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Allow unstable code to be injected by placement-in expansion.

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(Over time the stability checking has gotten more finicky; in
particular one must attach the (whole) span of the original `in PLACE
BLOCK` expression to the injected references to unstable paths, as
noted in the comments.)

call `push_compiler_expansion` during the placement-`in` expansion.
This commit is contained in:
Felix S. Klock II 2015-06-05 18:51:23 +02:00
parent cb5f0b4971
commit 07afe91fda
1 changed files with 23 additions and 3 deletions
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26
src/libsyntax/ext/expand.rs
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@ -50,12 +50,23 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
callee: NameAndSpan {
name: expansion_desc.to_string(),
format: CompilerExpansion,
// This does *not* mean code generated after
// `push_compiler_expansion` is automatically exempt
// from stability lints; must also tag such code with
// an appropriate span from `fld.cx.backtrace()`.
allow_internal_unstable: true,
span: None,
},
});
}
// Sets the expn_id so that we can use unstable methods.
fn allow_unstable(fld: &mut MacroExpander, span: Span) -> Span {
Span { expn_id: fld.cx.backtrace(), ..span }
}
let expr_span = e.span;
return e.and_then(|ast::Expr {id, node, span}| match node {
@ -101,6 +112,8 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
&fld.cx.parse_sess.span_diagnostic,
expr_span);
push_compiler_expansion(fld, expr_span, "placement-in expansion");
let value_span = value_expr.span;
let placer_span = placer.span;
@ -121,9 +134,14 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
let inplace_finalize = ["ops", "InPlace", "finalize"];
let make_call = |fld: &mut MacroExpander, p, args| {
let path = mk_core_path(fld, placer_span, p);
// We feed in the `expr_span` because codemap's span_allows_unstable
// allows the call_site span to inherit the `allow_internal_unstable`
// setting.
let span_unstable = allow_unstable(fld, expr_span);
let path = mk_core_path(fld, span_unstable, p);
let path = fld.cx.expr_path(path);
fld.cx.expr_call(span, path, args)
let expr_span_unstable = allow_unstable(fld, span);
fld.cx.expr_call(expr_span_unstable, path, args)
};
let stmt_let = |fld: &mut MacroExpander, bind, expr| {
@ -166,7 +184,9 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
};
let block = fld.cx.block_all(span, vec![s1, s2, s3], expr);
fld.cx.expr_block(block)
let result = fld.cx.expr_block(block);
fld.cx.bt_pop();
result
}
// Issue #22181: