rust/src/librustc/lint/mod.rs
Niko Matsakis 096a28607f librustc: Make Copy opt-in.
This change makes the compiler no longer infer whether types (structures
and enumerations) implement the `Copy` trait (and thus are implicitly
copyable). Rather, you must implement `Copy` yourself via `impl Copy for
MyType {}`.

A new warning has been added, `missing_copy_implementations`, to warn
you if a non-generic public type has been added that could have
implemented `Copy` but didn't.

For convenience, you may *temporarily* opt out of this behavior by using
`#![feature(opt_out_copy)]`. Note though that this feature gate will never be
accepted and will be removed by the time that 1.0 is released, so you should
transition your code away from using it.

This breaks code like:

    #[deriving(Show)]
    struct Point2D {
        x: int,
        y: int,
    }

    fn main() {
        let mypoint = Point2D {
            x: 1,
            y: 1,
        };
        let otherpoint = mypoint;
        println!("{}{}", mypoint, otherpoint);
    }

Change this code to:

    #[deriving(Show)]
    struct Point2D {
        x: int,
        y: int,
    }

    impl Copy for Point2D {}

    fn main() {
        let mypoint = Point2D {
            x: 1,
            y: 1,
        };
        let otherpoint = mypoint;
        println!("{}{}", mypoint, otherpoint);
    }

This is the backwards-incompatible part of #13231.

Part of RFC #3.

[breaking-change]
2014-12-08 13:47:44 -05:00

267 lines
9.2 KiB
Rust

// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Lints, aka compiler warnings.
//!
//! A 'lint' check is a kind of miscellaneous constraint that a user _might_
//! want to enforce, but might reasonably want to permit as well, on a
//! module-by-module basis. They contrast with static constraints enforced by
//! other phases of the compiler, which are generally required to hold in order
//! to compile the program at all.
//!
//! Most lints can be written as `LintPass` instances. These run just before
//! translation to LLVM bytecode. The `LintPass`es built into rustc are defined
//! within `builtin.rs`, which has further comments on how to add such a lint.
//! rustc can also load user-defined lint plugins via the plugin mechanism.
//!
//! Some of rustc's lints are defined elsewhere in the compiler and work by
//! calling `add_lint()` on the overall `Session` object. This works when
//! it happens before the main lint pass, which emits the lints stored by
//! `add_lint()`. To emit lints after the main lint pass (from trans, for
//! example) requires more effort. See `emit_lint` and `GatherNodeLevels`
//! in `context.rs`.
#![macro_escape]
pub use self::Level::*;
pub use self::LintSource::*;
use std::hash;
use std::ascii::AsciiExt;
use syntax::codemap::Span;
use syntax::visit::FnKind;
use syntax::ast;
pub use lint::context::{Context, LintStore, raw_emit_lint, check_crate, gather_attrs};
/// Specification of a single lint.
pub struct Lint {
/// A string identifier for the lint.
///
/// This identifies the lint in attributes and in command-line arguments.
/// In those contexts it is always lowercase, but this field is compared
/// in a way which is case-insensitive for ASCII characters. This allows
/// `declare_lint!()` invocations to follow the convention of upper-case
/// statics without repeating the name.
///
/// The name is written with underscores, e.g. "unused_imports".
/// On the command line, underscores become dashes.
pub name: &'static str,
/// Default level for the lint.
pub default_level: Level,
/// Description of the lint or the issue it detects.
///
/// e.g. "imports that are never used"
pub desc: &'static str,
}
impl Copy for Lint {}
impl Lint {
/// Get the lint's name, with ASCII letters converted to lowercase.
pub fn name_lower(&self) -> String {
self.name.to_ascii_lower()
}
}
/// Build a `Lint` initializer.
#[macro_export]
macro_rules! lint_initializer (
($name:ident, $level:ident, $desc:expr) => (
::rustc::lint::Lint {
name: stringify!($name),
default_level: ::rustc::lint::$level,
desc: $desc,
}
)
)
/// Declare a static item of type `&'static Lint`.
#[macro_export]
macro_rules! declare_lint (
// FIXME(#14660): deduplicate
(pub $name:ident, $level:ident, $desc:expr) => (
pub static $name: &'static ::rustc::lint::Lint
= &lint_initializer!($name, $level, $desc);
);
($name:ident, $level:ident, $desc:expr) => (
static $name: &'static ::rustc::lint::Lint
= &lint_initializer!($name, $level, $desc);
);
)
/// Declare a static `LintArray` and return it as an expression.
#[macro_export]
macro_rules! lint_array ( ($( $lint:expr ),*) => (
{
#[allow(non_upper_case_globals)]
static array: LintArray = &[ $( &$lint ),* ];
array
}
))
pub type LintArray = &'static [&'static &'static Lint];
/// Trait for types providing lint checks.
///
/// Each `check` method checks a single syntax node, and should not
/// invoke methods recursively (unlike `Visitor`). By default they
/// do nothing.
//
// FIXME: eliminate the duplication with `Visitor`. But this also
// contains a few lint-specific methods with no equivalent in `Visitor`.
pub trait LintPass {
/// Get descriptions of the lints this `LintPass` object can emit.
///
/// NB: there is no enforcement that the object only emits lints it registered.
/// And some `rustc` internal `LintPass`es register lints to be emitted by other
/// parts of the compiler. If you want enforced access restrictions for your
/// `Lint`, make it a private `static` item in its own module.
fn get_lints(&self) -> LintArray;
fn check_crate(&mut self, _: &Context, _: &ast::Crate) { }
fn check_ident(&mut self, _: &Context, _: Span, _: ast::Ident) { }
fn check_mod(&mut self, _: &Context, _: &ast::Mod, _: Span, _: ast::NodeId) { }
fn check_view_item(&mut self, _: &Context, _: &ast::ViewItem) { }
fn check_foreign_item(&mut self, _: &Context, _: &ast::ForeignItem) { }
fn check_item(&mut self, _: &Context, _: &ast::Item) { }
fn check_local(&mut self, _: &Context, _: &ast::Local) { }
fn check_block(&mut self, _: &Context, _: &ast::Block) { }
fn check_stmt(&mut self, _: &Context, _: &ast::Stmt) { }
fn check_arm(&mut self, _: &Context, _: &ast::Arm) { }
fn check_pat(&mut self, _: &Context, _: &ast::Pat) { }
fn check_decl(&mut self, _: &Context, _: &ast::Decl) { }
fn check_expr(&mut self, _: &Context, _: &ast::Expr) { }
fn check_expr_post(&mut self, _: &Context, _: &ast::Expr) { }
fn check_ty(&mut self, _: &Context, _: &ast::Ty) { }
fn check_generics(&mut self, _: &Context, _: &ast::Generics) { }
fn check_fn(&mut self, _: &Context,
_: FnKind, _: &ast::FnDecl, _: &ast::Block, _: Span, _: ast::NodeId) { }
fn check_ty_method(&mut self, _: &Context, _: &ast::TypeMethod) { }
fn check_trait_method(&mut self, _: &Context, _: &ast::TraitItem) { }
fn check_struct_def(&mut self, _: &Context,
_: &ast::StructDef, _: ast::Ident, _: &ast::Generics, _: ast::NodeId) { }
fn check_struct_def_post(&mut self, _: &Context,
_: &ast::StructDef, _: ast::Ident, _: &ast::Generics, _: ast::NodeId) { }
fn check_struct_field(&mut self, _: &Context, _: &ast::StructField) { }
fn check_variant(&mut self, _: &Context, _: &ast::Variant, _: &ast::Generics) { }
fn check_variant_post(&mut self, _: &Context, _: &ast::Variant, _: &ast::Generics) { }
fn check_opt_lifetime_ref(&mut self, _: &Context, _: Span, _: &Option<ast::Lifetime>) { }
fn check_lifetime_ref(&mut self, _: &Context, _: &ast::Lifetime) { }
fn check_lifetime_def(&mut self, _: &Context, _: &ast::LifetimeDef) { }
fn check_explicit_self(&mut self, _: &Context, _: &ast::ExplicitSelf) { }
fn check_mac(&mut self, _: &Context, _: &ast::Mac) { }
fn check_path(&mut self, _: &Context, _: &ast::Path, _: ast::NodeId) { }
fn check_attribute(&mut self, _: &Context, _: &ast::Attribute) { }
/// Called when entering a syntax node that can have lint attributes such
/// as `#[allow(...)]`. Called with *all* the attributes of that node.
fn enter_lint_attrs(&mut self, _: &Context, _: &[ast::Attribute]) { }
/// Counterpart to `enter_lint_attrs`.
fn exit_lint_attrs(&mut self, _: &Context, _: &[ast::Attribute]) { }
}
/// A lint pass boxed up as a trait object.
pub type LintPassObject = Box<LintPass + 'static>;
/// Identifies a lint known to the compiler.
#[deriving(Clone)]
pub struct LintId {
// Identity is based on pointer equality of this field.
lint: &'static Lint,
}
impl Copy for LintId {}
impl PartialEq for LintId {
fn eq(&self, other: &LintId) -> bool {
(self.lint as *const Lint) == (other.lint as *const Lint)
}
}
impl Eq for LintId { }
impl<S: hash::Writer> hash::Hash<S> for LintId {
fn hash(&self, state: &mut S) {
let ptr = self.lint as *const Lint;
ptr.hash(state);
}
}
impl LintId {
/// Get the `LintId` for a `Lint`.
pub fn of(lint: &'static Lint) -> LintId {
LintId {
lint: lint,
}
}
/// Get the name of the lint.
pub fn as_str(&self) -> String {
self.lint.name_lower()
}
}
/// Setting for how to handle a lint.
#[deriving(Clone, PartialEq, PartialOrd, Eq, Ord)]
pub enum Level {
Allow, Warn, Deny, Forbid
}
impl Copy for Level {}
impl Level {
/// Convert a level to a lower-case string.
pub fn as_str(self) -> &'static str {
match self {
Allow => "allow",
Warn => "warn",
Deny => "deny",
Forbid => "forbid",
}
}
/// Convert a lower-case string to a level.
pub fn from_str(x: &str) -> Option<Level> {
match x {
"allow" => Some(Allow),
"warn" => Some(Warn),
"deny" => Some(Deny),
"forbid" => Some(Forbid),
_ => None,
}
}
}
/// How a lint level was set.
#[deriving(Clone, PartialEq, Eq)]
pub enum LintSource {
/// Lint is at the default level as declared
/// in rustc or a plugin.
Default,
/// Lint level was set by an attribute.
Node(Span),
/// Lint level was set by a command-line flag.
CommandLine,
}
impl Copy for LintSource {}
pub type LevelSource = (Level, LintSource);
pub mod builtin;
mod context;