diff --git a/src/libcore/macros.rs b/src/libcore/macros.rs index 52eb9f29d57..8a87bea71e2 100644 --- a/src/libcore/macros.rs +++ b/src/libcore/macros.rs @@ -76,6 +76,7 @@ macro_rules! panic { /// ``` #[macro_export] #[stable(feature = "rust1", since = "1.0.0")] +#[cfg(stage0)] macro_rules! assert { ($cond:expr) => ( if !$cond { @@ -784,4 +785,18 @@ mod builtin { ($file:expr) => ({ /* compiler built-in */ }); ($file:expr,) => ({ /* compiler built-in */ }); } + + /// Ensure that a boolean expression is `true` at runtime. + /// + /// For more information, see the documentation for [`std::assert!`]. + /// + /// [`std::assert!`]: ../std/macro.assert.html + #[macro_export] + #[stable(feature = "rust1", since = "1.0.0")] + #[cfg(dox)] + macro_rules! assert { + ($cond:expr) => ({ /* compiler built-in */ }); + ($cond:expr,) => ({ /* compiler built-in */ }); + ($cond:expr, $($arg:tt)+) => ({ /* compiler built-in */ }); + } } diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs index a7e1c0ce732..b2e45f0f437 100644 --- a/src/libstd/lib.rs +++ b/src/libstd/lib.rs @@ -355,8 +355,9 @@ use prelude::v1::*; // We want to re-export a few macros from core but libcore has already been // imported by the compiler (via our #[no_std] attribute) In this case we just // add a new crate name so we can attach the re-exports to it. -#[macro_reexport(assert, assert_eq, assert_ne, debug_assert, debug_assert_eq, +#[macro_reexport(assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne, unreachable, unimplemented, write, writeln, try)] +#[cfg_attr(stage0, macro_reexport(assert))] extern crate core as __core; #[macro_use] diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs index a18c811d196..da982af498b 100644 --- a/src/libstd/macros.rs +++ b/src/libstd/macros.rs @@ -719,6 +719,60 @@ pub mod builtin { ($file:expr) => ({ /* compiler built-in */ }); ($file:expr,) => ({ /* compiler built-in */ }); } + + /// Ensure that a boolean expression is `true` at runtime. + /// + /// This will invoke the [`panic!`] macro if the provided expression cannot be + /// evaluated to `true` at runtime. + /// + /// # Uses + /// + /// Assertions are always checked in both debug and release builds, and cannot + /// be disabled. See [`debug_assert!`] for assertions that are not enabled in + /// release builds by default. + /// + /// Unsafe code relies on `assert!` to enforce run-time invariants that, if + /// violated could lead to unsafety. + /// + /// Other use-cases of `assert!` include [testing] and enforcing run-time + /// invariants in safe code (whose violation cannot result in unsafety). + /// + /// # Custom Messages + /// + /// This macro has a second form, where a custom panic message can + /// be provided with or without arguments for formatting. See [`std::fmt`] + /// for syntax for this form. + /// + /// [`panic!`]: macro.panic.html + /// [`debug_assert!`]: macro.debug_assert.html + /// [testing]: ../book/second-edition/ch11-01-writing-tests.html#checking-results-with-the-assert-macro + /// [`std::fmt`]: ../std/fmt/index.html + /// + /// # Examples + /// + /// ``` + /// // the panic message for these assertions is the stringified value of the + /// // expression given. + /// assert!(true); + /// + /// fn some_computation() -> bool { true } // a very simple function + /// + /// assert!(some_computation()); + /// + /// // assert with a custom message + /// let x = true; + /// assert!(x, "x wasn't true!"); + /// + /// let a = 3; let b = 27; + /// assert!(a + b == 30, "a = {}, b = {}", a, b); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[macro_export] + macro_rules! assert { + ($cond:expr) => ({ /* compiler built-in */ }); + ($cond:expr,) => ({ /* compiler built-in */ }); + ($cond:expr, $($arg:tt)+) => ({ /* compiler built-in */ }); + } } /// A macro for defining #[cfg] if-else statements. diff --git a/src/libsyntax_ext/assert.rs b/src/libsyntax_ext/assert.rs new file mode 100644 index 00000000000..7962ec26c37 --- /dev/null +++ b/src/libsyntax_ext/assert.rs @@ -0,0 +1,64 @@ +// Copyright 2018 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use syntax::ast::*; +use syntax::codemap::Spanned; +use syntax::ext::base::*; +use syntax::ext::build::AstBuilder; +use syntax::parse::token; +use syntax::print::pprust; +use syntax::tokenstream::{TokenStream, TokenTree}; +use syntax_pos::Span; + +pub fn expand_assert<'cx>( + cx: &'cx mut ExtCtxt, + sp: Span, + tts: &[TokenTree], +) -> Box { + let mut parser = cx.new_parser_from_tts(tts); + let cond_expr = panictry!(parser.parse_expr()); + let custom_msg_args = if parser.eat(&token::Comma) { + let ts = parser.parse_tokens(); + if !ts.is_empty() { + Some(ts) + } else { + None + } + } else { + None + }; + + let sp = sp.with_ctxt(sp.ctxt().apply_mark(cx.current_expansion.mark)); + let panic_call = Mac_ { + path: Path::from_ident(sp, Ident::from_str("panic")), + tts: if let Some(ts) = custom_msg_args { + ts.into() + } else { + let panic_str = format!("assertion failed: {}", pprust::expr_to_string(&cond_expr)); + TokenStream::from(token::Literal( + token::Lit::Str_(Name::intern(&panic_str)), + None, + )).into() + }, + }; + let if_expr = cx.expr_if( + sp, + cx.expr(sp, ExprKind::Unary(UnOp::Not, cond_expr)), + cx.expr( + sp, + ExprKind::Mac(Spanned { + span: sp, + node: panic_call, + }), + ), + None, + ); + MacEager::expr(if_expr) +} diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs index 772dec72ab9..a01878530b2 100644 --- a/src/libsyntax_ext/lib.rs +++ b/src/libsyntax_ext/lib.rs @@ -26,6 +26,7 @@ extern crate proc_macro; extern crate rustc_data_structures; extern crate rustc_errors as errors; +mod assert; mod asm; mod cfg; mod compile_error; @@ -111,6 +112,7 @@ pub fn register_builtins(resolver: &mut syntax::ext::base::Resolver, log_syntax: log_syntax::expand_syntax_ext, trace_macros: trace_macros::expand_trace_macros, compile_error: compile_error::expand_compile_error, + assert: assert::expand_assert, } // format_args uses `unstable` things internally.