--- /dev/null
+{
+ "git": {
+ "sha1": "758784bb05c3d68569ca5001972fe5c31b8175c5"
+ }
+}
--- /dev/null
+github: dtolnay
--- /dev/null
+name: CI
+
+on:
+ push:
+ pull_request:
+ schedule: [cron: "40 1 * * *"]
+
+jobs:
+ test:
+ name: Rust ${{matrix.rust}}
+ runs-on: ubuntu-latest
+ strategy:
+ fail-fast: false
+ matrix:
+ rust: [nightly, beta, stable, 1.45.0, 1.42.0, 1.31.0]
+ steps:
+ - uses: actions/checkout@v2
+ - uses: dtolnay/rust-toolchain@master
+ with:
+ toolchain: ${{matrix.rust}}
+ - if: matrix.rust == '1.31.0'
+ run: echo 'extern crate proc_macro;' >> demo-hack-impl/src/lib.rs
+ - run: cargo run --manifest-path example/Cargo.toml
+ - run: cargo test --all
--- /dev/null
+target
+Cargo.lock
--- /dev/null
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies
+#
+# If you believe there's an error in this file please file an
+# issue against the rust-lang/cargo repository. If you're
+# editing this file be aware that the upstream Cargo.toml
+# will likely look very different (and much more reasonable)
+
+[package]
+edition = "2018"
+name = "proc-macro-hack"
+version = "0.5.19"
+authors = ["David Tolnay <dtolnay@gmail.com>"]
+description = "Procedural macros in expression position"
+readme = "README.md"
+categories = ["development-tools::procedural-macro-helpers"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/dtolnay/proc-macro-hack"
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[lib]
+proc-macro = true
+[dev-dependencies.demo-hack]
+version = "0.0.5"
+
+[dev-dependencies.demo-hack-impl]
+version = "0.0.5"
+
+[dev-dependencies.quote]
+version = "1.0"
+
+[dev-dependencies.rustversion]
+version = "1.0"
+
+[dev-dependencies.syn]
+version = "1.0.5"
+
+[dev-dependencies.trybuild]
+version = "1.0"
--- /dev/null
+[package]
+name = "proc-macro-hack"
+version = "0.5.19"
+authors = ["David Tolnay <dtolnay@gmail.com>"]
+edition = "2018"
+license = "MIT OR Apache-2.0"
+description = "Procedural macros in expression position"
+repository = "https://github.com/dtolnay/proc-macro-hack"
+categories = ["development-tools::procedural-macro-helpers"]
+readme = "README.md"
+
+[lib]
+proc-macro = true
+
+[dev-dependencies]
+demo-hack = { version = "0.0.5", path = "demo-hack" }
+demo-hack-impl = { version = "0.0.5", path = "demo-hack-impl" }
+quote = "1.0"
+rustversion = "1.0"
+syn = "1.0.5"
+trybuild = "1.0"
+
+[workspace]
+members = ["demo-hack", "demo-hack-impl", "example", "nested"]
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
--- /dev/null
+ Apache License
+ Version 2.0, January 2004
+ http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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+5. Submission of Contributions. Unless You explicitly state otherwise,
+ any Contribution intentionally submitted for inclusion in the Work
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+ Notwithstanding the above, nothing herein shall supersede or modify
+ the terms of any separate license agreement you may have executed
+ with Licensor regarding such Contributions.
+
+6. Trademarks. This License does not grant permission to use the trade
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+
+7. Disclaimer of Warranty. Unless required by applicable law or
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+ Contributor provides its Contributions) on an "AS IS" BASIS,
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+ risks associated with Your exercise of permissions under this License.
+
+8. Limitation of Liability. In no event and under no legal theory,
+ whether in tort (including negligence), contract, or otherwise,
+ unless required by applicable law (such as deliberate and grossly
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+9. Accepting Warranty or Additional Liability. While redistributing
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+ on Your own behalf and on Your sole responsibility, not on behalf
+ of any other Contributor, and only if You agree to indemnify,
+ defend, and hold each Contributor harmless for any liability
+ incurred by, or claims asserted against, such Contributor by reason
+ of your accepting any such warranty or additional liability.
+
+END OF TERMS AND CONDITIONS
+
+APPENDIX: How to apply the Apache License to your work.
+
+ To apply the Apache License to your work, attach the following
+ boilerplate notice, with the fields enclosed by brackets "[]"
+ replaced with your own identifying information. (Don't include
+ the brackets!) The text should be enclosed in the appropriate
+ comment syntax for the file format. We also recommend that a
+ file or class name and description of purpose be included on the
+ same "printed page" as the copyright notice for easier
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+
+Copyright [yyyy] [name of copyright owner]
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
--- /dev/null
+Copyright (c) 2018 David Tolnay
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
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+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
--- /dev/null
+Procedural macros in expression position
+========================================
+
+[<img alt="github" src="https://img.shields.io/badge/github-dtolnay/proc--macro--hack-8da0cb?style=for-the-badge&labelColor=555555&logo=github" height="20">](https://github.com/dtolnay/proc-macro-hack)
+[<img alt="crates.io" src="https://img.shields.io/crates/v/proc-macro-hack.svg?style=for-the-badge&color=fc8d62&logo=rust" height="20">](https://crates.io/crates/proc-macro-hack)
+[<img alt="docs.rs" src="https://img.shields.io/badge/docs.rs-proc--macro--hack-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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" height="20">](https://docs.rs/proc-macro-hack)
+[<img alt="build status" src="https://img.shields.io/github/workflow/status/dtolnay/proc-macro-hack/CI/master?style=for-the-badge" height="20">](https://github.com/dtolnay/proc-macro-hack/actions?query=branch%3Amaster)
+
+<table><tr><td><hr>
+<b>Note:</b> <i>As of Rust 1.45 this crate is superseded by native support for
+#[proc_macro] in expression position. Only consider using this crate if you care
+about supporting compilers between 1.31 and 1.45.</i>
+<hr></td></tr></table>
+
+Since Rust 1.30, the language supports user-defined function-like procedural
+macros. However these can only be invoked in item position, not in statements or
+expressions.
+
+This crate implements an alternative type of procedural macro that can be
+invoked in statement or expression position.
+
+This approach works with any Rust version 1.31+.
+
+## Defining procedural macros
+
+Two crates are required to define a procedural macro.
+
+### The implementation crate
+
+This crate must contain nothing but procedural macros. Private helper
+functions and private modules are fine but nothing can be public.
+
+[» example of an implementation crate][demo-hack-impl]
+
+Just like you would use a #\[proc_macro\] attribute to define a natively
+supported procedural macro, use proc-macro-hack's #\[proc_macro_hack\]
+attribute to define a procedural macro that works in expression position.
+The function signature is the same as for ordinary function-like procedural
+macros.
+
+```rust
+use proc_macro::TokenStream;
+use proc_macro_hack::proc_macro_hack;
+use quote::quote;
+use syn::{parse_macro_input, Expr};
+
+#[proc_macro_hack]
+pub fn add_one(input: TokenStream) -> TokenStream {
+ let expr = parse_macro_input!(input as Expr);
+ TokenStream::from(quote! {
+ 1 + (#expr)
+ })
+}
+```
+
+### The declaration crate
+
+This crate is allowed to contain other public things if you need, for
+example traits or functions or ordinary macros.
+
+[» example of a declaration crate][demo-hack]
+
+Within the declaration crate there needs to be a re-export of your
+procedural macro from the implementation crate. The re-export also carries a
+\#\[proc_macro_hack\] attribute.
+
+```rust
+use proc_macro_hack::proc_macro_hack;
+
+/// Add one to an expression.
+///
+/// (Documentation goes here on the re-export, not in the other crate.)
+#[proc_macro_hack]
+pub use demo_hack_impl::add_one;
+```
+
+Both crates depend on `proc-macro-hack`:
+
+```toml
+[dependencies]
+proc-macro-hack = "0.5"
+```
+
+Additionally, your implementation crate (but not your declaration crate) is
+a proc macro crate:
+
+```toml
+[lib]
+proc-macro = true
+```
+
+## Using procedural macros
+
+Users of your crate depend on your declaration crate (not your
+implementation crate), then use your procedural macros as usual.
+
+[» example of a downstream crate][example]
+
+```rust
+use demo_hack::add_one;
+
+fn main() {
+ let two = 2;
+ let nine = add_one!(two) + add_one!(2 + 3);
+ println!("nine = {}", nine);
+}
+```
+
+[demo-hack-impl]: https://github.com/dtolnay/proc-macro-hack/tree/master/demo-hack-impl
+[demo-hack]: https://github.com/dtolnay/proc-macro-hack/tree/master/demo-hack
+[example]: https://github.com/dtolnay/proc-macro-hack/tree/master/example
+
+## Limitations
+
+- Only proc macros in expression position are supported. Proc macros in pattern
+ position ([#20]) are not supported.
+
+- By default, nested invocations are not supported i.e. the code emitted by a
+ proc-macro-hack macro invocation cannot contain recursive calls to the same
+ proc-macro-hack macro nor calls to any other proc-macro-hack macros. Use
+ [`proc-macro-nested`] if you require support for nested invocations.
+
+- By default, hygiene is structured such that the expanded code can't refer to
+ local variables other than those passed by name somewhere in the macro input.
+ If your macro must refer to *local* variables that don't get named in the
+ macro input, use `#[proc_macro_hack(fake_call_site)]` on the re-export in your
+ declaration crate. *Most macros won't need this.*
+
+- On compilers that are new enough to natively support proc macros in expression
+ position, proc-macro-hack does not automatically use that support, since the
+ hygiene can be subtly different between the two implementations. To opt in to
+ compiling your macro to native `#[proc_macro]` on sufficiently new compilers,
+ use `#[proc_macro_hack(only_hack_old_rustc)]` on the re-export in your
+ declaration crate.
+
+[#10]: https://github.com/dtolnay/proc-macro-hack/issues/10
+[#20]: https://github.com/dtolnay/proc-macro-hack/issues/20
+[`proc-macro-nested`]: https://docs.rs/proc-macro-nested
+
+<br>
+
+#### License
+
+<sup>
+Licensed under either of <a href="LICENSE-APACHE">Apache License, Version
+2.0</a> or <a href="LICENSE-MIT">MIT license</a> at your option.
+</sup>
+
+<br>
+
+<sub>
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in this hack by you, as defined in the Apache-2.0 license, shall
+be dual licensed as above, without any additional terms or conditions.
+</sub>
--- /dev/null
+use std::env;
+use std::process::Command;
+use std::str;
+
+// The rustc-cfg strings below are *not* public API. Please let us know by
+// opening a GitHub issue if your build environment requires some way to enable
+// these cfgs other than by executing our build script.
+fn main() {
+ let minor = match rustc_minor_version() {
+ Some(minor) => minor,
+ None => return,
+ };
+
+ // Function-like procedural macros in expressions, patterns, and statements
+ // stabilized in Rust 1.45:
+ // https://blog.rust-lang.org/2020/07/16/Rust-1.45.0.html#stabilizing-function-like-procedural-macros-in-expressions-patterns-and-statements
+ if minor < 45 {
+ println!("cargo:rustc-cfg=need_proc_macro_hack");
+ }
+}
+
+fn rustc_minor_version() -> Option<u32> {
+ let rustc = env::var_os("RUSTC")?;
+ let output = Command::new(rustc).arg("--version").output().ok()?;
+ let version = str::from_utf8(&output.stdout).ok()?;
+ let mut pieces = version.split('.');
+ if pieces.next() != Some("rustc 1") {
+ return None;
+ }
+ pieces.next()?.parse().ok()
+}
--- /dev/null
+use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
+use std::iter::FromIterator;
+
+pub struct Error {
+ span: Span,
+ msg: String,
+}
+
+impl Error {
+ pub fn new(span: Span, msg: impl Into<String>) -> Self {
+ Error {
+ span,
+ msg: msg.into(),
+ }
+ }
+}
+
+pub fn compile_error(err: Error) -> TokenStream {
+ // compile_error!($msg)
+ TokenStream::from_iter(vec![
+ TokenTree::Ident(Ident::new("compile_error", err.span)),
+ TokenTree::Punct({
+ let mut punct = Punct::new('!', Spacing::Alone);
+ punct.set_span(err.span);
+ punct
+ }),
+ TokenTree::Group({
+ let mut group = Group::new(Delimiter::Brace, {
+ TokenStream::from_iter(vec![TokenTree::Literal({
+ let mut string = Literal::string(&err.msg);
+ string.set_span(err.span);
+ string
+ })])
+ });
+ group.set_span(err.span);
+ group
+ }),
+ ])
+}
--- /dev/null
+use proc_macro::{token_stream, Delimiter, TokenStream, TokenTree};
+
+pub type Iter<'a> = &'a mut IterImpl;
+
+pub struct IterImpl {
+ stack: Vec<token_stream::IntoIter>,
+ peeked: Option<TokenTree>,
+}
+
+pub fn new(tokens: TokenStream) -> IterImpl {
+ IterImpl {
+ stack: vec![tokens.into_iter()],
+ peeked: None,
+ }
+}
+
+impl IterImpl {
+ pub fn peek(&mut self) -> Option<&TokenTree> {
+ self.peeked = self.next();
+ self.peeked.as_ref()
+ }
+}
+
+impl Iterator for IterImpl {
+ type Item = TokenTree;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if let Some(tt) = self.peeked.take() {
+ return Some(tt);
+ }
+ loop {
+ let top = self.stack.last_mut()?;
+ match top.next() {
+ None => drop(self.stack.pop()),
+ Some(TokenTree::Group(ref group)) if group.delimiter() == Delimiter::None => {
+ self.stack.push(group.stream().into_iter());
+ }
+ Some(tt) => return Some(tt),
+ }
+ }
+ }
+}
--- /dev/null
+//! [![github]](https://github.com/dtolnay/proc-macro-hack) [![crates-io]](https://crates.io/crates/proc-macro-hack) [![docs-rs]](https://docs.rs/proc-macro-hack)
+//!
+//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
+//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
+//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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
+//!
+//! <br>
+//!
+//! <table><tr><td><hr>
+//! <b>Note:</b> <i>As of Rust 1.45 this crate is superseded by native support
+//! for #[proc_macro] in expression position. Only consider using this crate if
+//! you care about supporting compilers between 1.31 and 1.45.</i>
+//! <hr></td></tr></table>
+//!
+//! Since Rust 1.30, the language supports user-defined function-like procedural
+//! macros. However these can only be invoked in item position, not in
+//! statements or expressions.
+//!
+//! This crate implements an alternative type of procedural macro that can be
+//! invoked in statement or expression position.
+//!
+//! # Defining procedural macros
+//!
+//! Two crates are required to define a procedural macro.
+//!
+//! ## The implementation crate
+//!
+//! This crate must contain nothing but procedural macros. Private helper
+//! functions and private modules are fine but nothing can be public.
+//!
+//! [» example of an implementation crate][demo-hack-impl]
+//!
+//! Just like you would use a #\[proc_macro\] attribute to define a natively
+//! supported procedural macro, use proc-macro-hack's #\[proc_macro_hack\]
+//! attribute to define a procedural macro that works in expression position.
+//! The function signature is the same as for ordinary function-like procedural
+//! macros.
+//!
+//! ```
+//! # extern crate proc_macro;
+//! #
+//! use proc_macro::TokenStream;
+//! use proc_macro_hack::proc_macro_hack;
+//! use quote::quote;
+//! use syn::{parse_macro_input, Expr};
+//!
+//! # const IGNORE: &str = stringify! {
+//! #[proc_macro_hack]
+//! # };
+//! pub fn add_one(input: TokenStream) -> TokenStream {
+//! let expr = parse_macro_input!(input as Expr);
+//! TokenStream::from(quote! {
+//! 1 + (#expr)
+//! })
+//! }
+//! #
+//! # fn main() {}
+//! ```
+//!
+//! ## The declaration crate
+//!
+//! This crate is allowed to contain other public things if you need, for
+//! example traits or functions or ordinary macros.
+//!
+//! [» example of a declaration crate][demo-hack]
+//!
+//! Within the declaration crate there needs to be a re-export of your
+//! procedural macro from the implementation crate. The re-export also carries a
+//! \#\[proc_macro_hack\] attribute.
+//!
+//! ```
+//! use proc_macro_hack::proc_macro_hack;
+//!
+//! /// Add one to an expression.
+//! ///
+//! /// (Documentation goes here on the re-export, not in the other crate.)
+//! #[proc_macro_hack]
+//! pub use demo_hack_impl::add_one;
+//! #
+//! # fn main() {}
+//! ```
+//!
+//! Both crates depend on `proc-macro-hack`:
+//!
+//! ```toml
+//! [dependencies]
+//! proc-macro-hack = "0.5"
+//! ```
+//!
+//! Additionally, your implementation crate (but not your declaration crate) is
+//! a proc macro crate:
+//!
+//! ```toml
+//! [lib]
+//! proc-macro = true
+//! ```
+//!
+//! # Using procedural macros
+//!
+//! Users of your crate depend on your declaration crate (not your
+//! implementation crate), then use your procedural macros as usual.
+//!
+//! [» example of a downstream crate][example]
+//!
+//! ```
+//! use demo_hack::add_one;
+//!
+//! fn main() {
+//! let two = 2;
+//! let nine = add_one!(two) + add_one!(2 + 3);
+//! println!("nine = {}", nine);
+//! }
+//! ```
+//!
+//! [demo-hack-impl]: https://github.com/dtolnay/proc-macro-hack/tree/master/demo-hack-impl
+//! [demo-hack]: https://github.com/dtolnay/proc-macro-hack/tree/master/demo-hack
+//! [example]: https://github.com/dtolnay/proc-macro-hack/tree/master/example
+//!
+//! # Limitations
+//!
+//! - Only proc macros in expression position are supported. Proc macros in
+//! pattern position ([#20]) are not supported.
+//!
+//! - By default, nested invocations are not supported i.e. the code emitted by
+//! a proc-macro-hack macro invocation cannot contain recursive calls to the
+//! same proc-macro-hack macro nor calls to any other proc-macro-hack macros.
+//! Use [`proc-macro-nested`] if you require support for nested invocations.
+//!
+//! - By default, hygiene is structured such that the expanded code can't refer
+//! to local variables other than those passed by name somewhere in the macro
+//! input. If your macro must refer to *local* variables that don't get named
+//! in the macro input, use `#[proc_macro_hack(fake_call_site)]` on the
+//! re-export in your declaration crate. *Most macros won't need this.*
+//!
+//! - On compilers that are new enough to natively support proc macros in
+//! expression position, proc-macro-hack does not automatically use that
+//! support, since the hygiene can be subtly different between the two
+//! implementations. To opt in to compiling your macro to native
+//! `#[proc_macro]` on sufficiently new compilers, use
+//! `#[proc_macro_hack(only_hack_old_rustc)]` on the re-export in your
+//! declaration crate.
+//!
+//! [#10]: https://github.com/dtolnay/proc-macro-hack/issues/10
+//! [#20]: https://github.com/dtolnay/proc-macro-hack/issues/20
+//! [`proc-macro-nested`]: https://docs.rs/proc-macro-nested
+
+#![recursion_limit = "512"]
+#![allow(clippy::needless_doctest_main, clippy::toplevel_ref_arg)]
+
+extern crate proc_macro;
+
+#[macro_use]
+mod quote;
+
+mod error;
+mod iter;
+mod parse;
+
+use crate::error::{compile_error, Error};
+use crate::iter::Iter;
+use crate::parse::{
+ parse_define_args, parse_enum_hack, parse_export_args, parse_fake_call_site, parse_input,
+};
+use proc_macro::{Ident, Punct, Spacing, Span, TokenStream, TokenTree};
+use std::fmt::Write;
+
+type Visibility = Option<Ident>;
+
+enum Input {
+ Export(Export),
+ Define(Define),
+}
+
+// pub use demo_hack_impl::{m1, m2 as qrst};
+struct Export {
+ attrs: TokenStream,
+ vis: Visibility,
+ from: Ident,
+ macros: Vec<Macro>,
+}
+
+// pub fn m1(input: TokenStream) -> TokenStream { ... }
+struct Define {
+ attrs: TokenStream,
+ name: Ident,
+ body: TokenStream,
+}
+
+struct Macro {
+ name: Ident,
+ export_as: Ident,
+}
+
+#[proc_macro_attribute]
+pub fn proc_macro_hack(args: TokenStream, input: TokenStream) -> TokenStream {
+ let ref mut args = iter::new(args);
+ let ref mut input = iter::new(input);
+ expand_proc_macro_hack(args, input).unwrap_or_else(compile_error)
+}
+
+fn expand_proc_macro_hack(args: Iter, input: Iter) -> Result<TokenStream, Error> {
+ match parse_input(input)? {
+ Input::Export(export) => {
+ let args = parse_export_args(args)?;
+ Ok(expand_export(export, args))
+ }
+ Input::Define(define) => {
+ parse_define_args(args)?;
+ Ok(expand_define(define))
+ }
+ }
+}
+
+#[doc(hidden)]
+#[proc_macro_derive(ProcMacroHack)]
+pub fn enum_hack(input: TokenStream) -> TokenStream {
+ let ref mut input = iter::new(input);
+ parse_enum_hack(input).unwrap_or_else(compile_error)
+}
+
+struct FakeCallSite {
+ derive: Ident,
+ rest: TokenStream,
+}
+
+#[doc(hidden)]
+#[proc_macro_attribute]
+pub fn fake_call_site(args: TokenStream, input: TokenStream) -> TokenStream {
+ let ref mut args = iter::new(args);
+ let ref mut input = iter::new(input);
+ expand_fake_call_site(args, input).unwrap_or_else(compile_error)
+}
+
+fn expand_fake_call_site(args: Iter, input: Iter) -> Result<TokenStream, Error> {
+ let span = match args.next() {
+ Some(token) => token.span(),
+ None => return Ok(input.collect()),
+ };
+
+ let input = parse_fake_call_site(input)?;
+ let mut derive = input.derive;
+ derive.set_span(span);
+ let rest = input.rest;
+
+ Ok(quote! {
+ #[derive(#derive)]
+ #rest
+ })
+}
+
+struct ExportArgs {
+ support_nested: bool,
+ internal_macro_calls: u16,
+ fake_call_site: bool,
+ only_hack_old_rustc: bool,
+}
+
+fn expand_export(export: Export, args: ExportArgs) -> TokenStream {
+ if args.only_hack_old_rustc && cfg!(not(need_proc_macro_hack)) {
+ return expand_export_nohack(export);
+ }
+
+ let dummy = dummy_name_for_export(&export);
+
+ let attrs = export.attrs;
+ let vis = export.vis;
+ let macro_export = match vis {
+ Some(_) => quote!(#[macro_export]),
+ None => quote!(),
+ };
+ let crate_prefix = vis.as_ref().map(|_| quote!($crate::));
+ let enum_variant = if args.support_nested {
+ if args.internal_macro_calls == 0 {
+ Ident::new("Nested", Span::call_site())
+ } else {
+ let name = format!("Nested{}", args.internal_macro_calls);
+ Ident::new(&name, Span::call_site())
+ }
+ } else {
+ Ident::new("Value", Span::call_site())
+ };
+
+ let from = export.from;
+ let mut actual_names = TokenStream::new();
+ let mut export_dispatch = TokenStream::new();
+ let mut export_call_site = TokenStream::new();
+ let mut macro_rules = TokenStream::new();
+ for Macro { name, export_as } in &export.macros {
+ let hacked = hacked_proc_macro_name(&name);
+ let dispatch = dispatch_macro_name(&name);
+ let call_site = call_site_macro_name(&name);
+
+ if !actual_names.is_empty() {
+ actual_names.extend(quote!(,));
+ }
+ actual_names.extend(quote!(#hacked));
+
+ if !export_dispatch.is_empty() {
+ export_dispatch.extend(quote!(,));
+ }
+ export_dispatch.extend(quote!(dispatch as #dispatch));
+
+ if !export_call_site.is_empty() {
+ export_call_site.extend(quote!(,));
+ }
+ export_call_site.extend(quote!(fake_call_site as #call_site));
+
+ let do_derive = if !args.fake_call_site {
+ quote! {
+ #[derive(#crate_prefix #hacked)]
+ }
+ } else if crate_prefix.is_some() {
+ quote! {
+ use #crate_prefix #hacked;
+ #[#crate_prefix #call_site ($($proc_macro)*)]
+ #[derive(#hacked)]
+ }
+ } else {
+ quote! {
+ #[#call_site ($($proc_macro)*)]
+ #[derive(#hacked)]
+ }
+ };
+
+ let proc_macro_call = if args.support_nested {
+ let extra_bangs = (0..args.internal_macro_calls)
+ .map(|_| TokenTree::Punct(Punct::new('!', Spacing::Alone)))
+ .collect::<TokenStream>();
+ quote! {
+ #crate_prefix #dispatch! { ($($proc_macro)*) #extra_bangs }
+ }
+ } else {
+ quote! {
+ proc_macro_call!()
+ }
+ };
+
+ macro_rules.extend(quote! {
+ #attrs
+ #macro_export
+ macro_rules! #export_as {
+ ($($proc_macro:tt)*) => {{
+ #do_derive
+ #[allow(dead_code)]
+ enum ProcMacroHack {
+ #enum_variant = (stringify! { $($proc_macro)* }, 0).1,
+ }
+ #proc_macro_call
+ }};
+ }
+ });
+ }
+
+ if export.macros.len() != 1 {
+ export_dispatch = quote!({#export_dispatch});
+ export_call_site = quote!({#export_call_site});
+ actual_names = quote!({#actual_names});
+ }
+
+ let export_dispatch = if args.support_nested {
+ quote! {
+ #[doc(hidden)]
+ #vis use proc_macro_nested::#export_dispatch;
+ }
+ } else {
+ quote!()
+ };
+
+ let export_call_site = if args.fake_call_site {
+ quote! {
+ #[doc(hidden)]
+ #vis use proc_macro_hack::#export_call_site;
+ }
+ } else {
+ quote!()
+ };
+
+ let expanded = quote! {
+ #[doc(hidden)]
+ #vis use #from::#actual_names;
+
+ #export_dispatch
+ #export_call_site
+
+ #macro_rules
+ };
+
+ wrap_in_enum_hack(dummy, expanded)
+}
+
+fn expand_export_nohack(export: Export) -> TokenStream {
+ let attrs = export.attrs;
+ let vis = export.vis;
+ let from = export.from;
+ let mut names = TokenStream::new();
+
+ for Macro { name, export_as } in &export.macros {
+ let pub_name = pub_proc_macro_name(&name);
+ if !names.is_empty() {
+ names.extend(quote!(,));
+ }
+ names.extend(quote!(#pub_name as #export_as));
+ }
+
+ if export.macros.len() != 1 {
+ names = quote!({#names});
+ }
+
+ quote! {
+ #attrs
+ #vis use #from::#names;
+ }
+}
+
+fn expand_define(define: Define) -> TokenStream {
+ let attrs = define.attrs;
+ let name = define.name;
+ let pub_name = pub_proc_macro_name(&name);
+ let hacked = hacked_proc_macro_name(&name);
+ let body = define.body;
+
+ quote! {
+ mod #pub_name {
+ extern crate proc_macro;
+ pub use self::proc_macro::*;
+ }
+
+ #attrs
+ #[doc(hidden)]
+ #[proc_macro_derive(#hacked)]
+ pub fn #hacked(input: #pub_name::TokenStream) -> #pub_name::TokenStream {
+ use std::iter::FromIterator;
+
+ let mut iter = input.into_iter();
+ iter.next().unwrap(); // `enum`
+ iter.next().unwrap(); // `ProcMacroHack`
+ iter.next().unwrap(); // `#`
+ iter.next().unwrap(); // `[allow(dead_code)]`
+
+ let mut braces = match iter.next().unwrap() {
+ #pub_name::TokenTree::Group(group) => group.stream().into_iter(),
+ _ => unimplemented!(),
+ };
+ let variant = braces.next().unwrap(); // `Value` or `Nested`
+ let varname = variant.to_string();
+ let support_nested = varname.starts_with("Nested");
+ braces.next().unwrap(); // `=`
+
+ let mut parens = match braces.next().unwrap() {
+ #pub_name::TokenTree::Group(group) => group.stream().into_iter(),
+ _ => unimplemented!(),
+ };
+ parens.next().unwrap(); // `stringify`
+ parens.next().unwrap(); // `!`
+
+ let inner = match parens.next().unwrap() {
+ #pub_name::TokenTree::Group(group) => group.stream(),
+ _ => unimplemented!(),
+ };
+
+ let output: #pub_name::TokenStream = #name(inner.clone());
+
+ fn count_bangs(input: #pub_name::TokenStream) -> usize {
+ let mut count = 0;
+ for token in input {
+ match token {
+ #pub_name::TokenTree::Punct(punct) => {
+ if punct.as_char() == '!' {
+ count += 1;
+ }
+ }
+ #pub_name::TokenTree::Group(group) => {
+ count += count_bangs(group.stream());
+ }
+ _ => {}
+ }
+ }
+ count
+ }
+
+ // macro_rules! proc_macro_call {
+ // () => { #output }
+ // }
+ #pub_name::TokenStream::from_iter(vec![
+ #pub_name::TokenTree::Ident(
+ #pub_name::Ident::new("macro_rules", #pub_name::Span::call_site()),
+ ),
+ #pub_name::TokenTree::Punct(
+ #pub_name::Punct::new('!', #pub_name::Spacing::Alone),
+ ),
+ #pub_name::TokenTree::Ident(
+ #pub_name::Ident::new(
+ &if support_nested {
+ let extra_bangs = if varname == "Nested" {
+ 0
+ } else {
+ varname["Nested".len()..].parse().unwrap()
+ };
+ format!("proc_macro_call_{}", extra_bangs + count_bangs(inner))
+ } else {
+ String::from("proc_macro_call")
+ },
+ #pub_name::Span::call_site(),
+ ),
+ ),
+ #pub_name::TokenTree::Group(
+ #pub_name::Group::new(#pub_name::Delimiter::Brace, #pub_name::TokenStream::from_iter(vec![
+ #pub_name::TokenTree::Group(
+ #pub_name::Group::new(#pub_name::Delimiter::Parenthesis, #pub_name::TokenStream::new()),
+ ),
+ #pub_name::TokenTree::Punct(
+ #pub_name::Punct::new('=', #pub_name::Spacing::Joint),
+ ),
+ #pub_name::TokenTree::Punct(
+ #pub_name::Punct::new('>', #pub_name::Spacing::Alone),
+ ),
+ #pub_name::TokenTree::Group(
+ #pub_name::Group::new(#pub_name::Delimiter::Brace, output),
+ ),
+ ])),
+ ),
+ ])
+ }
+
+ #attrs
+ #[proc_macro]
+ pub fn #pub_name(input: #pub_name::TokenStream) -> #pub_name::TokenStream {
+ #name(input)
+ }
+
+ fn #name #body
+ }
+}
+
+fn pub_proc_macro_name(conceptual: &Ident) -> Ident {
+ Ident::new(
+ &format!("proc_macro_hack_{}", conceptual),
+ conceptual.span(),
+ )
+}
+
+fn hacked_proc_macro_name(conceptual: &Ident) -> Ident {
+ Ident::new(
+ &format!("_proc_macro_hack_{}", conceptual),
+ conceptual.span(),
+ )
+}
+
+fn dispatch_macro_name(conceptual: &Ident) -> Ident {
+ Ident::new(
+ &format!("proc_macro_call_{}", conceptual),
+ conceptual.span(),
+ )
+}
+
+fn call_site_macro_name(conceptual: &Ident) -> Ident {
+ Ident::new(
+ &format!("proc_macro_fake_call_site_{}", conceptual),
+ conceptual.span(),
+ )
+}
+
+fn dummy_name_for_export(export: &Export) -> String {
+ let mut dummy = String::new();
+ let from = unraw(&export.from).to_string();
+ write!(dummy, "_{}{}", from.len(), from).unwrap();
+ for m in &export.macros {
+ let name = unraw(&m.name).to_string();
+ write!(dummy, "_{}{}", name.len(), name).unwrap();
+ }
+ dummy
+}
+
+fn unraw(ident: &Ident) -> Ident {
+ let string = ident.to_string();
+ if string.starts_with("r#") {
+ Ident::new(&string[2..], ident.span())
+ } else {
+ ident.clone()
+ }
+}
+
+fn wrap_in_enum_hack(dummy: String, inner: TokenStream) -> TokenStream {
+ let dummy = Ident::new(&dummy, Span::call_site());
+ quote! {
+ #[derive(proc_macro_hack::ProcMacroHack)]
+ enum #dummy {
+ Value = (stringify! { #inner }, 0).1,
+ }
+ }
+}
--- /dev/null
+use crate::iter::{self, Iter, IterImpl};
+use crate::{Define, Error, Export, ExportArgs, FakeCallSite, Input, Macro, Visibility};
+use proc_macro::Delimiter::{Brace, Bracket, Parenthesis};
+use proc_macro::{Delimiter, Ident, Span, TokenStream, TokenTree};
+
+pub(crate) fn parse_input(tokens: Iter) -> Result<Input, Error> {
+ let attrs = parse_attributes(tokens)?;
+ let vis = parse_visibility(tokens)?;
+ let kw = parse_ident(tokens)?;
+ if kw.to_string() == "use" {
+ parse_export(attrs, vis, tokens).map(Input::Export)
+ } else if kw.to_string() == "fn" {
+ parse_define(attrs, vis, kw.span(), tokens).map(Input::Define)
+ } else {
+ Err(Error::new(
+ kw.span(),
+ "unexpected input to #[proc_macro_hack]",
+ ))
+ }
+}
+
+fn parse_export(attrs: TokenStream, vis: Visibility, tokens: Iter) -> Result<Export, Error> {
+ let _ = parse_punct(tokens, ':');
+ let _ = parse_punct(tokens, ':');
+ let from = parse_ident(tokens)?;
+ parse_punct(tokens, ':')?;
+ parse_punct(tokens, ':')?;
+
+ let mut macros = Vec::new();
+ match tokens.peek() {
+ Some(TokenTree::Group(group)) if group.delimiter() == Brace => {
+ let ref mut content = iter::new(group.stream());
+ loop {
+ macros.push(parse_macro(content)?);
+ if content.peek().is_none() {
+ break;
+ }
+ parse_punct(content, ',')?;
+ if content.peek().is_none() {
+ break;
+ }
+ }
+ tokens.next().unwrap();
+ }
+ _ => macros.push(parse_macro(tokens)?),
+ }
+
+ parse_punct(tokens, ';')?;
+ Ok(Export {
+ attrs,
+ vis,
+ from,
+ macros,
+ })
+}
+
+fn parse_punct(tokens: Iter, ch: char) -> Result<(), Error> {
+ match tokens.peek() {
+ Some(TokenTree::Punct(punct)) if punct.as_char() == ch => {
+ tokens.next().unwrap();
+ Ok(())
+ }
+ tt => Err(Error::new(
+ tt.map_or_else(Span::call_site, TokenTree::span),
+ format!("expected `{}`", ch),
+ )),
+ }
+}
+
+fn parse_define(
+ attrs: TokenStream,
+ vis: Visibility,
+ fn_token: Span,
+ tokens: Iter,
+) -> Result<Define, Error> {
+ if vis.is_none() {
+ return Err(Error::new(
+ fn_token,
+ "functions tagged with `#[proc_macro_hack]` must be `pub`",
+ ));
+ }
+ let name = parse_ident(tokens)?;
+ let body = tokens.collect();
+ Ok(Define { attrs, name, body })
+}
+
+fn parse_macro(tokens: Iter) -> Result<Macro, Error> {
+ let name = parse_ident(tokens)?;
+ let export_as = match tokens.peek() {
+ Some(TokenTree::Ident(ident)) if ident.to_string() == "as" => {
+ tokens.next().unwrap();
+ parse_ident(tokens)?
+ }
+ _ => name.clone(),
+ };
+ Ok(Macro { name, export_as })
+}
+
+fn parse_ident(tokens: Iter) -> Result<Ident, Error> {
+ match tokens.next() {
+ Some(TokenTree::Ident(ident)) => Ok(ident),
+ tt => Err(Error::new(
+ tt.as_ref().map_or_else(Span::call_site, TokenTree::span),
+ "expected identifier",
+ )),
+ }
+}
+
+fn parse_keyword(tokens: Iter, kw: &'static str) -> Result<(), Error> {
+ match &tokens.next() {
+ Some(TokenTree::Ident(ident)) if ident.to_string() == kw => Ok(()),
+ tt => Err(Error::new(
+ tt.as_ref().map_or_else(Span::call_site, TokenTree::span),
+ format!("expected `{}`", kw),
+ )),
+ }
+}
+
+fn parse_int(tokens: Iter) -> Result<u16, Span> {
+ match tokens.next() {
+ Some(TokenTree::Literal(lit)) => lit.to_string().parse().map_err(|_| lit.span()),
+ Some(tt) => Err(tt.span()),
+ None => Err(Span::call_site()),
+ }
+}
+
+fn parse_group(tokens: Iter, delimiter: Delimiter) -> Result<IterImpl, Error> {
+ match &tokens.next() {
+ Some(TokenTree::Group(group)) if group.delimiter() == delimiter => {
+ Ok(iter::new(group.stream()))
+ }
+ tt => Err(Error::new(
+ tt.as_ref().map_or_else(Span::call_site, TokenTree::span),
+ "expected delimiter",
+ )),
+ }
+}
+
+fn parse_visibility(tokens: Iter) -> Result<Visibility, Error> {
+ if let Some(TokenTree::Ident(ident)) = tokens.peek() {
+ if ident.to_string() == "pub" {
+ match tokens.next().unwrap() {
+ TokenTree::Ident(vis) => return Ok(Some(vis)),
+ _ => unreachable!(),
+ }
+ }
+ }
+ Ok(None)
+}
+
+fn parse_attributes(tokens: Iter) -> Result<TokenStream, Error> {
+ let mut attrs = TokenStream::new();
+ while let Some(TokenTree::Punct(punct)) = tokens.peek() {
+ if punct.as_char() != '#' {
+ break;
+ }
+ let span = punct.span();
+ attrs.extend(tokens.next());
+ match tokens.peek() {
+ Some(TokenTree::Group(group)) if group.delimiter() == Bracket => {
+ attrs.extend(tokens.next());
+ }
+ _ => return Err(Error::new(span, "unexpected input")),
+ }
+ }
+ Ok(attrs)
+}
+
+pub(crate) fn parse_export_args(tokens: Iter) -> Result<ExportArgs, Error> {
+ let mut args = ExportArgs {
+ support_nested: false,
+ internal_macro_calls: 0,
+ fake_call_site: false,
+ only_hack_old_rustc: false,
+ };
+
+ while let Some(tt) = tokens.next() {
+ match &tt {
+ TokenTree::Ident(ident) if ident.to_string() == "support_nested" => {
+ args.support_nested = true;
+ }
+ TokenTree::Ident(ident) if ident.to_string() == "internal_macro_calls" => {
+ parse_punct(tokens, '=')?;
+ let calls = parse_int(tokens).map_err(|span| {
+ Error::new(span, "expected integer value for internal_macro_calls")
+ })?;
+ args.internal_macro_calls = calls;
+ }
+ TokenTree::Ident(ident) if ident.to_string() == "fake_call_site" => {
+ args.fake_call_site = true;
+ }
+ TokenTree::Ident(ident) if ident.to_string() == "only_hack_old_rustc" => {
+ args.only_hack_old_rustc = true;
+ }
+ _ => {
+ return Err(Error::new(
+ tt.span(),
+ "expected one of: `support_nested`, `internal_macro_calls`, `fake_call_site`, `only_hack_old_rustc`",
+ ));
+ }
+ }
+ if tokens.peek().is_none() {
+ break;
+ }
+ parse_punct(tokens, ',')?;
+ }
+
+ Ok(args)
+}
+
+pub(crate) fn parse_define_args(tokens: Iter) -> Result<(), Error> {
+ match tokens.peek() {
+ None => Ok(()),
+ Some(token) => Err(Error::new(
+ token.span(),
+ "unexpected argument to proc_macro_hack macro implementation; args are only accepted on the macro declaration (the `pub use`)",
+ )),
+ }
+}
+
+pub(crate) fn parse_enum_hack(tokens: Iter) -> Result<TokenStream, Error> {
+ parse_keyword(tokens, "enum")?;
+ parse_ident(tokens)?;
+
+ let ref mut braces = parse_group(tokens, Brace)?;
+ parse_ident(braces)?;
+ parse_punct(braces, '=')?;
+
+ let ref mut parens = parse_group(braces, Parenthesis)?;
+ parse_ident(parens)?;
+ parse_punct(parens, '!')?;
+
+ let ref mut inner = parse_group(parens, Brace)?;
+ let token_stream = inner.collect();
+
+ parse_punct(parens, ',')?;
+ let _ = parens.next();
+ parse_punct(braces, '.')?;
+ let _ = braces.next();
+ parse_punct(braces, ',')?;
+
+ Ok(token_stream)
+}
+
+pub(crate) fn parse_fake_call_site(tokens: Iter) -> Result<FakeCallSite, Error> {
+ parse_punct(tokens, '#')?;
+ let ref mut attr = parse_group(tokens, Bracket)?;
+ parse_keyword(attr, "derive")?;
+ let ref mut path = parse_group(attr, Parenthesis)?;
+ Ok(FakeCallSite {
+ derive: parse_ident(path)?,
+ rest: tokens.collect(),
+ })
+}
--- /dev/null
+use proc_macro::{Ident, TokenStream, TokenTree};
+use std::iter;
+
+macro_rules! quote {
+ () => {
+ ::proc_macro::TokenStream::new()
+ };
+ ($($tt:tt)*) => {{
+ let mut tokens = ::proc_macro::TokenStream::new();
+ quote_each_token!(tokens $($tt)*);
+ tokens
+ }};
+}
+
+macro_rules! quote_each_token {
+ ($tokens:ident # $var:ident $($rest:tt)*) => {
+ $crate::quote::Tokens::extend(&mut $tokens, &$var);
+ quote_each_token!($tokens $($rest)*);
+ };
+ ($tokens:ident $ident:ident $($rest:tt)*) => {
+ <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+ &mut $tokens,
+ ::std::iter::once(
+ ::proc_macro::TokenTree::Ident(
+ ::proc_macro::Ident::new(
+ stringify!($ident),
+ ::proc_macro::Span::call_site(),
+ ),
+ ),
+ ),
+ );
+ quote_each_token!($tokens $($rest)*);
+ };
+ ($tokens:ident ( $($inner:tt)* ) $($rest:tt)*) => {
+ <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+ &mut $tokens,
+ ::std::iter::once(
+ ::proc_macro::TokenTree::Group(
+ ::proc_macro::Group::new(
+ ::proc_macro::Delimiter::Parenthesis,
+ quote!($($inner)*),
+ ),
+ ),
+ ),
+ );
+ quote_each_token!($tokens $($rest)*);
+ };
+ ($tokens:ident [ $($inner:tt)* ] $($rest:tt)*) => {
+ <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+ &mut $tokens,
+ ::std::iter::once(
+ ::proc_macro::TokenTree::Group(
+ ::proc_macro::Group::new(
+ ::proc_macro::Delimiter::Bracket,
+ quote!($($inner)*),
+ ),
+ ),
+ ),
+ );
+ quote_each_token!($tokens $($rest)*);
+ };
+ ($tokens:ident { $($inner:tt)* } $($rest:tt)*) => {
+ <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+ &mut $tokens,
+ ::std::iter::once(
+ ::proc_macro::TokenTree::Group(
+ ::proc_macro::Group::new(
+ ::proc_macro::Delimiter::Brace,
+ quote!($($inner)*),
+ ),
+ ),
+ ),
+ );
+ quote_each_token!($tokens $($rest)*);
+ };
+ ($tokens:ident $punct:tt $($rest:tt)*) => {
+ <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+ &mut $tokens,
+ stringify!($punct).parse::<::proc_macro::TokenStream>(),
+ );
+ quote_each_token!($tokens $($rest)*);
+ };
+ ($tokens:ident) => {};
+}
+
+pub trait Tokens {
+ fn extend(tokens: &mut TokenStream, var: &Self);
+}
+
+impl Tokens for Ident {
+ fn extend(tokens: &mut TokenStream, var: &Self) {
+ tokens.extend(iter::once(TokenTree::Ident(var.clone())));
+ }
+}
+
+impl Tokens for TokenStream {
+ fn extend(tokens: &mut TokenStream, var: &Self) {
+ tokens.extend(var.clone());
+ }
+}
+
+impl<T: Tokens> Tokens for Option<T> {
+ fn extend(tokens: &mut TokenStream, var: &Self) {
+ if let Some(var) = var {
+ T::extend(tokens, var);
+ }
+ }
+}
+
+impl<T: Tokens> Tokens for &T {
+ fn extend(tokens: &mut TokenStream, var: &Self) {
+ T::extend(tokens, var);
+ }
+}
--- /dev/null
+#[rustversion::attr(not(nightly), ignore)]
+#[test]
+fn ui() {
+ let t = trybuild::TestCases::new();
+ t.compile_fail("tests/ui/*.rs");
+}
--- /dev/null
+use proc_macro_hack::proc_macro_hack;
+
+#[proc_macro_hack]
+fn my_macro(input: TokenStream) -> TokenStream {
+ unimplemented!()
+}
+
+fn main() {}
--- /dev/null
+error: functions tagged with `#[proc_macro_hack]` must be `pub`
+ --> $DIR/private.rs:4:1
+ |
+4 | fn my_macro(input: TokenStream) -> TokenStream {
+ | ^^
--- /dev/null
+use proc_macro_hack::proc_macro_hack;
+
+#[proc_macro_hack(fake_call_site)]
+pub fn my_macro(input: TokenStream) -> TokenStream {
+ unimplemented!()
+}
+
+fn main() {}
--- /dev/null
+error: unexpected argument to proc_macro_hack macro implementation; args are only accepted on the macro declaration (the `pub use`)
+ --> $DIR/unexpected-arg.rs:3:19
+ |
+3 | #[proc_macro_hack(fake_call_site)]
+ | ^^^^^^^^^^^^^^
--- /dev/null
+use proc_macro_hack::proc_macro_hack;
+
+#[proc_macro_hack]
+pub struct What;
+
+fn main() {}
--- /dev/null
+error: unexpected input to #[proc_macro_hack]
+ --> $DIR/unexpected.rs:4:5
+ |
+4 | pub struct What;
+ | ^^^^^^
--- /dev/null
+use proc_macro_hack::proc_macro_hack;
+
+#[proc_macro_hack(fake_call_site, support_nexted)]
+pub use demo::some_macro;
+
+fn main() {}
--- /dev/null
+error: expected one of: `support_nested`, `internal_macro_calls`, `fake_call_site`, `only_hack_old_rustc`
+ --> $DIR/unknown-arg.rs:3:35
+ |
+3 | #[proc_macro_hack(fake_call_site, support_nexted)]
+ | ^^^^^^^^^^^^^^
projects / platform / upstream / rust-proc-macro-hack.git / commitdiff