Enum Standard 

pub enum Standard {
    C89,
    C99,
    C11,
    C17,
    C23,
}

Which revision of the C standard to accept.

The variants are ordered, so a feature is gated by comparing: a construct C11 introduced is accepted when standard >= Standard::C11. C17 is C11 with a different __STDC_VERSION__ and adds nothing else.

Variants

C89

ISO/IEC 9899:1990, the standard everyone still calls C89.

C90 is the ISO republication of ANSI X3.159-1989 with no technical change, so c89! and c90! are one entry point under two names.

C99

ISO/IEC 9899:1999.

C11

ISO/IEC 9899:2011.

C17

ISO/IEC 9899:2018.

C23

ISO/IEC 9899:2024.

Implementations

impl Standard

pub fn stdc_version(self) -> Option<&'static str>

The value of __STDC_VERSION__ for this revision, or None where the revision has none.

C89 as published had no __STDC_VERSION__ at all — Amendment 1 added it in 1995 — so c89! and gnu89! leave the macro undefined, which is what gcc -std=c89 does and what a program testing #ifdef __STDC_VERSION__ is looking for. __STDC__ is still 1.

impl Standard

pub fn as_str(self) -> &'static str

The name used in diagnostics.

pub fn macro_name(self) -> &'static str

The macro that selects this standard, as a diagnostic names it.

pub fn macro_name_in(self, dialect: Dialect) -> &'static str

The macro that selects this standard in dialect.

pub fn macro_names_in(self, dialect: Dialect) -> &'static [&'static str]

Every name the macro that selects this standard in dialect may be written with, without the !.

Two of them only for C89, which has two names and one entry point; the point of the list is that the search for an invocation in the crate’s sources knows what to look for, and c90! { … } has to be found as readily as c89! { … }.

pub fn include_macro_names_in(self, dialect: Dialect) -> &'static [&'static str]

The same for the include_…! family, which is one entry point per name of Standard::macro_names_in.

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

The message a feature from a newer revision gets in this one.

what is the subject, already quoted where it names a token: standard.requires("'_Static_assert'", Standard::C11) reads '_Static_assert' requires C11 or later (this block is c99!). Saying which macro the block is written with is the point — the fix is to change the macro, and nothing in the C says which one it is.

Trait Implementations

impl Clone for Standard

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 Standard

impl Debug for Standard

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

Formats the value using the given formatter.

impl Default for Standard

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Standard

impl Ord for Standard

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for Standard

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for Standard

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for Standard