sparse issues these warnings by default. To turn them off, use
> \fB\-Wno\-cast\-truncate\fR.
> .
> .TP
> +.B \-Wconditional\-void
The warning, as implemented, is -Wcond-void.
ATB,
Ramsay Jones
> +Warn if one side of a conditional expression (\fB? :\fR) is of type
> +void and the other one not.
> +As an extension, Sparse consider the result of such expressions as also
> +having the type void.
> +.
> +.TP
> .B \-Wconstant\-suffix
> Warn if an integer constant is larger than the maximum representable value
> of the type indicated by its type suffix (if any). For example, on a
> diff --git a/validation/cond-err-expand.c b/validation/cond-err-expand.c
> index b52624bc9..714cb23eb 100644
> --- a/validation/cond-err-expand.c
> +++ b/validation/cond-err-expand.c
> @@ -15,7 +15,7 @@ void bar(void)
>
> /*
> * check-name: cond-err-expand.c
> - * check-command: test-linearize -Wno-decl $file
> + * check-command: test-linearize -Wcond-void -Wno-decl $file
> *
> * check-error-start
> cond-err-expand.c:8:11: error: incompatible types in conditional expression (different base types):
>
