On Sat, Mar 01, 2014 at 11:41:39AM +0000, John Keeping wrote:
> This stops warnings in code using socket operations with a modern glibc,
> which otherwise result in warnings of the form:
>
> warning: incorrect type in argument 2 (invalid types)
> expected union __CONST_SOCKADDR_ARG [usertype] __addr
> got struct sockaddr *<noident>
>
> Since transparent unions are only applicable to function arguments, we
> create a new function to check that the types are compatible
> specifically in this context.
>
> Signed-off-by: John Keeping <john@xxxxxxxxxxxxx>
Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
> evaluate.c | 28 +++++++++++++++++++++++++++-
> lib.c | 2 --
> lib.h | 1 -
> parse.c | 6 ++++--
> sparse.1 | 8 --------
> symbol.h | 3 ++-
> validation/transparent-union.c | 25 +++++++++++++++++++++++++
> 7 files changed, 58 insertions(+), 15 deletions(-)
> create mode 100644 validation/transparent-union.c
>
> diff --git a/evaluate.c b/evaluate.c
> index 2e6511b..f36c6c1 100644
> --- a/evaluate.c
> +++ b/evaluate.c
> @@ -1406,6 +1406,32 @@ static int compatible_assignment_types(struct expression *expr, struct symbol *t
> return 1;
> }
>
> +static int compatible_argument_type(struct expression *expr, struct symbol *target,
> + struct expression **rp, const char *where)
> +{
> + const char *typediff;
> + struct symbol *source = degenerate(*rp);
> + struct symbol *t;
> + classify_type(target, &t);
> +
> + if (t->type == SYM_UNION && t->transparent_union) {
> + struct symbol *member;
> + FOR_EACH_PTR(t->symbol_list, member) {
> + if (check_assignment_types(member, rp, &typediff))
> + return 1;
> + } END_FOR_EACH_PTR(member);
> + }
> +
> + if (check_assignment_types(target, rp, &typediff))
> + return 1;
> +
> + warning(expr->pos, "incorrect type in %s (%s)", where, typediff);
> + info(expr->pos, " expected %s", show_typename(target));
> + info(expr->pos, " got %s", show_typename(source));
> + *rp = cast_to(*rp, target);
> + return 0;
> +}
> +
> static void mark_assigned(struct expression *expr)
> {
> struct symbol *sym;
> @@ -2172,7 +2198,7 @@ static int evaluate_arguments(struct symbol *f, struct symbol *fn, struct expres
> static char where[30];
> examine_symbol_type(target);
> sprintf(where, "argument %d", i);
> - compatible_assignment_types(expr, target, p, where);
> + compatible_argument_type(expr, target, p, where);
> }
>
> i++;
> diff --git a/lib.c b/lib.c
> index bf3e91c..a52b88e 100644
> --- a/lib.c
> +++ b/lib.c
> @@ -226,7 +226,6 @@ int Wparen_string = 0;
> int Wptr_subtraction_blows = 0;
> int Wreturn_void = 0;
> int Wshadow = 0;
> -int Wtransparent_union = 0;
> int Wtypesign = 0;
> int Wundef = 0;
> int Wuninitialized = 1;
> @@ -438,7 +437,6 @@ static const struct warning {
> { "ptr-subtraction-blows", &Wptr_subtraction_blows },
> { "return-void", &Wreturn_void },
> { "shadow", &Wshadow },
> - { "transparent-union", &Wtransparent_union },
> { "typesign", &Wtypesign },
> { "undef", &Wundef },
> { "uninitialized", &Wuninitialized },
> diff --git a/lib.h b/lib.h
> index f09b338..197b549 100644
> --- a/lib.h
> +++ b/lib.h
> @@ -120,7 +120,6 @@ extern int Wparen_string;
> extern int Wptr_subtraction_blows;
> extern int Wreturn_void;
> extern int Wshadow;
> -extern int Wtransparent_union;
> extern int Wtypesign;
> extern int Wundef;
> extern int Wuninitialized;
> diff --git a/parse.c b/parse.c
> index 9cc5f65..bf62bdd 100644
> --- a/parse.c
> +++ b/parse.c
> @@ -1207,8 +1207,10 @@ static struct token *attribute_designated_init(struct token *token, struct symbo
>
> static struct token *attribute_transparent_union(struct token *token, struct symbol *attr, struct decl_state *ctx)
> {
> - if (Wtransparent_union)
> - warning(token->pos, "ignoring attribute __transparent_union__");
> + if (ctx->ctype.base_type && ctx->ctype.base_type->type == SYM_UNION)
> + ctx->ctype.base_type->transparent_union = 1;
> + else
> + warning(token->pos, "attribute __transparent_union__ applied to non-union type");
> return token;
> }
>
> diff --git a/sparse.1 b/sparse.1
> index cd6be26..6e79202 100644
> --- a/sparse.1
> +++ b/sparse.1
> @@ -297,14 +297,6 @@ Such declarations can lead to error-prone code.
> Sparse does not issue these warnings by default.
> .
> .TP
> -.B \-Wtransparent\-union
> -Warn about any declaration using the GCC extension
> -\fB__attribute__((transparent_union))\fR.
> -
> -Sparse issues these warnings by default. To turn them off, use
> -\fB\-Wno\-transparent\-union\fR.
> -.
> -.TP
> .B \-Wtypesign
> Warn when converting a pointer to an integer type into a pointer to an integer
> type with different signedness.
> diff --git a/symbol.h b/symbol.h
> index 43c165b..ccb5dcb 100644
> --- a/symbol.h
> +++ b/symbol.h
> @@ -174,7 +174,8 @@ struct symbol {
> evaluated:1,
> string:1,
> designated_init:1,
> - forced_arg:1;
> + forced_arg:1,
> + transparent_union:1;
> struct expression *array_size;
> struct ctype ctype;
> struct symbol_list *arguments;
> diff --git a/validation/transparent-union.c b/validation/transparent-union.c
> new file mode 100644
> index 0000000..149c7d9
> --- /dev/null
> +++ b/validation/transparent-union.c
> @@ -0,0 +1,25 @@
> +struct a {
> + int field;
> +};
> +struct b {
> + int field;
> +};
> +
> +typedef union {
> + struct a *a;
> + struct b *b;
> +} transparent_arg __attribute__((__transparent_union__));
> +
> +static void foo(transparent_arg arg)
> +{
> +}
> +
> +static void bar(void)
> +{
> + struct b arg = { 0 };
> + foo((struct a *) &arg);
> +}
> +
> +/*
> + * check-name: Transparent union attribute.
> + */
> --
> 1.9.0.6.g037df60.dirty
>
> --
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