diff options
| -rw-r--r-- | src/librustc/middle/const_eval.rs | 40 |
1 files changed, 34 insertions, 6 deletions
diff --git a/src/librustc/middle/const_eval.rs b/src/librustc/middle/const_eval.rs index 0c9f9d2a530..23844739a6b 100644 --- a/src/librustc/middle/const_eval.rs +++ b/src/librustc/middle/const_eval.rs @@ -25,6 +25,7 @@ use syntax::parse::token::InternedString; use syntax::ptr::P; use syntax::{ast_map, ast_util, codemap}; +use std::num::wrapping::OverflowingOps; use std::cmp::Ordering; use std::collections::hash_map::Entry::Vacant; use std::{i8, i16, i32, i64}; @@ -206,6 +207,33 @@ pub fn eval_const_expr(tcx: &ty::ctxt, e: &Expr) -> const_val { } } +fn checked_add_int(a: i64, b: i64) -> Result<const_val, String> { + let (ret, oflo) = a.overflowing_add(b); + if !oflo { Ok(const_int(ret)) } else { Err(format!("constant arithmetic overflow")) } +} +fn checked_sub_int(a: i64, b: i64) -> Result<const_val, String> { + let (ret, oflo) = a.overflowing_sub(b); + if !oflo { Ok(const_int(ret)) } else { Err(format!("constant arithmetic overflow")) } +} +fn checked_mul_int(a: i64, b: i64) -> Result<const_val, String> { + let (ret, oflo) = a.overflowing_mul(b); + if !oflo { Ok(const_int(ret)) } else { Err(format!("constant arithmetic overflow")) } +} + +fn checked_add_uint(a: u64, b: u64) -> Result<const_val, String> { + let (ret, oflo) = a.overflowing_add(b); + if !oflo { Ok(const_uint(ret)) } else { Err(format!("constant arithmetic overflow")) } +} +fn checked_sub_uint(a: u64, b: u64) -> Result<const_val, String> { + let (ret, oflo) = a.overflowing_sub(b); + if !oflo { Ok(const_uint(ret)) } else { Err(format!("constant arithmetic overflow")) } +} +fn checked_mul_uint(a: u64, b: u64) -> Result<const_val, String> { + let (ret, oflo) = a.overflowing_mul(b); + if !oflo { Ok(const_uint(ret)) } else { Err(format!("constant arithmetic overflow")) } +} + + pub fn eval_const_expr_partial<'tcx>(tcx: &ty::ctxt<'tcx>, e: &Expr, ty_hint: Option<Ty<'tcx>>) @@ -276,9 +304,9 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &ty::ctxt<'tcx>, } }; match op.node { - ast::BiAdd => Ok(const_int(a + b)), - ast::BiSub => Ok(const_int(a - b)), - ast::BiMul => Ok(const_int(a * b)), + ast::BiAdd => checked_add_int(a, b), + ast::BiSub => checked_sub_int(a, b), + ast::BiMul => checked_mul_int(a, b), ast::BiDiv => { if b == 0 { Err("attempted to divide by zero".to_string()) @@ -312,9 +340,9 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &ty::ctxt<'tcx>, } (Ok(const_uint(a)), Ok(const_uint(b))) => { match op.node { - ast::BiAdd => Ok(const_uint(a + b)), - ast::BiSub => Ok(const_uint(a - b)), - ast::BiMul => Ok(const_uint(a * b)), + ast::BiAdd => checked_add_uint(a, b), + ast::BiSub => checked_sub_uint(a, b), + ast::BiMul => checked_mul_uint(a, b), ast::BiDiv if b == 0 => { Err("attempted to divide by zero".to_string()) } |