rust-lang/rust
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

Auto merge of #33706 - jseyfried:refactor_cfg, r=nrc

Browse Source 
Perform `cfg` attribute processing during macro expansion and fix bugs

This PR refactors `cfg` attribute processing and fixes bugs. More specifically:
 - It merges gated feature checking for stmt/expr attributes, `cfg_attr` processing, and `cfg` processing into a single fold.
  - This allows feature gated `cfg` variables to be used in `cfg_attr` on unconfigured items. All other feature gated attributes can already be used on unconfigured items.
 - It performs `cfg` attribute processing during macro expansion instead of after expansion so that macro-expanded items are configured the same as ordinary items. In particular, to match their non-expanded counterparts,
  - macro-expanded unconfigured macro invocations are no longer expanded,
  - macro-expanded unconfigured macro definitions are no longer usable, and
  - feature gated `cfg` variables on macro-expanded macro definitions/invocations are now errors.

This is a [breaking-change]. For example, the following would break:
```rust
macro_rules! m {
    () => {
        #[cfg(attr)]
        macro_rules! foo { () => {} }
        foo!(); // This will be an error

        macro_rules! bar { () => { fn f() {} } }
        #[cfg(attr)] bar!(); // This will no longer be expanded ...
        fn g() { f(); } // ... so that `f` will be unresolved.

        #[cfg(target_thread_local)] // This will be a gated feature error
        macro_rules! baz { () => {} }
    }
}

m!();
```

r? @nrc
This commit is contained in:
bors
2016-05-27 17:46:14 -07:00
parent 7bddce693c 53ab137841
commit 8b012ed142
8 changed files with 381 additions and 639 deletions
Download Patch File Download Diff File Expand all files Collapse all files

147
src/libsyntax/ext/expand.rs
View File

@@ -18,7 +18,8 @@ use ext::build::AstBuilder;
use attr;
use attr::{AttrMetaMethods, WithAttrs, ThinAttributesExt};
use codemap;
use codemap::{Span, Spanned, ExpnInfo, NameAndSpan, MacroBang, MacroAttribute};
use codemap::{Span, Spanned, ExpnInfo, ExpnId, NameAndSpan, MacroBang, MacroAttribute};
use config::StripUnconfigured;
use ext::base::*;
use feature_gate::{self, Features};
use fold;
@@ -33,7 +34,6 @@ use visit::Visitor;
use std_inject;
use std::collections::HashSet;
use std::env;
// A trait for AST nodes and AST node lists into which macro invocations may expand.
trait MacroGenerable: Sized {
@@ -77,25 +77,35 @@ impl_macro_generable! {
"statement", .make_stmts, lift .fold_stmt, |_span| SmallVector::zero();
}
pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
return e.and_then(|ast::Expr {id, node, span, attrs}| match node {
impl MacroGenerable for Option<P<ast::Expr>> {
fn kind_name() -> &'static str { "expression" }
fn dummy(_span: Span) -> Self { None }
fn make_with<'a>(result: Box<MacResult + 'a>) -> Option<Self> {
result.make_expr().map(Some)
}
fn fold_with<F: Folder>(self, folder: &mut F) -> Self {
self.and_then(|expr| folder.fold_opt_expr(expr))
}
}
pub fn expand_expr(expr: ast::Expr, fld: &mut MacroExpander) -> P<ast::Expr> {
match expr.node {
// expr_mac should really be expr_ext or something; it's the
// entry-point for all syntax extensions.
ast::ExprKind::Mac(mac) => {
expand_mac_invoc(mac, None, attrs.into_attr_vec(), span, fld)
expand_mac_invoc(mac, None, expr.attrs.into_attr_vec(), expr.span, fld)
}
ast::ExprKind::While(cond, body, opt_ident) => {
let cond = fld.fold_expr(cond);
let (body, opt_ident) = expand_loop_block(body, opt_ident, fld);
fld.cx.expr(span, ast::ExprKind::While(cond, body, opt_ident))
.with_attrs(fold_thin_attrs(attrs, fld))
fld.cx.expr(expr.span, ast::ExprKind::While(cond, body, opt_ident))
.with_attrs(fold_thin_attrs(expr.attrs, fld))
}
ast::ExprKind::WhileLet(pat, expr, body, opt_ident) => {
ast::ExprKind::WhileLet(pat, cond, body, opt_ident) => {
let pat = fld.fold_pat(pat);
let expr = fld.fold_expr(expr);
let cond = fld.fold_expr(cond);
// Hygienic renaming of the body.
let ((body, opt_ident), mut rewritten_pats) =
@@ -107,14 +117,14 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
});
assert!(rewritten_pats.len() == 1);
let wl = ast::ExprKind::WhileLet(rewritten_pats.remove(0), expr, body, opt_ident);
fld.cx.expr(span, wl).with_attrs(fold_thin_attrs(attrs, fld))
let wl = ast::ExprKind::WhileLet(rewritten_pats.remove(0), cond, body, opt_ident);
fld.cx.expr(expr.span, wl).with_attrs(fold_thin_attrs(expr.attrs, fld))
}
ast::ExprKind::Loop(loop_block, opt_ident) => {
let (loop_block, opt_ident) = expand_loop_block(loop_block, opt_ident, fld);
fld.cx.expr(span, ast::ExprKind::Loop(loop_block, opt_ident))
.with_attrs(fold_thin_attrs(attrs, fld))
fld.cx.expr(expr.span, ast::ExprKind::Loop(loop_block, opt_ident))
.with_attrs(fold_thin_attrs(expr.attrs, fld))
}
ast::ExprKind::ForLoop(pat, head, body, opt_ident) => {
@@ -132,7 +142,7 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
let head = fld.fold_expr(head);
let fl = ast::ExprKind::ForLoop(rewritten_pats.remove(0), head, body, opt_ident);
fld.cx.expr(span, fl).with_attrs(fold_thin_attrs(attrs, fld))
fld.cx.expr(expr.span, fl).with_attrs(fold_thin_attrs(expr.attrs, fld))
}
ast::ExprKind::IfLet(pat, sub_expr, body, else_opt) => {
@@ -151,7 +161,7 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
let else_opt = else_opt.map(|else_opt| fld.fold_expr(else_opt));
let sub_expr = fld.fold_expr(sub_expr);
let il = ast::ExprKind::IfLet(rewritten_pats.remove(0), sub_expr, body, else_opt);
fld.cx.expr(span, il).with_attrs(fold_thin_attrs(attrs, fld))
fld.cx.expr(expr.span, il).with_attrs(fold_thin_attrs(expr.attrs, fld))
}
ast::ExprKind::Closure(capture_clause, fn_decl, block, fn_decl_span) => {
@@ -160,22 +170,15 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
let new_node = ast::ExprKind::Closure(capture_clause,
rewritten_fn_decl,
rewritten_block,
fld.new_span(fn_decl_span));
P(ast::Expr{ id:id,
fn_decl_span);
P(ast::Expr{ id: expr.id,
node: new_node,
span: fld.new_span(span),
attrs: fold_thin_attrs(attrs, fld) })
span: expr.span,
attrs: fold_thin_attrs(expr.attrs, fld) })
}
_ => {
P(noop_fold_expr(ast::Expr {
id: id,
node: node,
span: span,
attrs: attrs
}, fld))
}
});
_ => P(noop_fold_expr(expr, fld)),
}
}
/// Expand a macro invocation. Returns the result of expansion.
@@ -322,8 +325,9 @@ fn expand_mac_invoc<T>(mac: ast::Mac, ident: Option<Ident>, attrs: Vec<ast::Attr
return T::dummy(span);
};
let marked = expanded.fold_with(&mut Marker { mark: mark });
let fully_expanded = marked.fold_with(fld);
let marked = expanded.fold_with(&mut Marker { mark: mark, expn_id: Some(fld.cx.backtrace()) });
let configured = marked.fold_with(&mut fld.strip_unconfigured());
let fully_expanded = configured.fold_with(fld);
fld.cx.bt_pop();
fully_expanded
}
@@ -699,12 +703,12 @@ impl<'a> Folder for PatIdentRenamer<'a> {
mtwt::apply_renames(self.renames, ident.ctxt));
let new_node =
PatKind::Ident(binding_mode,
Spanned{span: self.new_span(sp), node: new_ident},
Spanned{span: sp, node: new_ident},
sub.map(|p| self.fold_pat(p)));
ast::Pat {
id: id,
node: new_node,
span: self.new_span(span)
span: span,
}
},
_ => unreachable!()
@@ -774,7 +778,7 @@ fn expand_annotatable(a: Annotatable,
}
_ => unreachable!()
},
span: fld.new_span(ti.span)
span: ti.span,
})
}
_ => fold::noop_fold_trait_item(it.unwrap(), fld)
@@ -914,7 +918,7 @@ fn expand_impl_item(ii: ast::ImplItem, fld: &mut MacroExpander)
}
_ => unreachable!()
},
span: fld.new_span(ii.span)
span: ii.span,
}),
ast::ImplItemKind::Macro(mac) => {
expand_mac_invoc(mac, None, ii.attrs, ii.span, fld)
@@ -987,6 +991,12 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
pub fn new(cx: &'a mut ExtCtxt<'b>) -> MacroExpander<'a, 'b> {
MacroExpander { cx: cx }
}
fn strip_unconfigured(&mut self) -> StripUnconfigured {
StripUnconfigured::new(&self.cx.cfg,
&self.cx.parse_sess.span_diagnostic,
self.cx.feature_gated_cfgs)
}
}
impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
@@ -996,7 +1006,15 @@ impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
}
fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
expand_expr(expr, self)
expr.and_then(|expr| expand_expr(expr, self))
}
fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
expr.and_then(|expr| match expr.node {
ast::ExprKind::Mac(mac) =>
expand_mac_invoc(mac, None, expr.attrs.into_attr_vec(), expr.span, self),
_ => Some(expand_expr(expr, self)),
})
}
fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
@@ -1059,10 +1077,6 @@ impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
expand_type(ty, self)
}
fn new_span(&mut self, span: Span) -> Span {
new_span(self.cx, span)
}
}
impl<'a, 'b> MacroExpander<'a, 'b> {
@@ -1080,45 +1094,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
}
}
fn new_span(cx: &ExtCtxt, sp: Span) -> Span {
debug!("new_span(sp={:?})", sp);
if cx.codemap().more_specific_trace(sp.expn_id, cx.backtrace()) {
// If the span we are looking at has a backtrace that has more
// detail than our current backtrace, then we keep that
// backtrace. Honestly, I have no idea if this makes sense,
// because I have no idea why we are stripping the backtrace
// below. But the reason I made this change is because, in
// deriving, we were generating attributes with a specific
// backtrace, which was essential for `#[structural_match]` to
// be properly supported, but these backtraces were being
// stripped and replaced with a null backtrace. Sort of
// unclear why this is the case. --nmatsakis
debug!("new_span: keeping trace from {:?} because it is more specific",
sp.expn_id);
sp
} else {
// This discards information in the case of macro-defining macros.
//
// The comment above was originally added in
// b7ec2488ff2f29681fe28691d20fd2c260a9e454 in Feb 2012. I
// *THINK* the reason we are doing this is because we want to
// replace the backtrace of the macro contents with the
// backtrace that contains the macro use. But it's pretty
// unclear to me. --nmatsakis
let sp1 = Span {
lo: sp.lo,
hi: sp.hi,
expn_id: cx.backtrace(),
};
debug!("new_span({:?}) = {:?}", sp, sp1);
if sp.expn_id.into_u32() == 0 && env::var_os("NDM").is_some() {
panic!("NDM");
}
sp1
}
}
pub struct ExpansionConfig<'feat> {
pub crate_name: String,
pub features: Option<&'feat Features>,
@@ -1205,8 +1180,9 @@ pub fn expand_crate(mut cx: ExtCtxt,
// the ones defined here include:
// Marker - add a mark to a context
// A Marker adds the given mark to the syntax context
struct Marker { mark: Mrk }
// A Marker adds the given mark to the syntax context and
// sets spans' `expn_id` to the given expn_id (unless it is `None`).
struct Marker { mark: Mrk, expn_id: Option<ExpnId> }
impl Folder for Marker {
fn fold_ident(&mut self, id: Ident) -> Ident {
@@ -1219,14 +1195,21 @@ impl Folder for Marker {
tts: self.fold_tts(&node.tts),
ctxt: mtwt::apply_mark(self.mark, node.ctxt),
},
span: span,
span: self.new_span(span),
}
}
fn new_span(&mut self, mut span: Span) -> Span {
if let Some(expn_id) = self.expn_id {
span.expn_id = expn_id;
}
span
}
}
// apply a given mark to the given token trees. Used prior to expansion of a macro.
fn mark_tts(tts: &[TokenTree], m: Mrk) -> Vec<TokenTree> {
noop_fold_tts(tts, &mut Marker{mark:m})
noop_fold_tts(tts, &mut Marker{mark:m, expn_id: None})
}
/// Check that there are no macro invocations left in the AST: