Struct Gating 

pub struct Gating {
    pub standard: Standard,
    pub dialect: Dialect,
}

The pair every pass needs to answer “may this block write that?”.

A GNU dialect answers yes to everything a later revision added, exactly as GCC’s -std=gnu99 does; the strict entry points keep the diagnostic that names the macro to write instead.

Fields

standard: Standard

The revision the block is written in.

dialect: Dialect

Whether the GNU extensions are switched on.

Implementations

impl Gating

pub fn requires(self, what: &str, needed: Standard) -> Option<String>

The message a feature from a newer revision gets here, or None when it is accepted.

pub fn implicit_int(self) -> bool

Whether a declaration with no type specifier at all means int (C89 6.5.2).

C99 removed implicit int (N635) and GCC diagnoses it in every later mode, -std=gnu99 included, so this is one of the three places where gnu89! is older than gnu99! rather than a superset of it.

pub fn implicit_function_declarations(self) -> bool

Whether a call to a function nobody declared declares extern int f(); at file scope (C89 6.3.2.2).

C99 removed the rule (N636); see Gating::implicit_int for why the GNU dialect does not bring it back.

pub fn old_style_definitions(self) -> bool

Whether an old-style (K&R) function definition may be written.

Obsolescent from C89 onwards and removed by C23 (N2432), so every entry point below c23! has it and the two C23 ones do not.

pub fn newer_keyword(self, name: &str) -> Option<String>

The gate message for name, if another entry point would have made it a keyword.

nullptr, bool and the rest are ordinary identifiers before C23 — the bundled <stdbool.h> writes #define bool _Bool — so a c11! block that uses one gets told what it would have meant. A GNU dialect says nothing about those: GCC’s gnu11 has no bool keyword either, so “use of undeclared identifier” is the honest answer there.

typeof and asm are the two the dialect decides, so their message names the entry point that has them.

Trait Implementations

impl Clone for Gating

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Gating

impl Debug for Gating

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Gating

fn default() -> Self

Returns the “default value” for a type.