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Auto merge of #41990 - qnighy:disallow-underscore-suffix-for-string-like-literals, r=nikomatsakis
Disallow underscore suffix for string-like literals. This patch turns string/bytestring/char/byte literals followed by an underscore, like `"Foo"_`, to an error. `scan_optional_raw_name` will parse `_` as a valid raw name, but it will be rejected by the parser. I also considered just stopping parsing when the suffix is `_`, but in that case `"Foo"_` will be lexed as two valid tokens. Fixes the latter half of #41723.
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commit
e862695158
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@ -480,6 +480,15 @@ impl<'a> StringReader<'a> {
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self.with_str_from(start, |string| {
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if string == "_" {
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self.sess.span_diagnostic
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.struct_span_warn(mk_sp(start, self.pos),
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"underscore literal suffix is not allowed")
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.warn("this was previously accepted by the compiler but is \
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being phased out; it will become a hard error in \
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a future release!")
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.note("for more information, see issue #42326 \
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<https://github.com/rust-lang/rust/issues/42326>")
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.emit();
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None
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} else {
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Some(Symbol::intern(string))
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@ -0,0 +1,20 @@
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// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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fn main() {
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let _ = "Foo"_;
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//~^ WARNING underscore literal suffix is not allowed
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//~| WARNING this was previously accepted
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//~| NOTE issue #42326
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}
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FAIL
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//~^ ERROR
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//~| NOTE
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