Struct Feature 

pub struct Feature {
    pub name: &'static str,
    pub kind: Kind,
    pub gcc_version: &'static str,
    pub status: Status,
    pub signature: &'static str,
    pub library: &'static str,
    pub answer: Answer,
    pub value: u32,
    pub used_by: &'static [&'static str],
    pub tests: &'static [&'static str],
    pub notes: &'static str,
}

One row of the matrix.

Fields

name: &'static str

The spelling asked about, with no __ armour on it.

kind: Kind

Which operator answers for it.

gcc_version: &'static str

The GCC release that introduced it.

status: Status

How far along it is.

signature: &'static str

The type a builtin has, written as a C prototype without the name, or empty.

Empty for everything that is not a builtin, and for a builtin whose type depends on what it is handed: __builtin_constant_p takes anything, __builtin_add_overflow takes three types that have to agree, and the atomics are a family rather than a function. Those are decided where the arguments are, and a fixed type here would be a worse answer than none.

It is a string rather than a structure because size_t is a different type on two targets and this table has no target. The compiler reads it once per builtin it is asked for. The set of words it may use is fixed and build.rs checks it, so a typo fails this crate’s build rather than the compile of whoever first calls the builtin.

library: &'static str

The library function this builtin is, for the family where that is the whole answer.

Empty for everything else. GCC’s __builtin_abort is a call to abort, its __builtin_strlen a call to strlen, and the prefix is there so that a program can reach the function the C library promises even where its own name has been taken by a macro or by a definition of its own. GCC folds some of these when the arguments allow it, and folding is an optimization on top: the call is the meaning, and a compiler that only ever emits the call is right and slow rather than wrong.

The name is written out rather than worked out by stripping the prefix, because the two are the same for every row here and need not be for the next one, and a table that says what it means is worth more than one that saves thirty words.

answer: Answer

What to do when it is met and is not implemented.

value: u32

What __has_c_attribute answers with, which the standard fixes per attribute. One for every other kind, where the operators answer one or nothing.

used_by: &'static [&'static str]

Projects known to need it, from the corpus in spec/15-testing.md.

tests: &'static [&'static str]

The tests that prove the status, named as crate::test or as a file path.

notes: &'static str

Anything a reader needs that the fields above do not say.

Trait Implementations

impl Clone for Feature

fn clone(&self) -> Feature

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Feature

impl Debug for Feature

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

Formats the value using the given formatter.

impl Eq for Feature

impl PartialEq for Feature

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Feature