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Replace convenient function remove_prefix() with replace_prefix() 
1 parent 089d4bb commit 9a212c1

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3 files changed

+60
-51
lines changed

3 files changed

+60
-51
lines changed

‎src/librustc_typeck/check/demand.rs

+60-49
Original file line numberDiff line numberDiff line change
@@ -353,6 +353,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
353353
false
354354
}
355355

356+
fn replace_prefix<A, B, C>(&self, s: A, old: B, new: C) -> Option<String>
357+
where
358+
A: AsRef<str>,
359+
B: AsRef<str>,
360+
C: AsRef<str>,
361+
{
362+
let s = s.as_ref();
363+
let old = old.as_ref();
364+
if s.starts_with(old) { Some(new.as_ref().to_owned() + &s[old.len()..]) } else { None }
365+
}
366+
356367
/// This function is used to determine potential "simple" improvements or users' errors and
357368
/// provide them useful help. For example:
358369
///
@@ -393,20 +404,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
393404
// `ExprKind::DropTemps` is semantically irrelevant for these suggestions.
394405
let expr = expr.peel_drop_temps();
395406

396-
let remove_prefix = |s: String, prefix: &str| {
397-
if s.starts_with(prefix) { Some(s[prefix.len()..].to_string()) } else { None }
398-
};
399-
400407
match (&expr.kind, &expected.kind, &checked_ty.kind) {
401408
(_, &ty::Ref(_, exp, _), &ty::Ref(_, check, _)) => match (&exp.kind, &check.kind) {
402409
(&ty::Str, &ty::Array(arr, _) | &ty::Slice(arr)) if arr == self.tcx.types.u8 => {
403410
if let hir::ExprKind::Lit(_) = expr.kind {
404411
if let Ok(src) = sm.span_to_snippet(sp) {
405-
if let Some(src) = remove_prefix(src, "b\"") {
412+
if let Some(src) = self.replace_prefix(src, "b\"", "\"") {
406413
return Some((
407414
sp,
408415
"consider removing the leading `b`",
409-
format!("\"{}", src),
416+
src,
410417
Applicability::MachineApplicable,
411418
));
412419
}
@@ -416,11 +423,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
416423
(&ty::Array(arr, _) | &ty::Slice(arr), &ty::Str) if arr == self.tcx.types.u8 => {
417424
if let hir::ExprKind::Lit(_) = expr.kind {
418425
if let Ok(src) = sm.span_to_snippet(sp) {
419-
if let Some(src) = remove_prefix(src, "\"") {
426+
if let Some(src) = self.replace_prefix(src, "\"", "b\"") {
420427
return Some((
421428
sp,
422429
"consider adding a leading `b`",
423-
format!("b\"{}", src),
430+
src,
424431
Applicability::MachineApplicable,
425432
));
426433
}
@@ -539,7 +546,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
539546
// we may want to suggest removing a `&`.
540547
if sm.is_imported(expr.span) {
541548
if let Ok(src) = sm.span_to_snippet(sp) {
542-
if let Some(src) = remove_prefix(src, "&") {
549+
if let Some(src) = self.replace_prefix(src, "&", "") {
543550
return Some((
544551
sp,
545552
"consider removing the borrow",
@@ -569,52 +576,56 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
569576
if steps > 0 {
570577
// The pointer type implements `Copy` trait so the suggestion is always valid.
571578
if let Ok(src) = sm.span_to_snippet(sp) {
572-
let derefs = "*".repeat(steps);
573-
match mutbl_b {
574-
hir::Mutability::Mut => match mutbl_a {
575-
hir::Mutability::Mut => {
576-
if let Some(src) = remove_prefix(src, "&mut ") {
577-
return Some((
578-
sp,
579-
"consider dereferencing",
580-
format!("&mut {}{}", derefs, src),
581-
Applicability::MachineApplicable,
582-
));
579+
let derefs = &"*".repeat(steps);
580+
if let Some((src, applicability)) = match mutbl_b {
581+
hir::Mutability::Mut => {
582+
let new_prefix = "&mut ".to_owned() + derefs;
583+
match mutbl_a {
584+
hir::Mutability::Mut => {
585+
if let Some(s) =
586+
self.replace_prefix(src, "&mut ", new_prefix)
587+
{
588+
Some((s, Applicability::MachineApplicable))
589+
} else {
590+
None
591+
}
583592
}
584-
}
585-
hir::Mutability::Not => {
586-
if let Some(src) = remove_prefix(src, "&") {
587-
return Some((
588-
sp,
589-
"consider dereferencing",
590-
format!("&mut {}{}", derefs, src),
591-
Applicability::Unspecified,
592-
));
593+
hir::Mutability::Not => {
594+
if let Some(s) =
595+
self.replace_prefix(src, "&", new_prefix)
596+
{
597+
Some((s, Applicability::Unspecified))
598+
} else {
599+
None
600+
}
593601
}
594602
}
595-
},
596-
hir::Mutability::Not => match mutbl_a {
597-
hir::Mutability::Mut => {
598-
if let Some(src) = remove_prefix(src, "&mut ") {
599-
return Some((
600-
sp,
601-
"consider dereferencing",
602-
format!("&{}{}", derefs, src),
603-
Applicability::MachineApplicable,
604-
));
603+
}
604+
hir::Mutability::Not => {
605+
let new_prefix = "&".to_owned() + derefs;
606+
match mutbl_a {
607+
hir::Mutability::Mut => {
608+
if let Some(s) =
609+
self.replace_prefix(src, "&mut ", new_prefix)
610+
{
611+
Some((s, Applicability::MachineApplicable))
612+
} else {
613+
None
614+
}
605615
}
606-
}
607-
hir::Mutability::Not => {
608-
if let Some(src) = remove_prefix(src, "&") {
609-
return Some((
610-
sp,
611-
"consider dereferencing",
612-
format!("&{}{}", derefs, src),
613-
Applicability::MachineApplicable,
614-
));
616+
hir::Mutability::Not => {
617+
if let Some(s) =
618+
self.replace_prefix(src, "&", new_prefix)
619+
{
620+
Some((s, Applicability::MachineApplicable))
621+
} else {
622+
None
623+
}
615624
}
616625
}
617-
},
626+
}
627+
} {
628+
return Some((sp, "consider dereferencing", src, applicability));
618629
}
619630
}
620631
}

‎src/test/ui/issues/issue-71676-1.fixed

-1
Original file line numberDiff line numberDiff line change
@@ -50,5 +50,4 @@ fn main() {
5050

5151
let mut a = Emm(Foo(Bar(0)));
5252
let _: *mut u8 = &mut ***a; //~ ERROR mismatched types
53-
5453
}

‎src/test/ui/issues/issue-71676-1.rs

-1
Original file line numberDiff line numberDiff line change
@@ -50,5 +50,4 @@ fn main() {
5050

5151
let mut a = Emm(Foo(Bar(0)));
5252
let _: *mut u8 = &mut a; //~ ERROR mismatched types
53-
5453
}

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