From fbde11297fc06efa8e1e63527467ef7e65d072fa Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Adolfo=20Ochagav=C3=ADa?= Date: Mon, 24 Nov 2014 12:46:02 +0100 Subject: [PATCH 1/2] Allow constant struct fields and tuple indexing --- src/librustc/middle/const_eval.rs | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/src/librustc/middle/const_eval.rs b/src/librustc/middle/const_eval.rs index 98ac7e413ca7c..7afbf92235147 100644 --- a/src/librustc/middle/const_eval.rs +++ b/src/librustc/middle/const_eval.rs @@ -567,6 +567,34 @@ pub fn eval_const_expr_partial(tcx: &ty::ctxt, e: &Expr) -> Result Ok(const_int(0i64)) } } + ast::ExprTupField(ref base, index) => { + // Get the base tuple if it is constant + if let Some(&ast::ExprTup(ref fields)) = lookup_const(tcx, &**base).map(|s| &s.node) { + // Check that the given index is within bounds and evaluate its value + if fields.len() > index.node { + return eval_const_expr_partial(tcx, &*fields[index.node]) + } else { + return Err("tuple index out of bounds".to_string()) + } + } + + Err("non-constant struct in constant expr".to_string()) + } + ast::ExprField(ref base, field_name) => { + // Get the base expression if it is a struct and it is constant + if let Some(&ast::ExprStruct(_, ref fields, _)) = lookup_const(tcx, &**base) + .map(|s| &s.node) { + // Check that the given field exists and evaluate it + if let Some(f) = fields.iter().find(|f| + f.ident.node.as_str() == field_name.node.as_str()) { + return eval_const_expr_partial(tcx, &*f.expr) + } else { + return Err("nonexistent struct field".to_string()) + } + } + + Err("non-constant struct in constant expr".to_string()) + } _ => Err("unsupported constant expr".to_string()) } } From 080e625dae129aad7db4e69d74fa0f767f700325 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Adolfo=20Ochagav=C3=ADa?= Date: Tue, 25 Nov 2014 10:19:58 +0100 Subject: [PATCH 2/2] Add tests for issue 19244 --- src/test/compile-fail/issue-19244-1.rs | 18 ++++++++++++++++++ src/test/compile-fail/issue-19244-2.rs | 17 +++++++++++++++++ src/test/run-pass/issue-19244.rs | 23 +++++++++++++++++++++++ 3 files changed, 58 insertions(+) create mode 100644 src/test/compile-fail/issue-19244-1.rs create mode 100644 src/test/compile-fail/issue-19244-2.rs create mode 100644 src/test/run-pass/issue-19244.rs diff --git a/src/test/compile-fail/issue-19244-1.rs b/src/test/compile-fail/issue-19244-1.rs new file mode 100644 index 0000000000000..4fcbb87889054 --- /dev/null +++ b/src/test/compile-fail/issue-19244-1.rs @@ -0,0 +1,18 @@ +// Copyright 2012 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. + +#![feature(tuple_indexing)] + +const TUP: (uint,) = (42,); + +fn main() { + let a: [int, ..TUP.1]; + //~^ ERROR expected constant expr for array length: tuple index out of bounds +} diff --git a/src/test/compile-fail/issue-19244-2.rs b/src/test/compile-fail/issue-19244-2.rs new file mode 100644 index 0000000000000..d9aeecc02222c --- /dev/null +++ b/src/test/compile-fail/issue-19244-2.rs @@ -0,0 +1,17 @@ +// Copyright 2012 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. + +struct MyStruct { field: uint } +const STRUCT: MyStruct = MyStruct { field: 42 }; + +fn main() { + let a: [int, ..STRUCT.nonexistent_field]; + //~^ ERROR expected constant expr for array length: nonexistent struct field +} diff --git a/src/test/run-pass/issue-19244.rs b/src/test/run-pass/issue-19244.rs new file mode 100644 index 0000000000000..fecddea13e0f8 --- /dev/null +++ b/src/test/run-pass/issue-19244.rs @@ -0,0 +1,23 @@ +// Copyright 2014 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. + +#![feature(tuple_indexing)] + +struct MyStruct { field: uint } +const STRUCT: MyStruct = MyStruct { field: 42 }; +const TUP: (uint,) = (43,); + +fn main() { + let a = [0i, ..STRUCT.field]; + let b = [0i, ..TUP.0]; + + assert!(a.len() == 42); + assert!(b.len() == 43); +}