refactor loan to not return result<>
This commit is contained in:
Niko Matsakis
parent
01a2e99639
commit
00849191ce
@ -72,10 +72,11 @@ type root_map_key = {id: ast::node_id, derefs: uint};
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type mutbl_map = std::map::hashmap<ast::node_id, ()>;
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enum bckerr_code {
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err_mutbl(ast::mutability, ast::mutability),
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err_mut_uniq,
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err_mut_variant,
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err_preserve_gc
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err_preserve_gc,
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err_mutbl(ast::mutability,
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ast::mutability)
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}
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type bckerr = {cmt: cmt, code: bckerr_code};
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@ -136,32 +137,6 @@ enum loan_path {
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// a complete record of a loan that was granted
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type loan = {lp: @loan_path, cmt: cmt, mutbl: ast::mutability};
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fn sup_mutbl(req_m: ast::mutability,
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act_m: ast::mutability) -> bool {
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alt (req_m, act_m) {
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(m_const, _) |
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(m_imm, m_imm) |
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(m_mutbl, m_mutbl) {
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true
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}
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(_, m_const) |
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(m_imm, m_mutbl) |
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(m_mutbl, m_imm) {
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false
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}
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}
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}
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fn check_sup_mutbl(req_m: ast::mutability,
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cmt: cmt) -> bckres<()> {
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if sup_mutbl(req_m, cmt.mutbl) {
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ok(())
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} else {
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err({cmt:cmt, code:err_mutbl(req_m, cmt.mutbl)})
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}
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}
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fn save_and_restore<T:copy,U>(&t: T, f: fn() -> U) -> U {
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let old_t = t;
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let u <- f();
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@ -278,12 +253,12 @@ impl methods for gather_loan_ctxt {
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// also entail "rooting" GC'd pointers, which means ensuring
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// dynamically that they are not freed.
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fn guarantee_valid(cmt: cmt,
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mutbl: ast::mutability,
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req_mutbl: ast::mutability,
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scope_r: ty::region) {
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#debug["guarantee_valid(cmt=%s, mutbl=%s, scope_r=%s)",
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#debug["guarantee_valid(cmt=%s, req_mutbl=%s, scope_r=%s)",
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self.bccx.cmt_to_repr(cmt),
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self.bccx.mut_to_str(mutbl),
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self.bccx.mut_to_str(req_mutbl),
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region_to_str(self.tcx(), scope_r)];
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let _i = indenter();
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@ -300,10 +275,8 @@ impl methods for gather_loan_ctxt {
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some(_) {
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alt scope_r {
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ty::re_scope(scope_id) {
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alt self.bccx.loan(cmt, mutbl) {
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ok(loans) { self.add_loans(scope_id, loans); }
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err(e) { self.bccx.report(e); }
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}
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let loans = self.bccx.loan(cmt, req_mutbl);
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self.add_loans(scope_id, loans);
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}
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_ {
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self.bccx.span_err(
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@ -321,7 +294,7 @@ impl methods for gather_loan_ctxt {
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// rooted in some immutable path)
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none {
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self.bccx.report_if_err(
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check_sup_mutbl(mutbl, cmt).chain { |_ok|
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self.check_mutbl(req_mutbl, cmt).chain { |_ok|
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let opt_scope_id = alt scope_r {
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ty::re_scope(scope_id) { some(scope_id) }
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_ { none }
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@ -333,6 +306,32 @@ impl methods for gather_loan_ctxt {
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}
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}
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// Check that the pat `cmt` is compatible with the required
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// mutability, presuming that it can be preserved to stay alive
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// long enough.
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//
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// For example, if you have an expression like `&x.f` where `x`
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// has type `@mut{f:int}`, this check might fail because `&x.f`
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// reqires an immutable pointer, but `f` lives in (aliased)
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// mutable memory.
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fn check_mutbl(req_mutbl: ast::mutability,
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cmt: cmt) -> bckres<()> {
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alt (req_mutbl, cmt.mutbl) {
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(m_const, _) |
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(m_imm, m_imm) |
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(m_mutbl, m_mutbl) {
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ok(())
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}
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(_, m_const) |
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(m_imm, m_mutbl) |
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(m_mutbl, m_imm) {
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err({cmt: cmt,
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code: err_mutbl(req_mutbl, cmt.mutbl)})
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}
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}
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}
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fn add_loans(scope_id: ast::node_id, loans: @const [loan]) {
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alt self.req_maps.req_loan_map.find(scope_id) {
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some(l) {
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@ -1404,7 +1403,7 @@ impl categorize_methods for borrowck_ctxt {
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fn bckerr_code_to_str(code: bckerr_code) -> str {
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alt code {
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err_mutbl(req, act) {
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#fmt["mutability mismatch, required %s but found %s",
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#fmt["creating %s alias to aliasable, %s memory",
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self.mut_to_str(req), self.mut_to_str(act)]
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}
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err_mut_uniq {
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@ -1647,29 +1646,25 @@ type loan_ctxt = @{
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};
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impl loan_methods for borrowck_ctxt {
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fn loan(cmt: cmt,
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mutbl: ast::mutability) -> bckres<@const [loan]> {
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fn loan(cmt: cmt, mutbl: ast::mutability) -> @const [loan] {
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let lc = @{bccx: self, loans: @mut []};
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alt lc.loan(cmt, mutbl) {
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ok(()) { ok(lc.loans) }
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err(e) { err(e) }
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}
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lc.loan(cmt, mutbl);
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ret lc.loans;
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}
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}
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impl loan_methods for loan_ctxt {
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fn ok_with_loan_of(cmt: cmt,
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mutbl: ast::mutability) -> bckres<()> {
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mutbl: ast::mutability) {
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// Note: all cmt's that we deal with will have a non-none lp, because
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// the entry point into this routine, `borrowck_ctxt::loan()`, rejects
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// any cmt with a none-lp.
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*self.loans += [{lp:option::get(cmt.lp),
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cmt:cmt,
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mutbl:mutbl}];
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ok(())
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}
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fn loan(cmt: cmt, req_mutbl: ast::mutability) -> bckres<()> {
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fn loan(cmt: cmt, req_mutbl: ast::mutability) {
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#debug["loan(%s, %s)",
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self.bccx.cmt_to_repr(cmt),
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@ -1711,9 +1706,8 @@ impl loan_methods for loan_ctxt {
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m_const | m_mutbl { m_const }
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};
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self.loan(cmt_base, base_mutbl).chain { |_ok|
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self.ok_with_loan_of(cmt, req_mutbl)
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}
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self.loan(cmt_base, base_mutbl);
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self.ok_with_loan_of(cmt, req_mutbl)
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}
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cat_comp(cmt1, comp_variant) |
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cat_deref(cmt1, _, uniq_ptr) {
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@ -1723,9 +1717,8 @@ impl loan_methods for loan_ctxt {
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//
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// Unique pointers: the base must be immutable, because if
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// it is overwritten, the unique content will be freed.
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self.loan(cmt1, m_imm).chain { |_ok|
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self.ok_with_loan_of(cmt, req_mutbl)
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}
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self.loan(cmt1, m_imm);
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self.ok_with_loan_of(cmt, req_mutbl)
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}
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cat_deref(cmt1, _, unsafe_ptr) |
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cat_deref(cmt1, _, gc_ptr) |
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