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cfg_attr: avoid .outer_tokens

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This commit is contained in:
Mazdak Farrokhzad 2019-12-05 06:45:50 +01:00
parent 9630dbbc3c
commit bbcda98d41
7 changed files with 178 additions and 76 deletions
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125
src/librustc_parse/config.rs
View File

@ -8,18 +8,20 @@
//!
//! [#64197]: https://github.com/rust-lang/rust/issues/64197
use crate::validate_attr;
use crate::{parse_in, validate_attr};
use rustc_feature::Features;
use rustc_errors::Applicability;
use syntax::attr::HasAttrs;
use syntax::feature_gate::{feature_err, get_features};
use syntax::attr;
use syntax::ast;
use syntax::ast::{self, Attribute, AttrItem, MetaItem};
use syntax::edition::Edition;
use syntax::mut_visit::*;
use syntax::ptr::P;
use syntax::tokenstream::DelimSpan;
use syntax::sess::ParseSess;
use syntax::util::map_in_place::MapInPlace;
use syntax_pos::Span;
use syntax_pos::symbol::sym;
use smallvec::SmallVec;
@ -72,6 +74,11 @@ macro_rules! configure {
}
}
const CFG_ATTR_GRAMMAR_HELP: &str = "#[cfg_attr(condition, attribute, other_attribute, ...)]";
const CFG_ATTR_NOTE_REF: &str = "for more information, visit \
<https://doc.rust-lang.org/reference/conditional-compilation.html\
#the-cfg_attr-attribute>";
impl<'a> StripUnconfigured<'a> {
pub fn configure<T: HasAttrs>(&mut self, mut node: T) -> Option<T> {
self.process_cfg_attrs(&mut node);
@ -97,34 +104,14 @@ impl<'a> StripUnconfigured<'a> {
/// Gives a compiler warning when the `cfg_attr` contains no attributes and
/// is in the original source file. Gives a compiler error if the syntax of
/// the attribute is incorrect.
fn process_cfg_attr(&mut self, attr: ast::Attribute) -> Vec<ast::Attribute> {
fn process_cfg_attr(&mut self, attr: Attribute) -> Vec<Attribute> {
if !attr.has_name(sym::cfg_attr) {
return vec![attr];
}
if let ast::MacArgs::Empty = attr.get_normal_item().args {
self.sess.span_diagnostic
.struct_span_err(
attr.span,
"malformed `cfg_attr` attribute input",
).span_suggestion(
attr.span,
"missing condition and attribute",
"#[cfg_attr(condition, attribute, other_attribute, ...)]".to_owned(),
Applicability::HasPlaceholders,
).note("for more information, visit \
<https://doc.rust-lang.org/reference/conditional-compilation.html\
#the-cfg_attr-attribute>")
.emit();
return vec![];
}
let res = crate::parse_in_attr(self.sess, &attr, |p| p.parse_cfg_attr());
let (cfg_predicate, expanded_attrs) = match res {
Ok(result) => result,
Err(mut e) => {
e.emit();
return vec![];
}
let (cfg_predicate, expanded_attrs) = match self.parse_cfg_attr(&attr) {
None => return vec![],
Some(r) => r,
};
// Lint on zero attributes in source.
@ -135,24 +122,72 @@ impl<'a> StripUnconfigured<'a> {
// At this point we know the attribute is considered used.
attr::mark_used(&attr);
if attr::cfg_matches(&cfg_predicate, self.sess, self.features) {
// We call `process_cfg_attr` recursively in case there's a
// `cfg_attr` inside of another `cfg_attr`. E.g.
// `#[cfg_attr(false, cfg_attr(true, some_attr))]`.
expanded_attrs.into_iter()
.flat_map(|(item, span)| self.process_cfg_attr(attr::mk_attr_from_item(
attr.style,
item,
span,
)))
.collect()
} else {
vec![]
if !attr::cfg_matches(&cfg_predicate, self.sess, self.features) {
return vec![];
}
// We call `process_cfg_attr` recursively in case there's a
// `cfg_attr` inside of another `cfg_attr`. E.g.
// `#[cfg_attr(false, cfg_attr(true, some_attr))]`.
expanded_attrs
.into_iter()
.flat_map(|(item, span)| {
let attr = attr::mk_attr_from_item(attr.style, item, span);
self.process_cfg_attr(attr)
})
.collect()
}
fn parse_cfg_attr(&self, attr: &Attribute) -> Option<(MetaItem, Vec<(AttrItem, Span)>)> {
match &attr.get_normal_item().args {
ast::MacArgs::Delimited(dspan, delim, tts) if !tts.is_empty() => {
if let ast::MacDelimiter::Brace | ast::MacDelimiter::Bracket = delim {
self.error_malformed_cfg_attr_wrong_delim(*dspan);
}
match parse_in(self.sess, tts.clone(), "`cfg_attr` input", |p| p.parse_cfg_attr()) {
Ok(r) => return Some(r),
Err(mut e) => e
.help(&format!("the valid syntax is `{}`", CFG_ATTR_GRAMMAR_HELP))
.note(CFG_ATTR_NOTE_REF)
.emit(),
}
}
_ => self.error_malformed_cfg_attr_missing(attr.span),
}
None
}
fn error_malformed_cfg_attr_wrong_delim(&self, dspan: DelimSpan) {
self.sess
.span_diagnostic
.struct_span_err(dspan.entire(), "wrong `cfg_attr` delimiters")
.multipart_suggestion(
"the delimiters should be `(` and `)`",
vec![
(dspan.open, "(".to_string()),
(dspan.close, ")".to_string()),
],
Applicability::MachineApplicable,
)
.emit();
}
fn error_malformed_cfg_attr_missing(&self, span: Span) {
self.sess
.span_diagnostic
.struct_span_err(span, "malformed `cfg_attr` attribute input")
.span_suggestion(
span,
"missing condition and attribute",
CFG_ATTR_GRAMMAR_HELP.to_string(),
Applicability::HasPlaceholders,
)
.note(CFG_ATTR_NOTE_REF)
.emit();
}
/// Determines if a node with the given attributes should be included in this configuration.
pub fn in_cfg(&self, attrs: &[ast::Attribute]) -> bool {
pub fn in_cfg(&self, attrs: &[Attribute]) -> bool {
attrs.iter().all(|attr| {
if !is_cfg(attr) {
return true;
@ -199,7 +234,7 @@ impl<'a> StripUnconfigured<'a> {
}
/// Visit attributes on expression and statements (but not attributes on items in blocks).
fn visit_expr_attrs(&mut self, attrs: &[ast::Attribute]) {
fn visit_expr_attrs(&mut self, attrs: &[Attribute]) {
// flag the offending attributes
for attr in attrs.iter() {
self.maybe_emit_expr_attr_err(attr);
@ -207,7 +242,7 @@ impl<'a> StripUnconfigured<'a> {
}
/// If attributes are not allowed on expressions, emit an error for `attr`
pub fn maybe_emit_expr_attr_err(&self, attr: &ast::Attribute) {
pub fn maybe_emit_expr_attr_err(&self, attr: &Attribute) {
if !self.features.map(|features| features.stmt_expr_attributes).unwrap_or(true) {
let mut err = feature_err(self.sess,
sym::stmt_expr_attributes,
@ -350,7 +385,7 @@ impl<'a> MutVisitor for StripUnconfigured<'a> {
}
}
fn is_cfg(attr: &ast::Attribute) -> bool {
fn is_cfg(attr: &Attribute) -> bool {
attr.check_name(sym::cfg)
}
@ -359,8 +394,8 @@ fn is_cfg(attr: &ast::Attribute) -> bool {
pub fn process_configure_mod(
sess: &ParseSess,
cfg_mods: bool,
attrs: &[ast::Attribute],
) -> (bool, Vec<ast::Attribute>) {
attrs: &[Attribute],
) -> (bool, Vec<Attribute>) {
// Don't perform gated feature checking.
let mut strip_unconfigured = StripUnconfigured { sess, features: None };
let mut attrs = attrs.to_owned();

27
src/librustc_parse/lib.rs
View File

@ -270,21 +270,13 @@ pub fn stream_to_parser_with_base_dir<'a>(
}
/// Runs the given subparser `f` on the tokens of the given `attr`'s item.
pub fn parse_in_attr<'a, T>(
pub fn parse_in<'a, T>(
sess: &'a ParseSess,
attr: &ast::Attribute,
tts: TokenStream,
name: &'static str,
mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
) -> PResult<'a, T> {
let mut parser = Parser::new(
sess,
// FIXME(#66940, Centril | petrochenkov): refactor this function so it doesn't
// require reconstructing and immediately re-parsing delimiters.
attr.get_normal_item().args.outer_tokens(),
None,
false,
false,
Some("attribute"),
);
let mut parser = Parser::new(sess, tts, None, false, false, Some(name));
let result = f(&mut parser)?;
if parser.token != token::Eof {
parser.unexpected()?;
@ -292,6 +284,17 @@ pub fn parse_in_attr<'a, T>(
Ok(result)
}
/// Runs the given subparser `f` on the tokens of the given `attr`'s item.
pub fn parse_in_attr<'a, T>(
sess: &'a ParseSess,
attr: &ast::Attribute,
f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
) -> PResult<'a, T> {
// FIXME(#66940, Centril | petrochenkov): refactor this function so it doesn't
// require reconstructing and immediately re-parsing delimiters.
parse_in(sess, attr.get_normal_item().args.outer_tokens(), "attribute", f)
}
// NOTE(Centril): The following probably shouldn't be here but it acknowledges the
// fact that architecturally, we are using parsing (read on below to understand why).

12
src/librustc_parse/parser/attr.rs
View File

@ -238,22 +238,18 @@ impl<'a> Parser<'a> {
/// Parses `cfg_attr(pred, attr_item_list)` where `attr_item_list` is comma-delimited.
pub fn parse_cfg_attr(&mut self) -> PResult<'a, (ast::MetaItem, Vec<(ast::AttrItem, Span)>)> {
self.expect(&token::OpenDelim(token::Paren))?;
let cfg_predicate = self.parse_meta_item()?;
self.expect(&token::Comma)?;
// Presumably, the majority of the time there will only be one attr.
let mut expanded_attrs = Vec::with_capacity(1);
while !self.check(&token::CloseDelim(token::Paren)) {
let lo = self.token.span.lo();
while self.token.kind != token::Eof {
let lo = self.token.span;
let item = self.parse_attr_item()?;
expanded_attrs.push((item, self.prev_span.with_lo(lo)));
self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Paren)])?;
expanded_attrs.push((item, lo.to(self.prev_span)));
self.eat(&token::Comma);
}
self.expect(&token::CloseDelim(token::Paren))?;
Ok((cfg_predicate, expanded_attrs))
}

16
src/test/ui/conditional-compilation/cfg-attr-parse.rs
View File

@ -1,11 +1,11 @@
// Parse `cfg_attr` with varying numbers of attributes and trailing commas
// Completely empty `cfg_attr` input
#[cfg_attr()] //~ error: expected identifier, found `)`
#[cfg_attr()] //~ error: malformed `cfg_attr` attribute input
struct NoConfigurationPredicate;
// Zero attributes, zero trailing comma (comma manatory here)
#[cfg_attr(all())] //~ error: expected `,`, found `)`
#[cfg_attr(all())] //~ error: expected `,`, found end of `cfg_attr`
struct A0C0;
// Zero attributes, one trailing comma
@ -40,4 +40,16 @@ struct A2C1;
#[cfg_attr(all(), must_use, deprecated,,)] //~ ERROR expected identifier
struct A2C2;
// Wrong delimiter `[`
#[cfg_attr[all(),,]]
//~^ ERROR wrong `cfg_attr` delimiters
//~| ERROR expected identifier, found `,`
struct BracketZero;
// Wrong delimiter `{`
#[cfg_attr{all(),,}]
//~^ ERROR wrong `cfg_attr` delimiters
//~| ERROR expected identifier, found `,`
struct BraceZero;
fn main() {}

64
src/test/ui/conditional-compilation/cfg-attr-parse.stderr
View File

@ -1,32 +1,86 @@
error: expected identifier, found `)`
--> $DIR/cfg-attr-parse.rs:4:12
error: malformed `cfg_attr` attribute input
--> $DIR/cfg-attr-parse.rs:4:1
|
LL | #[cfg_attr()]
| ^ expected identifier
| ^^^^^^^^^^^^^ help: missing condition and attribute: `#[cfg_attr(condition, attribute, other_attribute, ...)]`
|
= note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
error: expected `,`, found `)`
error: expected `,`, found end of `cfg_attr` input
--> $DIR/cfg-attr-parse.rs:8:17
|
LL | #[cfg_attr(all())]
| ^ expected `,`
|
= help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
= note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
error: expected identifier, found `,`
--> $DIR/cfg-attr-parse.rs:16:18
|
LL | #[cfg_attr(all(),,)]
| ^ expected identifier
|
= help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
= note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
error: expected identifier, found `,`
--> $DIR/cfg-attr-parse.rs:28:28
|
LL | #[cfg_attr(all(), must_use,,)]
| ^ expected identifier
|
= help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
= note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
error: expected identifier, found `,`
--> $DIR/cfg-attr-parse.rs:40:40
|
LL | #[cfg_attr(all(), must_use, deprecated,,)]
| ^ expected identifier
|
= help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
= note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
error: aborting due to 5 previous errors
error: wrong `cfg_attr` delimiters
--> $DIR/cfg-attr-parse.rs:44:11
|
LL | #[cfg_attr[all(),,]]
| ^^^^^^^^^
|
help: the delimiters should be `(` and `)`
|
LL | #[cfg_attr(all(),,)]
| ^ ^
error: expected identifier, found `,`
--> $DIR/cfg-attr-parse.rs:44:18
|
LL | #[cfg_attr[all(),,]]
| ^ expected identifier
|
= help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
= note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
error: wrong `cfg_attr` delimiters
--> $DIR/cfg-attr-parse.rs:50:11
|
LL | #[cfg_attr{all(),,}]
| ^^^^^^^^^
|
help: the delimiters should be `(` and `)`
|
LL | #[cfg_attr(all(),,)]
| ^ ^
error: expected identifier, found `,`
--> $DIR/cfg-attr-parse.rs:50:18
|
LL | #[cfg_attr{all(),,}]
| ^ expected identifier
|
= help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
= note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
error: aborting due to 9 previous errors

2
src/test/ui/malformed/malformed-special-attrs.rs
View File

@ -1,7 +1,7 @@
#[cfg_attr] //~ ERROR malformed `cfg_attr` attribute
struct S1;
#[cfg_attr = ""] //~ ERROR expected `(`, found `=`
#[cfg_attr = ""] //~ ERROR malformed `cfg_attr` attribute
struct S2;
#[derive] //~ ERROR malformed `derive` attribute

8
src/test/ui/malformed/malformed-special-attrs.stderr
View File

@ -6,11 +6,13 @@ LL | #[cfg_attr]
|
= note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
error: expected `(`, found `=`
--> $DIR/malformed-special-attrs.rs:4:12
error: malformed `cfg_attr` attribute input
--> $DIR/malformed-special-attrs.rs:4:1
|
LL | #[cfg_attr = ""]
| ^ expected `(`
| ^^^^^^^^^^^^^^^^ help: missing condition and attribute: `#[cfg_attr(condition, attribute, other_attribute, ...)]`
|
= note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
error: malformed `derive` attribute input
--> $DIR/malformed-special-attrs.rs:7:1