Files
rust/src/libsyntax/ext/expand.rs
2019-08-09 09:40:26 -07:00

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use crate::ast::{self, Block, Ident, LitKind, NodeId, PatKind, Path};
use crate::ast::{MacStmtStyle, StmtKind, ItemKind};
use crate::attr::{self, HasAttrs};
use crate::source_map::{dummy_spanned, respan};
use crate::config::StripUnconfigured;
use crate::ext::base::*;
use crate::ext::proc_macro::collect_derives;
use crate::ext::hygiene::{ExpnId, SyntaxContext, ExpnInfo, ExpnKind};
use crate::ext::tt::macro_rules::annotate_err_with_kind;
use crate::ext::placeholders::{placeholder, PlaceholderExpander};
use crate::feature_gate::{self, Features, GateIssue, is_builtin_attr, emit_feature_err};
use crate::mut_visit::*;
use crate::parse::{DirectoryOwnership, PResult, ParseSess};
use crate::parse::token;
use crate::parse::parser::Parser;
use crate::ptr::P;
use crate::symbol::{sym, Symbol};
use crate::tokenstream::{TokenStream, TokenTree};
use crate::visit::{self, Visitor};
use crate::util::map_in_place::MapInPlace;
use errors::{Applicability, FatalError};
use smallvec::{smallvec, SmallVec};
use syntax_pos::{Span, DUMMY_SP, FileName};
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::sync::Lrc;
use std::fs;
use std::io::ErrorKind;
use std::{iter, mem};
use std::ops::DerefMut;
use std::rc::Rc;
use std::path::PathBuf;
macro_rules! ast_fragments {
(
$($Kind:ident($AstTy:ty) {
$kind_name:expr;
$(one fn $mut_visit_ast:ident; fn $visit_ast:ident;)?
$(many fn $flat_map_ast_elt:ident; fn $visit_ast_elt:ident;)?
fn $make_ast:ident;
})*
) => {
/// A fragment of AST that can be produced by a single macro expansion.
/// Can also serve as an input and intermediate result for macro expansion operations.
pub enum AstFragment {
OptExpr(Option<P<ast::Expr>>),
$($Kind($AstTy),)*
}
/// "Discriminant" of an AST fragment.
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum AstFragmentKind {
OptExpr,
$($Kind,)*
}
impl AstFragmentKind {
pub fn name(self) -> &'static str {
match self {
AstFragmentKind::OptExpr => "expression",
$(AstFragmentKind::$Kind => $kind_name,)*
}
}
fn make_from<'a>(self, result: Box<dyn MacResult + 'a>) -> Option<AstFragment> {
match self {
AstFragmentKind::OptExpr =>
result.make_expr().map(Some).map(AstFragment::OptExpr),
$(AstFragmentKind::$Kind => result.$make_ast().map(AstFragment::$Kind),)*
}
}
}
impl AstFragment {
pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
match self {
AstFragment::OptExpr(expr) => expr,
_ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
}
}
$(pub fn $make_ast(self) -> $AstTy {
match self {
AstFragment::$Kind(ast) => ast,
_ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
}
})*
pub fn mut_visit_with<F: MutVisitor>(&mut self, vis: &mut F) {
match self {
AstFragment::OptExpr(opt_expr) => {
visit_clobber(opt_expr, |opt_expr| {
if let Some(expr) = opt_expr {
vis.filter_map_expr(expr)
} else {
None
}
});
}
$($(AstFragment::$Kind(ast) => vis.$mut_visit_ast(ast),)?)*
$($(AstFragment::$Kind(ast) =>
ast.flat_map_in_place(|ast| vis.$flat_map_ast_elt(ast)),)?)*
}
}
pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
match *self {
AstFragment::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
AstFragment::OptExpr(None) => {}
$($(AstFragment::$Kind(ref ast) => visitor.$visit_ast(ast),)?)*
$($(AstFragment::$Kind(ref ast) => for ast_elt in &ast[..] {
visitor.$visit_ast_elt(ast_elt);
})?)*
}
}
}
impl<'a, 'b> MutVisitor for MacroExpander<'a, 'b> {
fn filter_map_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
self.expand_fragment(AstFragment::OptExpr(Some(expr))).make_opt_expr()
}
$($(fn $mut_visit_ast(&mut self, ast: &mut $AstTy) {
visit_clobber(ast, |ast| self.expand_fragment(AstFragment::$Kind(ast)).$make_ast());
})?)*
$($(fn $flat_map_ast_elt(&mut self, ast_elt: <$AstTy as IntoIterator>::Item) -> $AstTy {
self.expand_fragment(AstFragment::$Kind(smallvec![ast_elt])).$make_ast()
})?)*
}
impl<'a> MacResult for crate::ext::tt::macro_rules::ParserAnyMacro<'a> {
$(fn $make_ast(self: Box<crate::ext::tt::macro_rules::ParserAnyMacro<'a>>)
-> Option<$AstTy> {
Some(self.make(AstFragmentKind::$Kind).$make_ast())
})*
}
}
}
ast_fragments! {
Expr(P<ast::Expr>) { "expression"; one fn visit_expr; fn visit_expr; fn make_expr; }
Pat(P<ast::Pat>) { "pattern"; one fn visit_pat; fn visit_pat; fn make_pat; }
Ty(P<ast::Ty>) { "type"; one fn visit_ty; fn visit_ty; fn make_ty; }
Stmts(SmallVec<[ast::Stmt; 1]>) {
"statement"; many fn flat_map_stmt; fn visit_stmt; fn make_stmts;
}
Items(SmallVec<[P<ast::Item>; 1]>) {
"item"; many fn flat_map_item; fn visit_item; fn make_items;
}
TraitItems(SmallVec<[ast::TraitItem; 1]>) {
"trait item"; many fn flat_map_trait_item; fn visit_trait_item; fn make_trait_items;
}
ImplItems(SmallVec<[ast::ImplItem; 1]>) {
"impl item"; many fn flat_map_impl_item; fn visit_impl_item; fn make_impl_items;
}
ForeignItems(SmallVec<[ast::ForeignItem; 1]>) {
"foreign item"; many fn flat_map_foreign_item; fn visit_foreign_item; fn make_foreign_items;
}
}
impl AstFragmentKind {
fn dummy(self, span: Span) -> AstFragment {
self.make_from(DummyResult::any(span)).expect("couldn't create a dummy AST fragment")
}
fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I)
-> AstFragment {
let mut items = items.into_iter();
match self {
AstFragmentKind::Items =>
AstFragment::Items(items.map(Annotatable::expect_item).collect()),
AstFragmentKind::ImplItems =>
AstFragment::ImplItems(items.map(Annotatable::expect_impl_item).collect()),
AstFragmentKind::TraitItems =>
AstFragment::TraitItems(items.map(Annotatable::expect_trait_item).collect()),
AstFragmentKind::ForeignItems =>
AstFragment::ForeignItems(items.map(Annotatable::expect_foreign_item).collect()),
AstFragmentKind::Stmts =>
AstFragment::Stmts(items.map(Annotatable::expect_stmt).collect()),
AstFragmentKind::Expr => AstFragment::Expr(
items.next().expect("expected exactly one expression").expect_expr()
),
AstFragmentKind::OptExpr =>
AstFragment::OptExpr(items.next().map(Annotatable::expect_expr)),
AstFragmentKind::Pat | AstFragmentKind::Ty =>
panic!("patterns and types aren't annotatable"),
}
}
}
pub struct Invocation {
pub kind: InvocationKind,
fragment_kind: AstFragmentKind,
pub expansion_data: ExpansionData,
}
pub enum InvocationKind {
Bang {
mac: ast::Mac,
span: Span,
},
Attr {
attr: ast::Attribute,
item: Annotatable,
// Required for resolving derive helper attributes.
derives: Vec<Path>,
// We temporarily report errors for attribute macros placed after derives
after_derive: bool,
},
Derive {
path: Path,
item: Annotatable,
},
/// "Invocation" that contains all derives from an item,
/// broken into multiple `Derive` invocations when expanded.
/// FIXME: Find a way to remove it.
DeriveContainer {
derives: Vec<Path>,
item: Annotatable,
},
}
impl Invocation {
pub fn span(&self) -> Span {
match &self.kind {
InvocationKind::Bang { span, .. } => *span,
InvocationKind::Attr { attr, .. } => attr.span,
InvocationKind::Derive { path, .. } => path.span,
InvocationKind::DeriveContainer { item, .. } => item.span(),
}
}
}
pub struct MacroExpander<'a, 'b> {
pub cx: &'a mut ExtCtxt<'b>,
monotonic: bool, // cf. `cx.monotonic_expander()`
}
impl<'a, 'b> MacroExpander<'a, 'b> {
pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
MacroExpander { cx, monotonic }
}
pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
let mut module = ModuleData {
mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
directory: match self.cx.source_map().span_to_unmapped_path(krate.span) {
FileName::Real(path) => path,
other => PathBuf::from(other.to_string()),
},
};
module.directory.pop();
self.cx.root_path = module.directory.clone();
self.cx.current_expansion.module = Rc::new(module);
let orig_mod_span = krate.module.inner;
let krate_item = AstFragment::Items(smallvec![P(ast::Item {
attrs: krate.attrs,
span: krate.span,
node: ast::ItemKind::Mod(krate.module),
ident: Ident::invalid(),
id: ast::DUMMY_NODE_ID,
vis: respan(krate.span.shrink_to_lo(), ast::VisibilityKind::Public),
tokens: None,
})]);
match self.expand_fragment(krate_item).make_items().pop().map(P::into_inner) {
Some(ast::Item { attrs, node: ast::ItemKind::Mod(module), .. }) => {
krate.attrs = attrs;
krate.module = module;
},
None => {
// Resolution failed so we return an empty expansion
krate.attrs = vec![];
krate.module = ast::Mod {
inner: orig_mod_span,
items: vec![],
inline: true,
};
},
_ => unreachable!(),
};
self.cx.trace_macros_diag();
krate
}
// Fully expand all macro invocations in this AST fragment.
fn expand_fragment(&mut self, input_fragment: AstFragment) -> AstFragment {
let orig_expansion_data = self.cx.current_expansion.clone();
self.cx.current_expansion.depth = 0;
// Collect all macro invocations and replace them with placeholders.
let (mut fragment_with_placeholders, mut invocations)
= self.collect_invocations(input_fragment, &[]);
// Optimization: if we resolve all imports now,
// we'll be able to immediately resolve most of imported macros.
self.resolve_imports();
// Resolve paths in all invocations and produce output expanded fragments for them, but
// do not insert them into our input AST fragment yet, only store in `expanded_fragments`.
// The output fragments also go through expansion recursively until no invocations are left.
// Unresolved macros produce dummy outputs as a recovery measure.
invocations.reverse();
let mut expanded_fragments = Vec::new();
let mut derives: FxHashMap<ExpnId, Vec<_>> = FxHashMap::default();
let mut undetermined_invocations = Vec::new();
let (mut progress, mut force) = (false, !self.monotonic);
loop {
let invoc = if let Some(invoc) = invocations.pop() {
invoc
} else {
self.resolve_imports();
if undetermined_invocations.is_empty() { break }
invocations = mem::take(&mut undetermined_invocations);
force = !mem::replace(&mut progress, false);
continue
};
let scope =
if self.monotonic { invoc.expansion_data.id } else { orig_expansion_data.id };
let ext = match self.cx.resolver.resolve_macro_invocation(&invoc, scope, force) {
Ok(ext) => ext,
Err(Indeterminate) => {
undetermined_invocations.push(invoc);
continue
}
};
progress = true;
let ExpansionData { depth, id: expn_id, .. } = invoc.expansion_data;
self.cx.current_expansion = invoc.expansion_data.clone();
self.cx.current_expansion.id = scope;
// FIXME(jseyfried): Refactor out the following logic
let (expanded_fragment, new_invocations) = if let Some(ext) = ext {
let fragment = self.expand_invoc(invoc, &ext.kind);
self.collect_invocations(fragment, &[])
} else if let InvocationKind::DeriveContainer { derives: traits, item } = invoc.kind {
if !item.derive_allowed() {
let attr = attr::find_by_name(item.attrs(), sym::derive)
.expect("`derive` attribute should exist");
let span = attr.span;
let mut err = self.cx.mut_span_err(span,
"`derive` may only be applied to \
structs, enums and unions");
if let ast::AttrStyle::Inner = attr.style {
let trait_list = traits.iter()
.map(|t| t.to_string()).collect::<Vec<_>>();
let suggestion = format!("#[derive({})]", trait_list.join(", "));
err.span_suggestion(
span, "try an outer attribute", suggestion,
// We don't 𝑘𝑛𝑜𝑤 that the following item is an ADT
Applicability::MaybeIncorrect
);
}
err.emit();
}
let mut item = self.fully_configure(item);
item.visit_attrs(|attrs| attrs.retain(|a| a.path != sym::derive));
let derives = derives.entry(invoc.expansion_data.id).or_default();
derives.reserve(traits.len());
invocations.reserve(traits.len());
for path in traits {
let expn_id = ExpnId::fresh(self.cx.current_expansion.id, None);
derives.push(expn_id);
invocations.push(Invocation {
kind: InvocationKind::Derive { path, item: item.clone() },
fragment_kind: invoc.fragment_kind,
expansion_data: ExpansionData {
id: expn_id,
..invoc.expansion_data.clone()
},
});
}
let fragment = invoc.fragment_kind
.expect_from_annotatables(::std::iter::once(item));
self.collect_invocations(fragment, derives)
} else {
unreachable!()
};
if expanded_fragments.len() < depth {
expanded_fragments.push(Vec::new());
}
expanded_fragments[depth - 1].push((expn_id, expanded_fragment));
if !self.cx.ecfg.single_step {
invocations.extend(new_invocations.into_iter().rev());
}
}
self.cx.current_expansion = orig_expansion_data;
// Finally incorporate all the expanded macros into the input AST fragment.
let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
while let Some(expanded_fragments) = expanded_fragments.pop() {
for (mark, expanded_fragment) in expanded_fragments.into_iter().rev() {
let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
placeholder_expander.add(NodeId::placeholder_from_expn_id(mark),
expanded_fragment, derives);
}
}
fragment_with_placeholders.mut_visit_with(&mut placeholder_expander);
fragment_with_placeholders
}
fn resolve_imports(&mut self) {
if self.monotonic {
self.cx.resolver.resolve_imports();
}
}
/// Collects all macro invocations reachable at this time in this AST fragment, and replace
/// them with "placeholders" - dummy macro invocations with specially crafted `NodeId`s.
/// Then call into resolver that builds a skeleton ("reduced graph") of the fragment and
/// prepares data for resolving paths of macro invocations.
fn collect_invocations(&mut self, mut fragment: AstFragment, derives: &[ExpnId])
-> (AstFragment, Vec<Invocation>) {
// Resolve `$crate`s in the fragment for pretty-printing.
self.cx.resolver.resolve_dollar_crates();
let invocations = {
let mut collector = InvocationCollector {
cfg: StripUnconfigured {
sess: self.cx.parse_sess,
features: self.cx.ecfg.features,
},
cx: self.cx,
invocations: Vec::new(),
monotonic: self.monotonic,
};
fragment.mut_visit_with(&mut collector);
collector.invocations
};
if self.monotonic {
self.cx.resolver.visit_ast_fragment_with_placeholders(
self.cx.current_expansion.id, &fragment, derives);
}
(fragment, invocations)
}
fn fully_configure(&mut self, item: Annotatable) -> Annotatable {
let mut cfg = StripUnconfigured {
sess: self.cx.parse_sess,
features: self.cx.ecfg.features,
};
// Since the item itself has already been configured by the InvocationCollector,
// we know that fold result vector will contain exactly one element
match item {
Annotatable::Item(item) => {
Annotatable::Item(cfg.flat_map_item(item).pop().unwrap())
}
Annotatable::TraitItem(item) => {
Annotatable::TraitItem(
item.map(|item| cfg.flat_map_trait_item(item).pop().unwrap()))
}
Annotatable::ImplItem(item) => {
Annotatable::ImplItem(item.map(|item| cfg.flat_map_impl_item(item).pop().unwrap()))
}
Annotatable::ForeignItem(item) => {
Annotatable::ForeignItem(
item.map(|item| cfg.flat_map_foreign_item(item).pop().unwrap())
)
}
Annotatable::Stmt(stmt) => {
Annotatable::Stmt(stmt.map(|stmt| cfg.flat_map_stmt(stmt).pop().unwrap()))
}
Annotatable::Expr(mut expr) => {
Annotatable::Expr({ cfg.visit_expr(&mut expr); expr })
}
}
}
fn expand_invoc(&mut self, invoc: Invocation, ext: &SyntaxExtensionKind) -> AstFragment {
let (fragment_kind, span) = (invoc.fragment_kind, invoc.span());
if fragment_kind == AstFragmentKind::ForeignItems && !self.cx.ecfg.macros_in_extern() {
if let SyntaxExtensionKind::NonMacroAttr { .. } = ext {} else {
emit_feature_err(&self.cx.parse_sess, sym::macros_in_extern,
span, GateIssue::Language,
"macro invocations in `extern {}` blocks are experimental");
}
}
if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
let info = self.cx.current_expansion.id.expn_info().unwrap();
let suggested_limit = self.cx.ecfg.recursion_limit * 2;
let mut err = self.cx.struct_span_err(info.call_site,
&format!("recursion limit reached while expanding the macro `{}`",
info.kind.descr()));
err.help(&format!(
"consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
suggested_limit));
err.emit();
self.cx.trace_macros_diag();
FatalError.raise();
}
match invoc.kind {
InvocationKind::Bang { mac, .. } => match ext {
SyntaxExtensionKind::Bang(expander) => {
self.gate_proc_macro_expansion_kind(span, fragment_kind);
let tok_result = expander.expand(self.cx, span, mac.node.stream());
let result =
self.parse_ast_fragment(tok_result, fragment_kind, &mac.node.path, span);
self.gate_proc_macro_expansion(span, &result);
result
}
SyntaxExtensionKind::LegacyBang(expander) => {
let prev = self.cx.current_expansion.prior_type_ascription;
self.cx.current_expansion.prior_type_ascription =
mac.node.prior_type_ascription;
let tok_result = expander.expand(self.cx, span, mac.node.stream());
let result = if let Some(result) = fragment_kind.make_from(tok_result) {
result
} else {
let msg = format!("non-{kind} macro in {kind} position: {path}",
kind = fragment_kind.name(), path = mac.node.path);
self.cx.span_err(span, &msg);
self.cx.trace_macros_diag();
fragment_kind.dummy(span)
};
self.cx.current_expansion.prior_type_ascription = prev;
result
}
_ => unreachable!()
}
InvocationKind::Attr { attr, mut item, .. } => match ext {
SyntaxExtensionKind::Attr(expander) => {
self.gate_proc_macro_attr_item(span, &item);
let item_tok = TokenTree::token(token::Interpolated(Lrc::new(match item {
Annotatable::Item(item) => token::NtItem(item),
Annotatable::TraitItem(item) => token::NtTraitItem(item.into_inner()),
Annotatable::ImplItem(item) => token::NtImplItem(item.into_inner()),
Annotatable::ForeignItem(item) => token::NtForeignItem(item.into_inner()),
Annotatable::Stmt(stmt) => token::NtStmt(stmt.into_inner()),
Annotatable::Expr(expr) => token::NtExpr(expr),
})), DUMMY_SP).into();
let input = self.extract_proc_macro_attr_input(attr.tokens, span);
let tok_result = expander.expand(self.cx, span, input, item_tok);
let res = self.parse_ast_fragment(tok_result, fragment_kind, &attr.path, span);
self.gate_proc_macro_expansion(span, &res);
res
}
SyntaxExtensionKind::LegacyAttr(expander) => {
match attr.parse_meta(self.cx.parse_sess) {
Ok(meta) => {
let item = expander.expand(self.cx, span, &meta, item);
fragment_kind.expect_from_annotatables(item)
}
Err(mut err) => {
err.emit();
fragment_kind.dummy(span)
}
}
}
SyntaxExtensionKind::NonMacroAttr { mark_used } => {
attr::mark_known(&attr);
if *mark_used {
attr::mark_used(&attr);
}
item.visit_attrs(|attrs| attrs.push(attr));
fragment_kind.expect_from_annotatables(iter::once(item))
}
_ => unreachable!()
}
InvocationKind::Derive { path, item } => match ext {
SyntaxExtensionKind::Derive(expander) |
SyntaxExtensionKind::LegacyDerive(expander) => {
if !item.derive_allowed() {
return fragment_kind.dummy(span);
}
let meta = ast::MetaItem { node: ast::MetaItemKind::Word, span, path };
let span = span.with_ctxt(self.cx.backtrace());
let items = expander.expand(self.cx, span, &meta, item);
fragment_kind.expect_from_annotatables(items)
}
_ => unreachable!()
}
InvocationKind::DeriveContainer { .. } => unreachable!()
}
}
fn extract_proc_macro_attr_input(&self, tokens: TokenStream, span: Span) -> TokenStream {
let mut trees = tokens.trees();
match trees.next() {
Some(TokenTree::Delimited(_, _, tts)) => {
if trees.next().is_none() {
return tts.into()
}
}
Some(TokenTree::Token(..)) => {}
None => return TokenStream::empty(),
}
self.cx.span_err(span, "custom attribute invocations must be \
of the form `#[foo]` or `#[foo(..)]`, the macro name must only be \
followed by a delimiter token");
TokenStream::empty()
}
fn gate_proc_macro_attr_item(&self, span: Span, item: &Annotatable) {
let (kind, gate) = match *item {
Annotatable::Item(ref item) => {
match item.node {
ItemKind::Mod(_) if self.cx.ecfg.proc_macro_hygiene() => return,
ItemKind::Mod(_) => ("modules", sym::proc_macro_hygiene),
_ => return,
}
}
Annotatable::TraitItem(_) => return,
Annotatable::ImplItem(_) => return,
Annotatable::ForeignItem(_) => return,
Annotatable::Stmt(_) |
Annotatable::Expr(_) if self.cx.ecfg.proc_macro_hygiene() => return,
Annotatable::Stmt(_) => ("statements", sym::proc_macro_hygiene),
Annotatable::Expr(_) => ("expressions", sym::proc_macro_hygiene),
};
emit_feature_err(
self.cx.parse_sess,
gate,
span,
GateIssue::Language,
&format!("custom attributes cannot be applied to {}", kind),
);
}
fn gate_proc_macro_expansion(&self, span: Span, fragment: &AstFragment) {
if self.cx.ecfg.proc_macro_hygiene() {
return
}
fragment.visit_with(&mut DisallowMacros {
span,
parse_sess: self.cx.parse_sess,
});
struct DisallowMacros<'a> {
span: Span,
parse_sess: &'a ParseSess,
}
impl<'ast, 'a> Visitor<'ast> for DisallowMacros<'a> {
fn visit_item(&mut self, i: &'ast ast::Item) {
if let ast::ItemKind::MacroDef(_) = i.node {
emit_feature_err(
self.parse_sess,
sym::proc_macro_hygiene,
self.span,
GateIssue::Language,
"procedural macros cannot expand to macro definitions",
);
}
visit::walk_item(self, i);
}
fn visit_mac(&mut self, _mac: &'ast ast::Mac) {
// ...
}
}
}
fn gate_proc_macro_expansion_kind(&self, span: Span, kind: AstFragmentKind) {
let kind = match kind {
AstFragmentKind::Expr => "expressions",
AstFragmentKind::OptExpr => "expressions",
AstFragmentKind::Pat => "patterns",
AstFragmentKind::Ty => "types",
AstFragmentKind::Stmts => "statements",
AstFragmentKind::Items => return,
AstFragmentKind::TraitItems => return,
AstFragmentKind::ImplItems => return,
AstFragmentKind::ForeignItems => return,
};
if self.cx.ecfg.proc_macro_hygiene() {
return
}
emit_feature_err(
self.cx.parse_sess,
sym::proc_macro_hygiene,
span,
GateIssue::Language,
&format!("procedural macros cannot be expanded to {}", kind),
);
}
fn parse_ast_fragment(
&mut self,
toks: TokenStream,
kind: AstFragmentKind,
path: &Path,
span: Span,
) -> AstFragment {
let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
match parser.parse_ast_fragment(kind, false) {
Ok(fragment) => {
parser.ensure_complete_parse(path, kind.name(), span);
fragment
}
Err(mut err) => {
err.set_span(span);
annotate_err_with_kind(&mut err, kind, span);
err.emit();
self.cx.trace_macros_diag();
kind.dummy(span)
}
}
}
}
impl<'a> Parser<'a> {
pub fn parse_ast_fragment(&mut self, kind: AstFragmentKind, macro_legacy_warnings: bool)
-> PResult<'a, AstFragment> {
Ok(match kind {
AstFragmentKind::Items => {
let mut items = SmallVec::new();
while let Some(item) = self.parse_item()? {
items.push(item);
}
AstFragment::Items(items)
}
AstFragmentKind::TraitItems => {
let mut items = SmallVec::new();
while self.token != token::Eof {
items.push(self.parse_trait_item(&mut false)?);
}
AstFragment::TraitItems(items)
}
AstFragmentKind::ImplItems => {
let mut items = SmallVec::new();
while self.token != token::Eof {
items.push(self.parse_impl_item(&mut false)?);
}
AstFragment::ImplItems(items)
}
AstFragmentKind::ForeignItems => {
let mut items = SmallVec::new();
while self.token != token::Eof {
items.push(self.parse_foreign_item(DUMMY_SP)?);
}
AstFragment::ForeignItems(items)
}
AstFragmentKind::Stmts => {
let mut stmts = SmallVec::new();
while self.token != token::Eof &&
// won't make progress on a `}`
self.token != token::CloseDelim(token::Brace) {
if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
stmts.push(stmt);
}
}
AstFragment::Stmts(stmts)
}
AstFragmentKind::Expr => AstFragment::Expr(self.parse_expr()?),
AstFragmentKind::OptExpr => {
if self.token != token::Eof {
AstFragment::OptExpr(Some(self.parse_expr()?))
} else {
AstFragment::OptExpr(None)
}
},
AstFragmentKind::Ty => AstFragment::Ty(self.parse_ty()?),
AstFragmentKind::Pat => AstFragment::Pat(self.parse_pat(None)?),
})
}
pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
if self.token != token::Eof {
let msg = format!("macro expansion ignores token `{}` and any following",
self.this_token_to_string());
// Avoid emitting backtrace info twice.
let def_site_span = self.token.span.with_ctxt(SyntaxContext::empty());
let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
err.span_label(span, "caused by the macro expansion here");
let msg = format!(
"the usage of `{}!` is likely invalid in {} context",
macro_path,
kind_name,
);
err.note(&msg);
let semi_span = self.sess.source_map().next_point(span);
let semi_full_span = semi_span.to(self.sess.source_map().next_point(semi_span));
match self.sess.source_map().span_to_snippet(semi_full_span) {
Ok(ref snippet) if &snippet[..] != ";" && kind_name == "expression" => {
err.span_suggestion(
semi_span,
"you might be missing a semicolon here",
";".to_owned(),
Applicability::MaybeIncorrect,
);
}
_ => {}
}
err.emit();
}
}
}
struct InvocationCollector<'a, 'b> {
cx: &'a mut ExtCtxt<'b>,
cfg: StripUnconfigured<'a>,
invocations: Vec<Invocation>,
monotonic: bool,
}
impl<'a, 'b> InvocationCollector<'a, 'b> {
fn collect(&mut self, fragment_kind: AstFragmentKind, kind: InvocationKind) -> AstFragment {
// Expansion info for all the collected invocations is set upon their resolution,
// with exception of the derive container case which is not resolved and can get
// its expansion info immediately.
let expn_info = match &kind {
InvocationKind::DeriveContainer { item, .. } => Some(ExpnInfo::default(
ExpnKind::Macro(MacroKind::Attr, sym::derive),
item.span(), self.cx.parse_sess.edition,
)),
_ => None,
};
let expn_id = ExpnId::fresh(self.cx.current_expansion.id, expn_info);
self.invocations.push(Invocation {
kind,
fragment_kind,
expansion_data: ExpansionData {
id: expn_id,
depth: self.cx.current_expansion.depth + 1,
..self.cx.current_expansion.clone()
},
});
placeholder(fragment_kind, NodeId::placeholder_from_expn_id(expn_id))
}
fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: AstFragmentKind) -> AstFragment {
self.collect(kind, InvocationKind::Bang { mac, span })
}
fn collect_attr(&mut self,
attr: Option<ast::Attribute>,
derives: Vec<Path>,
item: Annotatable,
kind: AstFragmentKind,
after_derive: bool)
-> AstFragment {
self.collect(kind, match attr {
Some(attr) => InvocationKind::Attr { attr, item, derives, after_derive },
None => InvocationKind::DeriveContainer { derives, item },
})
}
fn find_attr_invoc(&self, attrs: &mut Vec<ast::Attribute>, after_derive: &mut bool)
-> Option<ast::Attribute> {
let attr = attrs.iter()
.position(|a| {
if a.path == sym::derive {
*after_derive = true;
}
!attr::is_known(a) && !is_builtin_attr(a)
})
.map(|i| attrs.remove(i));
if let Some(attr) = &attr {
if !self.cx.ecfg.custom_inner_attributes() &&
attr.style == ast::AttrStyle::Inner && attr.path != sym::test {
emit_feature_err(&self.cx.parse_sess, sym::custom_inner_attributes,
attr.span, GateIssue::Language,
"non-builtin inner attributes are unstable");
}
}
attr
}
/// If `item` is an attr invocation, remove and return the macro attribute and derive traits.
fn classify_item<T>(&mut self, item: &mut T)
-> (Option<ast::Attribute>, Vec<Path>, /* after_derive */ bool)
where T: HasAttrs,
{
let (mut attr, mut traits, mut after_derive) = (None, Vec::new(), false);
item.visit_attrs(|mut attrs| {
attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
traits = collect_derives(&mut self.cx, &mut attrs);
});
(attr, traits, after_derive)
}
/// Alternative to `classify_item()` that ignores `#[derive]` so invocations fallthrough
/// to the unused-attributes lint (making it an error on statements and expressions
/// is a breaking change)
fn classify_nonitem<T: HasAttrs>(&mut self, nonitem: &mut T)
-> (Option<ast::Attribute>, /* after_derive */ bool) {
let (mut attr, mut after_derive) = (None, false);
nonitem.visit_attrs(|mut attrs| {
attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
});
(attr, after_derive)
}
fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
self.cfg.configure(node)
}
// Detect use of feature-gated or invalid attributes on macro invocations
// since they will not be detected after macro expansion.
fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
let features = self.cx.ecfg.features.unwrap();
for attr in attrs.iter() {
self.check_attribute_inner(attr, features);
// macros are expanded before any lint passes so this warning has to be hardcoded
if attr.path == sym::derive {
self.cx.struct_span_warn(attr.span, "`#[derive]` does nothing on macro invocations")
.note("this may become a hard error in a future release")
.emit();
}
}
}
fn check_attribute(&mut self, at: &ast::Attribute) {
let features = self.cx.ecfg.features.unwrap();
self.check_attribute_inner(at, features);
}
fn check_attribute_inner(&mut self, at: &ast::Attribute, features: &Features) {
feature_gate::check_attribute(at, self.cx.parse_sess, features);
}
}
impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
fn visit_expr(&mut self, expr: &mut P<ast::Expr>) {
self.cfg.configure_expr(expr);
visit_clobber(expr.deref_mut(), |mut expr| {
self.cfg.configure_expr_kind(&mut expr.node);
// ignore derives so they remain unused
let (attr, after_derive) = self.classify_nonitem(&mut expr);
if attr.is_some() {
// Collect the invoc regardless of whether or not attributes are permitted here
// expansion will eat the attribute so it won't error later.
attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
// AstFragmentKind::Expr requires the macro to emit an expression.
return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
AstFragmentKind::Expr, after_derive)
.make_expr()
.into_inner()
}
if let ast::ExprKind::Mac(mac) = expr.node {
self.check_attributes(&expr.attrs);
self.collect_bang(mac, expr.span, AstFragmentKind::Expr)
.make_expr()
.into_inner()
} else {
noop_visit_expr(&mut expr, self);
expr
}
});
}
fn filter_map_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
let expr = configure!(self, expr);
expr.filter_map(|mut expr| {
self.cfg.configure_expr_kind(&mut expr.node);
// Ignore derives so they remain unused.
let (attr, after_derive) = self.classify_nonitem(&mut expr);
if attr.is_some() {
attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
AstFragmentKind::OptExpr, after_derive)
.make_opt_expr()
.map(|expr| expr.into_inner())
}
if let ast::ExprKind::Mac(mac) = expr.node {
self.check_attributes(&expr.attrs);
self.collect_bang(mac, expr.span, AstFragmentKind::OptExpr)
.make_opt_expr()
.map(|expr| expr.into_inner())
} else {
Some({ noop_visit_expr(&mut expr, self); expr })
}
})
}
fn visit_pat(&mut self, pat: &mut P<ast::Pat>) {
self.cfg.configure_pat(pat);
match pat.node {
PatKind::Mac(_) => {}
_ => return noop_visit_pat(pat, self),
}
visit_clobber(pat, |mut pat| {
match mem::replace(&mut pat.node, PatKind::Wild) {
PatKind::Mac(mac) =>
self.collect_bang(mac, pat.span, AstFragmentKind::Pat).make_pat(),
_ => unreachable!(),
}
});
}
fn flat_map_stmt(&mut self, stmt: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> {
let mut stmt = configure!(self, stmt);
// we'll expand attributes on expressions separately
if !stmt.is_expr() {
let (attr, derives, after_derive) = if stmt.is_item() {
self.classify_item(&mut stmt)
} else {
// ignore derives on non-item statements so it falls through
// to the unused-attributes lint
let (attr, after_derive) = self.classify_nonitem(&mut stmt);
(attr, vec![], after_derive)
};
if attr.is_some() || !derives.is_empty() {
return self.collect_attr(attr, derives, Annotatable::Stmt(P(stmt)),
AstFragmentKind::Stmts, after_derive).make_stmts();
}
}
if let StmtKind::Mac(mac) = stmt.node {
let (mac, style, attrs) = mac.into_inner();
self.check_attributes(&attrs);
let mut placeholder = self.collect_bang(mac, stmt.span, AstFragmentKind::Stmts)
.make_stmts();
// If this is a macro invocation with a semicolon, then apply that
// semicolon to the final statement produced by expansion.
if style == MacStmtStyle::Semicolon {
if let Some(stmt) = placeholder.pop() {
placeholder.push(stmt.add_trailing_semicolon());
}
}
return placeholder;
}
// The placeholder expander gives ids to statements, so we avoid folding the id here.
let ast::Stmt { id, node, span } = stmt;
noop_flat_map_stmt_kind(node, self).into_iter().map(|node| {
ast::Stmt { id, node, span }
}).collect()
}
fn visit_block(&mut self, block: &mut P<Block>) {
let old_directory_ownership = self.cx.current_expansion.directory_ownership;
self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
noop_visit_block(block, self);
self.cx.current_expansion.directory_ownership = old_directory_ownership;
}
fn flat_map_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
let mut item = configure!(self, item);
let (attr, traits, after_derive) = self.classify_item(&mut item);
if attr.is_some() || !traits.is_empty() {
return self.collect_attr(attr, traits, Annotatable::Item(item),
AstFragmentKind::Items, after_derive).make_items();
}
match item.node {
ast::ItemKind::Mac(..) => {
self.check_attributes(&item.attrs);
item.and_then(|item| match item.node {
ItemKind::Mac(mac) => self.collect(
AstFragmentKind::Items, InvocationKind::Bang { mac, span: item.span }
).make_items(),
_ => unreachable!(),
})
}
ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
if item.ident == Ident::invalid() {
return noop_flat_map_item(item, self);
}
let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
let mut module = (*self.cx.current_expansion.module).clone();
module.mod_path.push(item.ident);
// Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
// In the non-inline case, `inner` is never the dummy span (cf. `parse_item_mod`).
// Thus, if `inner` is the dummy span, we know the module is inline.
let inline_module = item.span.contains(inner) || inner.is_dummy();
if inline_module {
if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, sym::path) {
self.cx.current_expansion.directory_ownership =
DirectoryOwnership::Owned { relative: None };
module.directory.push(&*path.as_str());
} else {
module.directory.push(&*item.ident.as_str());
}
} else {
let path = self.cx.parse_sess.source_map().span_to_unmapped_path(inner);
let mut path = match path {
FileName::Real(path) => path,
other => PathBuf::from(other.to_string()),
};
let directory_ownership = match path.file_name().unwrap().to_str() {
Some("mod.rs") => DirectoryOwnership::Owned { relative: None },
Some(_) => DirectoryOwnership::Owned {
relative: Some(item.ident),
},
None => DirectoryOwnership::UnownedViaMod(false),
};
path.pop();
module.directory = path;
self.cx.current_expansion.directory_ownership = directory_ownership;
}
let orig_module =
mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
let result = noop_flat_map_item(item, self);
self.cx.current_expansion.module = orig_module;
self.cx.current_expansion.directory_ownership = orig_directory_ownership;
result
}
_ => noop_flat_map_item(item, self),
}
}
fn flat_map_trait_item(&mut self, item: ast::TraitItem) -> SmallVec<[ast::TraitItem; 1]> {
let mut item = configure!(self, item);
let (attr, traits, after_derive) = self.classify_item(&mut item);
if attr.is_some() || !traits.is_empty() {
return self.collect_attr(attr, traits, Annotatable::TraitItem(P(item)),
AstFragmentKind::TraitItems, after_derive).make_trait_items()
}
match item.node {
ast::TraitItemKind::Macro(mac) => {
let ast::TraitItem { attrs, span, .. } = item;
self.check_attributes(&attrs);
self.collect_bang(mac, span, AstFragmentKind::TraitItems).make_trait_items()
}
_ => noop_flat_map_trait_item(item, self),
}
}
fn flat_map_impl_item(&mut self, item: ast::ImplItem) -> SmallVec<[ast::ImplItem; 1]> {
let mut item = configure!(self, item);
let (attr, traits, after_derive) = self.classify_item(&mut item);
if attr.is_some() || !traits.is_empty() {
return self.collect_attr(attr, traits, Annotatable::ImplItem(P(item)),
AstFragmentKind::ImplItems, after_derive).make_impl_items();
}
match item.node {
ast::ImplItemKind::Macro(mac) => {
let ast::ImplItem { attrs, span, .. } = item;
self.check_attributes(&attrs);
self.collect_bang(mac, span, AstFragmentKind::ImplItems).make_impl_items()
}
_ => noop_flat_map_impl_item(item, self),
}
}
fn visit_ty(&mut self, ty: &mut P<ast::Ty>) {
match ty.node {
ast::TyKind::Mac(_) => {}
_ => return noop_visit_ty(ty, self),
};
visit_clobber(ty, |mut ty| {
match mem::replace(&mut ty.node, ast::TyKind::Err) {
ast::TyKind::Mac(mac) =>
self.collect_bang(mac, ty.span, AstFragmentKind::Ty).make_ty(),
_ => unreachable!(),
}
});
}
fn visit_foreign_mod(&mut self, foreign_mod: &mut ast::ForeignMod) {
self.cfg.configure_foreign_mod(foreign_mod);
noop_visit_foreign_mod(foreign_mod, self);
}
fn flat_map_foreign_item(&mut self, mut foreign_item: ast::ForeignItem)
-> SmallVec<[ast::ForeignItem; 1]>
{
let (attr, traits, after_derive) = self.classify_item(&mut foreign_item);
if attr.is_some() || !traits.is_empty() {
return self.collect_attr(attr, traits, Annotatable::ForeignItem(P(foreign_item)),
AstFragmentKind::ForeignItems, after_derive)
.make_foreign_items();
}
if let ast::ForeignItemKind::Macro(mac) = foreign_item.node {
self.check_attributes(&foreign_item.attrs);
return self.collect_bang(mac, foreign_item.span, AstFragmentKind::ForeignItems)
.make_foreign_items();
}
noop_flat_map_foreign_item(foreign_item, self)
}
fn visit_item_kind(&mut self, item: &mut ast::ItemKind) {
match item {
ast::ItemKind::MacroDef(..) => {}
_ => {
self.cfg.configure_item_kind(item);
noop_visit_item_kind(item, self);
}
}
}
fn visit_generic_params(&mut self, params: &mut Vec<ast::GenericParam>) {
self.cfg.configure_generic_params(params);
noop_visit_generic_params(params, self);
}
fn visit_attribute(&mut self, at: &mut ast::Attribute) {
// turn `#[doc(include="filename")]` attributes into `#[doc(include(file="filename",
// contents="file contents")]` attributes
if !at.check_name(sym::doc) {
return noop_visit_attribute(at, self);
}
if let Some(list) = at.meta_item_list() {
if !list.iter().any(|it| it.check_name(sym::include)) {
return noop_visit_attribute(at, self);
}
let mut items = vec![];
for mut it in list {
if !it.check_name(sym::include) {
items.push({ noop_visit_meta_list_item(&mut it, self); it });
continue;
}
if let Some(file) = it.value_str() {
let err_count = self.cx.parse_sess.span_diagnostic.err_count();
self.check_attribute(&at);
if self.cx.parse_sess.span_diagnostic.err_count() > err_count {
// avoid loading the file if they haven't enabled the feature
return noop_visit_attribute(at, self);
}
let filename = self.cx.resolve_path(&*file.as_str(), it.span());
match fs::read_to_string(&filename) {
Ok(src) => {
let src_interned = Symbol::intern(&src);
// Add this input file to the code map to make it available as
// dependency information
self.cx.source_map().new_source_file(filename.into(), src);
let include_info = vec![
ast::NestedMetaItem::MetaItem(
attr::mk_name_value_item_str(
Ident::with_empty_ctxt(sym::file),
dummy_spanned(file),
),
),
ast::NestedMetaItem::MetaItem(
attr::mk_name_value_item_str(
Ident::with_empty_ctxt(sym::contents),
dummy_spanned(src_interned),
),
),
];
let include_ident = Ident::with_empty_ctxt(sym::include);
let item = attr::mk_list_item(include_ident, include_info);
items.push(ast::NestedMetaItem::MetaItem(item));
}
Err(e) => {
let lit = it
.meta_item()
.and_then(|item| item.name_value_literal())
.unwrap();
if e.kind() == ErrorKind::InvalidData {
self.cx
.struct_span_err(
lit.span,
&format!("{} wasn't a utf-8 file", filename.display()),
)
.span_label(lit.span, "contains invalid utf-8")
.emit();
} else {
let mut err = self.cx.struct_span_err(
lit.span,
&format!("couldn't read {}: {}", filename.display(), e),
);
err.span_label(lit.span, "couldn't read file");
err.emit();
}
}
}
} else {
let mut err = self.cx.struct_span_err(
it.span(),
&format!("expected path to external documentation"),
);
// Check if the user erroneously used `doc(include(...))` syntax.
let literal = it.meta_item_list().and_then(|list| {
if list.len() == 1 {
list[0].literal().map(|literal| &literal.node)
} else {
None
}
});
let (path, applicability) = match &literal {
Some(LitKind::Str(path, ..)) => {
(path.to_string(), Applicability::MachineApplicable)
}
_ => (String::from("<path>"), Applicability::HasPlaceholders),
};
err.span_suggestion(
it.span(),
"provide a file path with `=`",
format!("include = \"{}\"", path),
applicability,
);
err.emit();
}
}
let meta = attr::mk_list_item(Ident::with_empty_ctxt(sym::doc), items);
*at = attr::Attribute {
span: at.span,
id: at.id,
style: at.style,
path: meta.path,
tokens: meta.node.tokens(meta.span),
is_sugared_doc: false,
};
} else {
noop_visit_attribute(at, self)
}
}
fn visit_id(&mut self, id: &mut ast::NodeId) {
if self.monotonic {
debug_assert_eq!(*id, ast::DUMMY_NODE_ID);
*id = self.cx.resolver.next_node_id()
}
}
fn visit_fn_decl(&mut self, mut fn_decl: &mut P<ast::FnDecl>) {
self.cfg.configure_fn_decl(&mut fn_decl);
noop_visit_fn_decl(fn_decl, self);
}
}
pub struct ExpansionConfig<'feat> {
pub crate_name: String,
pub features: Option<&'feat Features>,
pub recursion_limit: usize,
pub trace_mac: bool,
pub should_test: bool, // If false, strip `#[test]` nodes
pub single_step: bool,
pub keep_macs: bool,
}
impl<'feat> ExpansionConfig<'feat> {
pub fn default(crate_name: String) -> ExpansionConfig<'static> {
ExpansionConfig {
crate_name,
features: None,
recursion_limit: 1024,
trace_mac: false,
should_test: false,
single_step: false,
keep_macs: false,
}
}
fn macros_in_extern(&self) -> bool {
self.features.map_or(false, |features| features.macros_in_extern)
}
fn proc_macro_hygiene(&self) -> bool {
self.features.map_or(false, |features| features.proc_macro_hygiene)
}
fn custom_inner_attributes(&self) -> bool {
self.features.map_or(false, |features| features.custom_inner_attributes)
}
}
// A Marker adds the given mark to the syntax context.
#[derive(Debug)]
pub struct Marker(pub ExpnId);
impl MutVisitor for Marker {
fn visit_span(&mut self, span: &mut Span) {
*span = span.apply_mark(self.0)
}
fn visit_mac(&mut self, mac: &mut ast::Mac) {
noop_visit_mac(mac, self)
}
}