diff options
Diffstat (limited to 'src/rustc/middle/borrowck.rs')
| -rw-r--r-- | src/rustc/middle/borrowck.rs | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/src/rustc/middle/borrowck.rs b/src/rustc/middle/borrowck.rs index 85ee5b1c957..8cf6671a3d4 100644 --- a/src/rustc/middle/borrowck.rs +++ b/src/rustc/middle/borrowck.rs @@ -541,6 +541,15 @@ enum assignment_type { } impl methods for assignment_type { + fn checked_by_liveness() -> bool { + // the liveness pass guarantees that immutable local variables + // are only assigned once; but it doesn't consider &mut + alt self { + at_straight_up {true} + at_swap {true} + at_mutbl_ref {false} + } + } fn ing_form(desc: str) -> str { alt self { at_straight_up { "assigning to " + desc } @@ -717,6 +726,13 @@ impl methods for check_loan_ctxt { } } + fn is_local_variable(cmt: cmt) -> bool { + alt cmt.cat { + cat_local(_) {true} + _ {false} + } + } + fn is_self_field(cmt: cmt) -> bool { alt cmt.cat { cat_comp(cmt_base, comp_field(_)) { @@ -735,9 +751,13 @@ impl methods for check_loan_ctxt { #debug["check_assignment(cmt=%s)", self.bccx.cmt_to_repr(cmt)]; - // check that the lvalue `ex` is assignable, but be careful - // because assigning to self.foo in a ctor is always allowed. - if !self.in_ctor || !self.is_self_field(cmt) { + if self.in_ctor && self.is_self_field(cmt) + && at.checked_by_liveness() { + // assigning to self.foo in a ctor is always allowed. + } else if self.is_local_variable(cmt) && at.checked_by_liveness() { + // liveness guarantees that immutable local variables + // are only assigned once + } else { alt cmt.mutbl { m_mutbl { /*ok*/ } m_const | m_imm { |