580 lines
22 KiB
Rust
580 lines
22 KiB
Rust
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Feature gating
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//!
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//! This modules implements the gating necessary for preventing certain compiler
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//! features from being used by default. This module will crawl a pre-expanded
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//! AST to ensure that there are no features which are used that are not
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//! enabled.
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//!
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//! Features are enabled in programs via the crate-level attributes of
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//! `#![feature(...)]` with a comma-separated list of features.
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//!
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//! For the purpose of future feature-tracking, once code for detection of feature
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//! gate usage is added, *do not remove it again* even once the feature
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//! becomes stable.
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use self::Status::*;
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use abi::RustIntrinsic;
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use ast::NodeId;
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use ast;
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use attr;
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use attr::AttrMetaMethods;
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use codemap::{CodeMap, Span};
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use diagnostic::SpanHandler;
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use visit;
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use visit::Visitor;
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use parse::token::{self, InternedString};
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use std::slice;
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use std::ascii::AsciiExt;
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// If you change this list without updating src/doc/reference.md, @cmr will be sad
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// Don't ever remove anything from this list; set them to 'Removed'.
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// The version numbers here correspond to the version in which the current status
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// was set. This is most important for knowing when a particular feature became
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// stable (active).
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// NB: The featureck.py script parses this information directly out of the source
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// so take care when modifying it.
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static KNOWN_FEATURES: &'static [(&'static str, &'static str, Status)] = &[
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("globs", "1.0.0", Accepted),
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("macro_rules", "1.0.0", Accepted),
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("struct_variant", "1.0.0", Accepted),
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("asm", "1.0.0", Active),
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("managed_boxes", "1.0.0", Removed),
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("non_ascii_idents", "1.0.0", Active),
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("thread_local", "1.0.0", Active),
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("link_args", "1.0.0", Active),
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("phase", "1.0.0", Removed),
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("plugin_registrar", "1.0.0", Active),
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("log_syntax", "1.0.0", Active),
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("trace_macros", "1.0.0", Active),
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("concat_idents", "1.0.0", Active),
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("unsafe_destructor", "1.0.0", Active),
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("intrinsics", "1.0.0", Active),
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("lang_items", "1.0.0", Active),
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("simd", "1.0.0", Active),
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("default_type_params", "1.0.0", Accepted),
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("quote", "1.0.0", Active),
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("link_llvm_intrinsics", "1.0.0", Active),
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("linkage", "1.0.0", Active),
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("struct_inherit", "1.0.0", Removed),
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("quad_precision_float", "1.0.0", Removed),
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("rustc_diagnostic_macros", "1.0.0", Active),
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("unboxed_closures", "1.0.0", Active),
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("import_shadowing", "1.0.0", Active),
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("advanced_slice_patterns", "1.0.0", Active),
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("tuple_indexing", "1.0.0", Accepted),
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("associated_types", "1.0.0", Accepted),
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("visible_private_types", "1.0.0", Active),
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("slicing_syntax", "1.0.0", Active),
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("box_syntax", "1.0.0", Active),
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("on_unimplemented", "1.0.0", Active),
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("simd_ffi", "1.0.0", Active),
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("if_let", "1.0.0", Accepted),
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("while_let", "1.0.0", Accepted),
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("plugin", "1.0.0", Active),
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("start", "1.0.0", Active),
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("main", "1.0.0", Active),
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// A temporary feature gate used to enable parser extensions needed
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// to bootstrap fix for #5723.
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("issue_5723_bootstrap", "1.0.0", Accepted),
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// A way to temporarily opt out of opt in copy. This will *never* be accepted.
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("opt_out_copy", "1.0.0", Removed),
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// A way to temporarily opt out of the new orphan rules. This will *never* be accepted.
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("old_orphan_check", "1.0.0", Deprecated),
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// A way to temporarily opt out of the new impl rules. This will *never* be accepted.
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("old_impl_check", "1.0.0", Deprecated),
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// OIBIT specific features
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("optin_builtin_traits", "1.0.0", Active),
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// int and uint are now deprecated
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("int_uint", "1.0.0", Active),
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// These are used to test this portion of the compiler, they don't actually
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// mean anything
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("test_accepted_feature", "1.0.0", Accepted),
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("test_removed_feature", "1.0.0", Removed),
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];
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enum Status {
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/// Represents an active feature that is currently being implemented or
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/// currently being considered for addition/removal.
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Active,
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/// Represents a feature gate that is temporarily enabling deprecated behavior.
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/// This gate will never be accepted.
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Deprecated,
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/// Represents a feature which has since been removed (it was once Active)
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Removed,
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/// This language feature has since been Accepted (it was once Active)
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Accepted,
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}
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/// A set of features to be used by later passes.
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pub struct Features {
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pub unboxed_closures: bool,
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pub rustc_diagnostic_macros: bool,
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pub import_shadowing: bool,
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pub visible_private_types: bool,
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pub quote: bool,
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pub old_orphan_check: bool,
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pub simd_ffi: bool,
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pub lib_features: Vec<(InternedString, Span)>
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}
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impl Features {
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pub fn new() -> Features {
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Features {
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unboxed_closures: false,
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rustc_diagnostic_macros: false,
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import_shadowing: false,
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visible_private_types: false,
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quote: false,
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old_orphan_check: false,
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simd_ffi: false,
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lib_features: Vec::new()
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}
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}
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}
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struct Context<'a> {
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features: Vec<&'static str>,
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span_handler: &'a SpanHandler,
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cm: &'a CodeMap,
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}
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impl<'a> Context<'a> {
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fn gate_feature(&self, feature: &str, span: Span, explain: &str) {
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if !self.has_feature(feature) {
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emit_feature_err(self.span_handler, feature, span, explain);
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}
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}
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fn warn_feature(&self, feature: &str, span: Span, explain: &str) {
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if !self.has_feature(feature) {
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emit_feature_warn(self.span_handler, feature, span, explain);
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}
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}
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fn has_feature(&self, feature: &str) -> bool {
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self.features.iter().any(|&n| n == feature)
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}
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}
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pub fn emit_feature_err(diag: &SpanHandler, feature: &str, span: Span, explain: &str) {
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diag.span_err(span, explain);
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diag.span_help(span, &format!("add #![feature({})] to the \
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crate attributes to enable",
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feature)[]);
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}
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pub fn emit_feature_warn(diag: &SpanHandler, feature: &str, span: Span, explain: &str) {
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diag.span_warn(span, explain);
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diag.span_help(span, &format!("add #![feature({})] to the \
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crate attributes to silence this warning",
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feature)[]);
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}
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struct MacroVisitor<'a> {
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context: &'a Context<'a>
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}
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impl<'a, 'v> Visitor<'v> for MacroVisitor<'a> {
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fn visit_mac(&mut self, mac: &ast::Mac) {
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let ast::MacInvocTT(ref path, _, _) = mac.node;
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let id = path.segments.last().unwrap().identifier;
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if id == token::str_to_ident("asm") {
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self.context.gate_feature("asm", path.span, "inline assembly is not \
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stable enough for use and is subject to change");
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}
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else if id == token::str_to_ident("log_syntax") {
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self.context.gate_feature("log_syntax", path.span, "`log_syntax!` is not \
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stable enough for use and is subject to change");
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}
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else if id == token::str_to_ident("trace_macros") {
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self.context.gate_feature("trace_macros", path.span, "`trace_macros` is not \
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stable enough for use and is subject to change");
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}
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else if id == token::str_to_ident("concat_idents") {
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self.context.gate_feature("concat_idents", path.span, "`concat_idents` is not \
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stable enough for use and is subject to change");
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}
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}
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}
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struct PostExpansionVisitor<'a> {
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context: &'a Context<'a>
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}
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impl<'a> PostExpansionVisitor<'a> {
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fn gate_feature(&self, feature: &str, span: Span, explain: &str) {
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if !self.context.cm.span_is_internal(span) {
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self.context.gate_feature(feature, span, explain)
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}
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}
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}
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impl<'a, 'v> Visitor<'v> for PostExpansionVisitor<'a> {
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fn visit_name(&mut self, sp: Span, name: ast::Name) {
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if !token::get_name(name).get().is_ascii() {
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self.gate_feature("non_ascii_idents", sp,
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"non-ascii idents are not fully supported.");
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}
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}
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fn visit_view_item(&mut self, i: &ast::ViewItem) {
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match i.node {
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ast::ViewItemUse(..) => {}
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ast::ViewItemExternCrate(..) => {
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for attr in i.attrs.iter() {
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if attr.check_name("plugin") {
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self.gate_feature("plugin", attr.span,
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"compiler plugins are experimental \
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and possibly buggy");
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}
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}
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}
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}
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visit::walk_view_item(self, i)
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}
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fn visit_item(&mut self, i: &ast::Item) {
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for attr in i.attrs.iter() {
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if attr.name() == "thread_local" {
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self.gate_feature("thread_local", i.span,
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"`#[thread_local]` is an experimental feature, and does not \
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currently handle destructors. There is no corresponding \
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`#[task_local]` mapping to the task model");
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} else if attr.name() == "linkage" {
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self.gate_feature("linkage", i.span,
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"the `linkage` attribute is experimental \
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and not portable across platforms")
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} else if attr.name() == "rustc_on_unimplemented" {
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self.gate_feature("on_unimplemented", i.span,
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"the `#[rustc_on_unimplemented]` attribute \
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is an experimental feature")
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}
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}
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match i.node {
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ast::ItemForeignMod(ref foreign_module) => {
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if attr::contains_name(&i.attrs[], "link_args") {
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self.gate_feature("link_args", i.span,
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"the `link_args` attribute is not portable \
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across platforms, it is recommended to \
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use `#[link(name = \"foo\")]` instead")
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}
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if foreign_module.abi == RustIntrinsic {
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self.gate_feature("intrinsics",
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i.span,
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"intrinsics are subject to change")
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}
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}
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ast::ItemFn(..) => {
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if attr::contains_name(&i.attrs[], "plugin_registrar") {
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self.gate_feature("plugin_registrar", i.span,
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"compiler plugins are experimental and possibly buggy");
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}
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if attr::contains_name(&i.attrs[], "start") {
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self.gate_feature("start", i.span,
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"a #[start] function is an experimental \
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feature whose signature may change \
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over time");
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}
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if attr::contains_name(&i.attrs[], "main") {
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self.gate_feature("main", i.span,
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"declaration of a nonstandard #[main] \
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function may change over time, for now \
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a top-level `fn main()` is required");
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}
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}
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ast::ItemStruct(..) => {
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if attr::contains_name(&i.attrs[], "simd") {
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self.gate_feature("simd", i.span,
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"SIMD types are experimental and possibly buggy");
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}
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}
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ast::ItemImpl(_, polarity, _, _, _, _) => {
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match polarity {
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ast::ImplPolarity::Negative => {
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self.gate_feature("optin_builtin_traits",
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i.span,
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"negative trait bounds are not yet fully implemented; \
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use marker types for now");
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},
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_ => {}
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}
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if attr::contains_name(i.attrs.as_slice(),
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"unsafe_destructor") {
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self.gate_feature("unsafe_destructor",
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i.span,
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"`#[unsafe_destructor]` allows too \
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many unsafe patterns and may be \
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removed in the future");
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}
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if attr::contains_name(&i.attrs[],
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"old_orphan_check") {
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self.gate_feature(
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"old_orphan_check",
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i.span,
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"the new orphan check rules will eventually be strictly enforced");
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}
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if attr::contains_name(&i.attrs[],
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"old_impl_check") {
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self.gate_feature("old_impl_check",
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i.span,
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"`#[old_impl_check]` will be removed in the future");
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}
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}
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_ => {}
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}
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visit::walk_item(self, i);
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}
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fn visit_foreign_item(&mut self, i: &ast::ForeignItem) {
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if attr::contains_name(&i.attrs[], "linkage") {
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self.gate_feature("linkage", i.span,
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"the `linkage` attribute is experimental \
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and not portable across platforms")
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}
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let links_to_llvm = match attr::first_attr_value_str_by_name(i.attrs.as_slice(),
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"link_name") {
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Some(val) => val.get().starts_with("llvm."),
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_ => false
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};
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if links_to_llvm {
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self.gate_feature("link_llvm_intrinsics", i.span,
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"linking to LLVM intrinsics is experimental");
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}
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visit::walk_foreign_item(self, i)
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}
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fn visit_ty(&mut self, t: &ast::Ty) {
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match t.node {
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ast::TyPath(ref p, _) => {
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match &*p.segments {
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[ast::PathSegment { identifier, .. }] => {
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let name = token::get_ident(identifier);
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let msg = if name == "int" {
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Some("the `int` type is deprecated; \
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use `isize` or a fixed-sized integer")
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} else if name == "uint" {
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Some("the `uint` type is deprecated; \
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use `usize` or a fixed-sized integer")
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} else {
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None
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};
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if let Some(msg) = msg {
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self.context.warn_feature("int_uint", t.span, msg)
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}
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}
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_ => {}
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}
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}
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_ => {}
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}
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visit::walk_ty(self, t);
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}
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fn visit_expr(&mut self, e: &ast::Expr) {
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match e.node {
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ast::ExprBox(..) | ast::ExprUnary(ast::UnOp::UnUniq, _) => {
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self.gate_feature("box_syntax",
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e.span,
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"box expression syntax is experimental in alpha release; \
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you can call `Box::new` instead.");
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}
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ast::ExprLit(ref lit) => {
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match lit.node {
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ast::LitInt(_, ty) => {
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let msg = if let ast::SignedIntLit(ast::TyIs(true), _) = ty {
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Some("the `i` suffix on integers is deprecated; use `is` \
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or one of the fixed-sized suffixes")
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} else if let ast::UnsignedIntLit(ast::TyUs(true)) = ty {
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Some("the `u` suffix on integers is deprecated; use `us` \
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or one of the fixed-sized suffixes")
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} else {
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None
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};
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if let Some(msg) = msg {
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self.context.warn_feature("int_uint", e.span, msg);
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}
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}
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_ => {}
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}
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}
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_ => {}
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}
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visit::walk_expr(self, e);
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}
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fn visit_attribute(&mut self, attr: &ast::Attribute) {
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if attr::contains_name(slice::ref_slice(attr), "lang") {
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self.gate_feature("lang_items",
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attr.span,
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"language items are subject to change");
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}
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}
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fn visit_pat(&mut self, pattern: &ast::Pat) {
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match pattern.node {
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ast::PatVec(_, Some(_), ref last) if !last.is_empty() => {
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self.gate_feature("advanced_slice_patterns",
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pattern.span,
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"multiple-element slice matches anywhere \
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but at the end of a slice (e.g. \
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`[0, ..xs, 0]` are experimental")
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}
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ast::PatBox(..) => {
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self.gate_feature("box_syntax",
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pattern.span,
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"box pattern syntax is experimental in alpha release");
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}
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_ => {}
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}
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visit::walk_pat(self, pattern)
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}
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fn visit_fn(&mut self,
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fn_kind: visit::FnKind<'v>,
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fn_decl: &'v ast::FnDecl,
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block: &'v ast::Block,
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span: Span,
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_node_id: NodeId) {
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match fn_kind {
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visit::FkItemFn(_, _, _, abi) if abi == RustIntrinsic => {
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self.gate_feature("intrinsics",
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span,
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"intrinsics are subject to change")
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}
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_ => {}
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}
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visit::walk_fn(self, fn_kind, fn_decl, block, span);
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}
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}
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fn check_crate_inner<F>(cm: &CodeMap, span_handler: &SpanHandler, krate: &ast::Crate,
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check: F)
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-> Features
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where F: FnOnce(&mut Context, &ast::Crate)
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{
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let mut cx = Context {
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features: Vec::new(),
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span_handler: span_handler,
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cm: cm,
|
|
};
|
|
|
|
let mut unknown_features = Vec::new();
|
|
|
|
for attr in krate.attrs.iter() {
|
|
if !attr.check_name("feature") {
|
|
continue
|
|
}
|
|
|
|
match attr.meta_item_list() {
|
|
None => {
|
|
span_handler.span_err(attr.span, "malformed feature attribute, \
|
|
expected #![feature(...)]");
|
|
}
|
|
Some(list) => {
|
|
for mi in list.iter() {
|
|
let name = match mi.node {
|
|
ast::MetaWord(ref word) => (*word).clone(),
|
|
_ => {
|
|
span_handler.span_err(mi.span,
|
|
"malformed feature, expected just \
|
|
one word");
|
|
continue
|
|
}
|
|
};
|
|
match KNOWN_FEATURES.iter()
|
|
.find(|& &(n, _, _)| name == n) {
|
|
Some(&(name, _, Active)) => {
|
|
cx.features.push(name);
|
|
}
|
|
Some(&(name, _, Deprecated)) => {
|
|
cx.features.push(name);
|
|
span_handler.span_warn(
|
|
mi.span,
|
|
"feature is deprecated and will only be available \
|
|
for a limited time, please rewrite code that relies on it");
|
|
}
|
|
Some(&(_, _, Removed)) => {
|
|
span_handler.span_err(mi.span, "feature has been removed");
|
|
}
|
|
Some(&(_, _, Accepted)) => {
|
|
span_handler.span_warn(mi.span, "feature has been added to Rust, \
|
|
directive not necessary");
|
|
}
|
|
None => {
|
|
unknown_features.push((name, mi.span));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
check(&mut cx, krate);
|
|
|
|
Features {
|
|
unboxed_closures: cx.has_feature("unboxed_closures"),
|
|
rustc_diagnostic_macros: cx.has_feature("rustc_diagnostic_macros"),
|
|
import_shadowing: cx.has_feature("import_shadowing"),
|
|
visible_private_types: cx.has_feature("visible_private_types"),
|
|
quote: cx.has_feature("quote"),
|
|
old_orphan_check: cx.has_feature("old_orphan_check"),
|
|
simd_ffi: cx.has_feature("simd_ffi"),
|
|
lib_features: unknown_features
|
|
}
|
|
}
|
|
|
|
pub fn check_crate_macros(cm: &CodeMap, span_handler: &SpanHandler, krate: &ast::Crate)
|
|
-> Features {
|
|
check_crate_inner(cm, span_handler, krate,
|
|
|ctx, krate| visit::walk_crate(&mut MacroVisitor { context: ctx }, krate))
|
|
}
|
|
|
|
pub fn check_crate(cm: &CodeMap, span_handler: &SpanHandler, krate: &ast::Crate)
|
|
-> Features {
|
|
check_crate_inner(cm, span_handler, krate,
|
|
|ctx, krate| visit::walk_crate(&mut PostExpansionVisitor { context: ctx },
|
|
krate))
|
|
}
|
|
|