From 73b50d211b254bf72ce10b5ea4c3e0033e3189f4 Mon Sep 17 00:00:00 2001 From: Aaron Hill Date: Sun, 29 Sep 2019 19:22:18 -0400 Subject: Add support for 'extern const fn' This works just as you might expect - an 'extern const fn' is a 'const fn' that is callable from foreign code. Currently, panicking is not allowed in consts. When RFC 2345 is stabilized, then panicking in an 'extern const fn' will produce a compile-time error when invoked at compile time, and an abort when invoked at runtime. Since this is extending the language (we're allowing the `const` keyword in a new context), I believe that this will need an FCP. However, it's a very minor change, so I didn't think that filing an RFC was necessary. This will allow libc (and other FFI crates) to make many functions `const`, without having to give up on making them `extern` as well. --- src/libsyntax/parse/parser.rs | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'src/libsyntax/parse/parser.rs') diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index 95f84d5cb33..6b0b60bfe47 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -1486,6 +1486,15 @@ impl<'a> Parser<'a> { Ok(()) } + /// Parses `extern` followed by an optional ABI string, or nothing. + fn parse_extern_abi(&mut self) -> PResult<'a, Abi> { + if self.eat_keyword(kw::Extern) { + Ok(self.parse_opt_abi()?.unwrap_or(Abi::C)) + } else { + Ok(Abi::Rust) + } + } + /// Parses a string as an ABI spec on an extern type or module. Consumes /// the `extern` keyword, if one is found. fn parse_opt_abi(&mut self) -> PResult<'a, Option> { -- cgit 1.4.1-3-g733a5