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Rollup merge of rust-lang#61615 - petrochenkov:errlit, r=matklad
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syntax: Treat error literals in more principled way

Free them from their character literal origins.

I actually tried to remove `LitKind::Err` entirely (by converting it into `ExprKind::Err` immediately), and it caused no diagnostic regressions in the test suite.
However, I'd still want to use error literals as general purpose error tokens some day, so I kept them.

The downside of having `LitKind::Err` in addition to `ExprKind::Err` is that every time you want to do something with `ExprKind::Err` you need to make sure that `ExprKind::Lit(LitKind::Err)` is treated in the same way.
Fortunately, this usually happens automatically because both literals and errors are "leaf" expressions, however this PR does fix a couple of inconsistencies between them.

Addresses rust-lang#60679 (comment) in a way
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Centril authored Jun 8, 2019
2 parents 2a9bcbf + 2af47fa commit 5062ad3
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Showing 11 changed files with 33 additions and 27 deletions.
3 changes: 1 addition & 2 deletions src/librustc/hir/intravisit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1020,7 +1020,6 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
ExprKind::AddrOf(_, ref subexpression) | ExprKind::Unary(_, ref subexpression) => {
visitor.visit_expr(subexpression)
}
ExprKind::Lit(_) => {}
ExprKind::Cast(ref subexpression, ref typ) | ExprKind::Type(ref subexpression, ref typ) => {
visitor.visit_expr(subexpression);
visitor.visit_ty(typ)
Expand Down Expand Up @@ -1093,7 +1092,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
ExprKind::Yield(ref subexpression) => {
visitor.visit_expr(subexpression);
}
ExprKind::Err => {}
ExprKind::Lit(_) | ExprKind::Err => {}
}
}

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4 changes: 2 additions & 2 deletions src/librustc/ich/impls_syntax.rs
Original file line number Diff line number Diff line change
Expand Up @@ -170,14 +170,14 @@ impl_stable_hash_for!(struct ::syntax::ast::Lit {

impl_stable_hash_for!(enum ::syntax::ast::LitKind {
Str(value, style),
Err(value),
ByteStr(value),
Byte(value),
Char(value),
Int(value, lit_int_type),
Float(value, float_ty),
FloatUnsuffixed(value),
Bool(value)
Bool(value),
Err(value)
});

impl_stable_hash_for_spanned!(::syntax::ast::LitKind);
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10 changes: 1 addition & 9 deletions src/librustc_mir/hair/constant.rs
Original file line number Diff line number Diff line change
Expand Up @@ -34,15 +34,6 @@ crate fn lit_to_const<'a, 'gcx, 'tcx>(
let allocation = tcx.intern_const_alloc(allocation);
ConstValue::Slice { data: allocation, start: 0, end: s.len() }
},
LitKind::Err(ref s) => {
let s = s.as_str();
let allocation = Allocation::from_byte_aligned_bytes(s.as_bytes());
let allocation = tcx.intern_const_alloc(allocation);
return Ok(tcx.mk_const(ty::Const {
val: ConstValue::Slice{ data: allocation, start: 0, end: s.len() },
ty: tcx.types.err,
}));
},
LitKind::ByteStr(ref data) => {
let id = tcx.allocate_bytes(data);
ConstValue::Scalar(Scalar::Ptr(id.into()))
Expand All @@ -66,6 +57,7 @@ crate fn lit_to_const<'a, 'gcx, 'tcx>(
}
LitKind::Bool(b) => ConstValue::Scalar(Scalar::from_bool(b)),
LitKind::Char(c) => ConstValue::Scalar(Scalar::from_char(c)),
LitKind::Err(_) => unreachable!(),
};
Ok(tcx.mk_const(ty::Const { val: lit, ty }))
}
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6 changes: 3 additions & 3 deletions src/libsyntax/ast.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1368,7 +1368,7 @@ pub enum LitKind {
FloatUnsuffixed(Symbol),
/// A boolean literal.
Bool(bool),
/// A recovered character literal that contains mutliple `char`s, most likely a typo.
/// Placeholder for a literal that wasn't well-formed in some way.
Err(Symbol),
}

Expand Down Expand Up @@ -1406,10 +1406,10 @@ impl LitKind {
| LitKind::ByteStr(..)
| LitKind::Byte(..)
| LitKind::Char(..)
| LitKind::Err(..)
| LitKind::Int(_, LitIntType::Unsuffixed)
| LitKind::FloatUnsuffixed(..)
| LitKind::Bool(..) => true,
| LitKind::Bool(..)
| LitKind::Err(..) => true,
// suffixed variants
LitKind::Int(_, LitIntType::Signed(..))
| LitKind::Int(_, LitIntType::Unsigned(..))
Expand Down
3 changes: 1 addition & 2 deletions src/libsyntax/mut_visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1101,7 +1101,6 @@ pub fn noop_visit_expr<T: MutVisitor>(Expr { node, id, span, attrs }: &mut Expr,
vis.visit_expr(rhs);
}
ExprKind::Unary(_unop, ohs) => vis.visit_expr(ohs),
ExprKind::Lit(_lit) => {}
ExprKind::Cast(expr, ty) => {
vis.visit_expr(expr);
vis.visit_ty(ty);
Expand Down Expand Up @@ -1225,7 +1224,7 @@ pub fn noop_visit_expr<T: MutVisitor>(Expr { node, id, span, attrs }: &mut Expr,
}
ExprKind::Try(expr) => vis.visit_expr(expr),
ExprKind::TryBlock(body) => vis.visit_block(body),
ExprKind::Err => {}
ExprKind::Lit(_) | ExprKind::Err => {}
}
vis.visit_id(id);
vis.visit_span(span);
Expand Down
6 changes: 5 additions & 1 deletion src/libsyntax/parse/literal.rs
Original file line number Diff line number Diff line change
Expand Up @@ -311,7 +311,11 @@ impl<'a> Parser<'a> {
let (lit, span) = (token.expect_lit(), token.span);
self.bump();
err.report(&self.sess.span_diagnostic, lit, span);
let lit = token::Lit::new(token::Err, lit.symbol, lit.suffix);
// Pack possible quotes and prefixes from the original literal into
// the error literal's symbol so they can be pretty-printed faithfully.
let suffixless_lit = token::Lit::new(lit.kind, lit.symbol, None);
let symbol = Symbol::intern(&pprust::literal_to_string(suffixless_lit));
let lit = token::Lit::new(token::Err, symbol, lit.suffix);
Lit::from_lit_token(lit, span).map_err(|_| unreachable!())
}
}
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8 changes: 4 additions & 4 deletions src/libsyntax/print/pprust.rs
Original file line number Diff line number Diff line change
Expand Up @@ -168,9 +168,6 @@ pub fn literal_to_string(lit: token::Lit) -> String {
let mut out = match kind {
token::Byte => format!("b'{}'", symbol),
token::Char => format!("'{}'", symbol),
token::Bool |
token::Float |
token::Integer => symbol.to_string(),
token::Str => format!("\"{}\"", symbol),
token::StrRaw(n) => format!("r{delim}\"{string}\"{delim}",
delim="#".repeat(n as usize),
Expand All @@ -179,7 +176,10 @@ pub fn literal_to_string(lit: token::Lit) -> String {
token::ByteStrRaw(n) => format!("br{delim}\"{string}\"{delim}",
delim="#".repeat(n as usize),
string=symbol),
token::Err => format!("'{}'", symbol),
token::Integer |
token::Float |
token::Bool |
token::Err => symbol.to_string(),
};

if let Some(suffix) = suffix {
Expand Down
3 changes: 1 addition & 2 deletions src/libsyntax/visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -714,7 +714,6 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
ExprKind::AddrOf(_, ref subexpression) | ExprKind::Unary(_, ref subexpression) => {
visitor.visit_expr(subexpression)
}
ExprKind::Lit(_) => {}
ExprKind::Cast(ref subexpression, ref typ) | ExprKind::Type(ref subexpression, ref typ) => {
visitor.visit_expr(subexpression);
visitor.visit_ty(typ)
Expand Down Expand Up @@ -826,7 +825,7 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
ExprKind::TryBlock(ref body) => {
visitor.visit_block(body)
}
ExprKind::Err => {}
ExprKind::Lit(_) | ExprKind::Err => {}
}

visitor.visit_expr_post(expression)
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4 changes: 3 additions & 1 deletion src/libsyntax_ext/concat.rs
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,6 @@ pub fn expand_syntax_ext(
match e.node {
ast::ExprKind::Lit(ref lit) => match lit.node {
ast::LitKind::Str(ref s, _)
| ast::LitKind::Err(ref s)
| ast::LitKind::Float(ref s, _)
| ast::LitKind::FloatUnsuffixed(ref s) => {
accumulator.push_str(&s.as_str());
Expand All @@ -41,6 +40,9 @@ pub fn expand_syntax_ext(
ast::LitKind::Byte(..) | ast::LitKind::ByteStr(..) => {
cx.span_err(e.span, "cannot concatenate a byte string literal");
}
ast::LitKind::Err(_) => {
has_errors = true;
}
},
ast::ExprKind::Err => {
has_errors = true;
Expand Down
5 changes: 5 additions & 0 deletions src/test/ui/extenv/issue-55897.rs
Original file line number Diff line number Diff line change
Expand Up @@ -12,4 +12,9 @@ mod nonexistent_env {
//~^ ERROR environment variable `NON_EXISTENT` not defined
}

mod erroneous_literal {
include!(concat!("NON_EXISTENT"suffix, "/data.rs"));
//~^ ERROR suffixes on a string literal are invalid
}

fn main() {}
8 changes: 7 additions & 1 deletion src/test/ui/extenv/issue-55897.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,12 @@ error: environment variable `NON_EXISTENT` not defined
LL | include!(concat!(env!("NON_EXISTENT"), "/data.rs"));
| ^^^^^^^^^^^^^^^^^^^^

error: suffixes on a string literal are invalid
--> $DIR/issue-55897.rs:16:22
|
LL | include!(concat!("NON_EXISTENT"suffix, "/data.rs"));
| ^^^^^^^^^^^^^^^^^^^^ invalid suffix `suffix`

error[E0432]: unresolved import `prelude`
--> $DIR/issue-55897.rs:1:5
|
Expand All @@ -21,6 +27,6 @@ LL | include!(concat!(env!("NON_EXISTENT"), "/data.rs"));
|
= note: import resolution is stuck, try simplifying macro imports

error: aborting due to 3 previous errors
error: aborting due to 4 previous errors

For more information about this error, try `rustc --explain E0432`.

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