bjoernager/rust
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prefer if let to match with None => { } arm in some places

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In #34268 (8531d581), we replaced matches of None to the unit value `()`
with `if let`s in places where it was deemed that this made the code
unambiguously clearer and more idiomatic. In #34638 (d37edef9), we did
the same for matches of None to the empty block `{}`.

A casual observer, upon seeing these commits fly by, might suppose that
the matter was then settled, that no further pull requests on this
utterly trivial point of style could or would be made. Unless ...

It turns out that sometimes people write the empty block with a space in
between the braces. Who knew?
This commit is contained in:
Zack M. Davis 2016-10-17 19:00:20 -07:00
parent e0111758eb
commit 1e7cd5edcc
11 changed files with 97 additions and 136 deletions
Download patch file Download diff file Expand all files Collapse all files

5
src/librustc/infer/freshen.rs
View file

@ -61,9 +61,8 @@ impl<'a, 'gcx, 'tcx> TypeFreshener<'a, 'gcx, 'tcx> {
-> Ty<'tcx> where
F: FnOnce(u32) -> ty::InferTy,
{
match opt_ty {
Some(ty) => { return ty.fold_with(self); }
None => { }
if let Some(ty) = opt_ty {
return ty.fold_with(self);
}
match self.freshen_map.entry(key) {

37
src/librustc/middle/region.rs
View file

@ -478,12 +478,9 @@ impl RegionMaps {
//! Returns the scope when temp created by expr_id will be cleaned up
// check for a designated rvalue scope
match self.rvalue_scopes.borrow().get(&expr_id) {
Some(&s) => {
debug!("temporary_scope({:?}) = {:?} [custom]", expr_id, s);
return Some(s);
}
None => { }
if let Some(&s) = self.rvalue_scopes.borrow().get(&expr_id) {
debug!("temporary_scope({:?}) = {:?} [custom]", expr_id, s);
return Some(s);
}
let scope_map : &[CodeExtent] = &self.scope_map.borrow();
@ -928,19 +925,15 @@ fn resolve_local(visitor: &mut RegionResolutionVisitor, local: &hir::Local) {
//
// FIXME(#6308) -- Note that `[]` patterns work more smoothly post-DST.
match local.init {
Some(ref expr) => {
record_rvalue_scope_if_borrow_expr(visitor, &expr, blk_scope);
if let Some(ref expr) = local.init {
record_rvalue_scope_if_borrow_expr(visitor, &expr, blk_scope);
let is_borrow =
if let Some(ref ty) = local.ty { is_borrowed_ty(&ty) } else { false };
let is_borrow =
if let Some(ref ty) = local.ty { is_borrowed_ty(&ty) } else { false };
if is_binding_pat(&local.pat) || is_borrow {
record_rvalue_scope(visitor, &expr, blk_scope);
}
if is_binding_pat(&local.pat) || is_borrow {
record_rvalue_scope(visitor, &expr, blk_scope);
}
None => { }
}
intravisit::walk_local(visitor, local);
@ -1023,16 +1016,12 @@ fn resolve_local(visitor: &mut RegionResolutionVisitor, local: &hir::Local) {
record_rvalue_scope_if_borrow_expr(visitor, &subexpr, blk_id)
}
hir::ExprBlock(ref block) => {
match block.expr {
Some(ref subexpr) => {
record_rvalue_scope_if_borrow_expr(
visitor, &subexpr, blk_id);
}
None => { }
if let Some(ref subexpr) = block.expr {
record_rvalue_scope_if_borrow_expr(
visitor, &subexpr, blk_id);
}
}
_ => {
}
_ => {}
}
}

5
src/librustc/traits/project.rs
View file

@ -1405,9 +1405,8 @@ impl<'tcx> ProjectionCache<'tcx> {
/// cache hit, so it's actually a good thing).
fn try_start(&mut self, key: ty::ProjectionTy<'tcx>)
-> Result<(), ProjectionCacheEntry<'tcx>> {
match self.map.get(&key) {
Some(entry) => return Err(entry.clone()),
None => { }
if let Some(entry) = self.map.get(&key) {
return Err(entry.clone());
}
self.map.insert(key, ProjectionCacheEntry::InProgress);

13
src/librustc/traits/select.rs
View file

@ -788,14 +788,11 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
stack);
assert!(!stack.obligation.predicate.has_escaping_regions());
match self.check_candidate_cache(&cache_fresh_trait_pred) {
Some(c) => {
debug!("CACHE HIT: SELECT({:?})={:?}",
cache_fresh_trait_pred,
c);
return c;
}
None => { }
if let Some(c) = self.check_candidate_cache(&cache_fresh_trait_pred) {
debug!("CACHE HIT: SELECT({:?})={:?}",
cache_fresh_trait_pred,
c);
return c;
}
// If no match, compute result and insert into cache.

112
src/librustc_borrowck/borrowck/check_loans.rs
View file

@ -135,15 +135,12 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for CheckLoanCtxt<'a, 'tcx> {
borrow_id, cmt, loan_region,
bk, loan_cause);
match opt_loan_path(&cmt) {
Some(lp) => {
let moved_value_use_kind = match loan_cause {
euv::ClosureCapture(_) => MovedInCapture,
_ => MovedInUse,
};
self.check_if_path_is_moved(borrow_id, borrow_span, moved_value_use_kind, &lp);
}
None => { }
if let Some(lp) = opt_loan_path(&cmt) {
let moved_value_use_kind = match loan_cause {
euv::ClosureCapture(_) => MovedInCapture,
_ => MovedInUse,
};
self.check_if_path_is_moved(borrow_id, borrow_span, moved_value_use_kind, &lp);
}
self.check_for_conflicting_loans(borrow_id);
@ -158,33 +155,29 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for CheckLoanCtxt<'a, 'tcx> {
debug!("mutate(assignment_id={}, assignee_cmt={:?})",
assignment_id, assignee_cmt);
match opt_loan_path(&assignee_cmt) {
Some(lp) => {
match mode {
MutateMode::Init | MutateMode::JustWrite => {
// In a case like `path = 1`, then path does not
// have to be *FULLY* initialized, but we still
// must be careful lest it contains derefs of
// pointers.
self.check_if_assigned_path_is_moved(assignee_cmt.id,
assignment_span,
MovedInUse,
&lp);
}
MutateMode::WriteAndRead => {
// In a case like `path += 1`, then path must be
// fully initialized, since we will read it before
// we write it.
self.check_if_path_is_moved(assignee_cmt.id,
assignment_span,
MovedInUse,
&lp);
}
if let Some(lp) = opt_loan_path(&assignee_cmt) {
match mode {
MutateMode::Init | MutateMode::JustWrite => {
// In a case like `path = 1`, then path does not
// have to be *FULLY* initialized, but we still
// must be careful lest it contains derefs of
// pointers.
self.check_if_assigned_path_is_moved(assignee_cmt.id,
assignment_span,
MovedInUse,
&lp);
}
MutateMode::WriteAndRead => {
// In a case like `path += 1`, then path must be
// fully initialized, since we will read it before
// we write it.
self.check_if_path_is_moved(assignee_cmt.id,
assignment_span,
MovedInUse,
&lp);
}
}
None => { }
}
self.check_assignment(assignment_id, assignment_span, assignee_cmt);
}
@ -601,39 +594,36 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
span: Span,
cmt: mc::cmt<'tcx>,
mode: euv::ConsumeMode) {
match opt_loan_path(&cmt) {
Some(lp) => {
let moved_value_use_kind = match mode {
euv::Copy => {
self.check_for_copy_of_frozen_path(id, span, &lp);
MovedInUse
}
euv::Move(_) => {
match self.move_data.kind_of_move_of_path(id, &lp) {
None => {
// Sometimes moves don't have a move kind;
// this either means that the original move
// was from something illegal to move,
// or was moved from referent of an unsafe
// pointer or something like that.
if let Some(lp) = opt_loan_path(&cmt) {
let moved_value_use_kind = match mode {
euv::Copy => {
self.check_for_copy_of_frozen_path(id, span, &lp);
MovedInUse
}
euv::Move(_) => {
match self.move_data.kind_of_move_of_path(id, &lp) {
None => {
// Sometimes moves don't have a move kind;
// this either means that the original move
// was from something illegal to move,
// or was moved from referent of an unsafe
// pointer or something like that.
MovedInUse
}
Some(move_kind) => {
self.check_for_move_of_borrowed_path(id, span,
&lp, move_kind);
if move_kind == move_data::Captured {
MovedInCapture
} else {
MovedInUse
}
Some(move_kind) => {
self.check_for_move_of_borrowed_path(id, span,
&lp, move_kind);
if move_kind == move_data::Captured {
MovedInCapture
} else {
MovedInUse
}
}
}
}
};
}
};
self.check_if_path_is_moved(id, span, moved_value_use_kind, &lp);
}
None => { }
self.check_if_path_is_moved(id, span, moved_value_use_kind, &lp);
}
}

5
src/librustc_trans/callee.rs
View file

@ -302,9 +302,8 @@ fn trans_fn_pointer_shim<'a, 'tcx>(
};
// Check if we already trans'd this shim.
match ccx.fn_pointer_shims().borrow().get(&bare_fn_ty_maybe_ref) {
Some(&llval) => { return llval; }
None => { }
if let Some(&llval) = ccx.fn_pointer_shims().borrow().get(&bare_fn_ty_maybe_ref) {
return llval;
}
debug!("trans_fn_pointer_shim(bare_fn_ty={:?})",

5
src/librustc_trans/meth.rs
View file

@ -119,9 +119,8 @@ pub fn get_vtable<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
debug!("get_vtable(trait_ref={:?})", trait_ref);
// Check the cache.
match ccx.vtables().borrow().get(&trait_ref) {
Some(&val) => { return val }
None => { }
if let Some(&val) = ccx.vtables().borrow().get(&trait_ref) {
return val;
}
// Not in the cache. Build it.

5
src/librustc_typeck/astconv.rs
View file

@ -1629,9 +1629,8 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
let tcx = self.tcx();
let cache = self.ast_ty_to_ty_cache();
match cache.borrow().get(&ast_ty.id) {
Some(ty) => { return ty; }
None => { }
if let Some(ty) = cache.borrow().get(&ast_ty.id) {
return ty;
}
let result_ty = match ast_ty.node {

24
src/librustc_typeck/check/mod.rs
View file

@ -742,17 +742,14 @@ pub fn check_item_type<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>, it: &'tcx hir::Item) {
hir::ItemImpl(.., ref impl_items) => {
debug!("ItemImpl {} with id {}", it.name, it.id);
let impl_def_id = ccx.tcx.map.local_def_id(it.id);
match ccx.tcx.impl_trait_ref(impl_def_id) {
Some(impl_trait_ref) => {
check_impl_items_against_trait(ccx,
it.span,
impl_def_id,
&impl_trait_ref,
impl_items);
let trait_def_id = impl_trait_ref.def_id;
check_on_unimplemented(ccx, trait_def_id, it);
}
None => { }
if let Some(impl_trait_ref) = ccx.tcx.impl_trait_ref(impl_def_id) {
check_impl_items_against_trait(ccx,
it.span,
impl_def_id,
&impl_trait_ref,
impl_items);
let trait_def_id = impl_trait_ref.def_id;
check_on_unimplemented(ccx, trait_def_id, it);
}
}
hir::ItemTrait(..) => {
@ -1812,9 +1809,8 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
f: F) where
F: FnOnce(&ty::ItemSubsts<'tcx>),
{
match self.tables.borrow().item_substs.get(&id) {
Some(s) => { f(s) }
None => { }
if let Some(s) = self.tables.borrow().item_substs.get(&id) {
f(s);
}
}

11
src/librustc_typeck/collect.rs
View file

@ -156,13 +156,10 @@ impl<'a,'tcx> CrateCtxt<'a,'tcx> {
{
{
let mut stack = self.stack.borrow_mut();
match stack.iter().enumerate().rev().find(|&(_, r)| *r == request) {
None => { }
Some((i, _)) => {
let cycle = &stack[i..];
self.report_cycle(span, cycle);
return Err(ErrorReported);
}
if let Some((i, _)) = stack.iter().enumerate().rev().find(|&(_, r)| *r == request) {
let cycle = &stack[i..];
self.report_cycle(span, cycle);
return Err(ErrorReported);
}
stack.push(request);
}

11
src/libsyntax/print/pprust.rs
View file

@ -2450,13 +2450,10 @@ impl<'a> State<'a> {
|s, ty| s.print_type(&ty)));
try!(word(&mut self.s, ")"));
match data.output {
None => { }
Some(ref ty) => {
try!(self.space_if_not_bol());
try!(self.word_space("->"));
try!(self.print_type(&ty));
}
if let Some(ref ty) = data.output {
try!(self.space_if_not_bol());
try!(self.word_space("->"));
try!(self.print_type(&ty));
}
}
}