diff --git a/compiler/rustc_driver/src/args.rs b/compiler/rustc_driver/src/args.rs index 5686819c61b..4f2febf04b1 100644 --- a/compiler/rustc_driver/src/args.rs +++ b/compiler/rustc_driver/src/args.rs @@ -4,8 +4,7 @@ use std::fs; use std::io; pub fn arg_expand(arg: String) -> Result, Error> { - if arg.starts_with('@') { - let path = &arg[1..]; + if let Some(path) = arg.strip_prefix('@') { let file = match fs::read_to_string(path) { Ok(file) => file, Err(ref err) if err.kind() == io::ErrorKind::InvalidData => { diff --git a/compiler/rustc_mir/src/borrow_check/diagnostics/move_errors.rs b/compiler/rustc_mir/src/borrow_check/diagnostics/move_errors.rs index e256fb55b12..629e9be9ddd 100644 --- a/compiler/rustc_mir/src/borrow_check/diagnostics/move_errors.rs +++ b/compiler/rustc_mir/src/borrow_check/diagnostics/move_errors.rs @@ -492,8 +492,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { { if let Ok(pat_snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(pat_span) { - if pat_snippet.starts_with('&') { - let pat_snippet = pat_snippet[1..].trim_start(); + if let Some(stripped) = pat_snippet.strip_prefix('&') { + let pat_snippet = stripped.trim_start(); let (suggestion, to_remove) = if pat_snippet.starts_with("mut") && pat_snippet["mut".len()..].starts_with(rustc_lexer::is_whitespace) { diff --git a/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs b/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs index 8b0121cf360..d4cdf02104a 100644 --- a/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs +++ b/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs @@ -631,9 +631,8 @@ fn suggest_ampmut<'tcx>( let lt_name = &src[1..ws_pos]; let ty = &src[ws_pos..]; return (assignment_rhs_span, format!("&{} mut {}", lt_name, ty)); - } else if src.starts_with('&') { - let borrowed_expr = &src[1..]; - return (assignment_rhs_span, format!("&mut {}", borrowed_expr)); + } else if let Some(stripped) = src.strip_prefix('&') { + return (assignment_rhs_span, format!("&mut {}", stripped)); } } } diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs index 2cc87dc6375..ced272e474d 100644 --- a/compiler/rustc_resolve/src/late/diagnostics.rs +++ b/compiler/rustc_resolve/src/late/diagnostics.rs @@ -1418,9 +1418,9 @@ impl<'tcx> LifetimeContext<'_, 'tcx> { if snippet.starts_with('&') && !snippet.starts_with("&'") { introduce_suggestion .push((param.span, format!("&{} {}", lt_name, &snippet[1..]))); - } else if snippet.starts_with("&'_ ") { + } else if let Some(stripped) = snippet.strip_prefix("&'_ ") { introduce_suggestion - .push((param.span, format!("&{} {}", lt_name, &snippet[4..]))); + .push((param.span, format!("&{} {}", lt_name, stripped))); } } } diff --git a/compiler/rustc_session/src/search_paths.rs b/compiler/rustc_session/src/search_paths.rs index e12364b7dac..83b737a73b1 100644 --- a/compiler/rustc_session/src/search_paths.rs +++ b/compiler/rustc_session/src/search_paths.rs @@ -56,16 +56,16 @@ impl PathKind { impl SearchPath { pub fn from_cli_opt(path: &str, output: config::ErrorOutputType) -> Self { - let (kind, path) = if path.starts_with("native=") { - (PathKind::Native, &path["native=".len()..]) - } else if path.starts_with("crate=") { - (PathKind::Crate, &path["crate=".len()..]) - } else if path.starts_with("dependency=") { - (PathKind::Dependency, &path["dependency=".len()..]) - } else if path.starts_with("framework=") { - (PathKind::Framework, &path["framework=".len()..]) - } else if path.starts_with("all=") { - (PathKind::All, &path["all=".len()..]) + let (kind, path) = if let Some(stripped) = path.strip_prefix("native=") { + (PathKind::Native, stripped) + } else if let Some(stripped) = path.strip_prefix("crate=") { + (PathKind::Crate, stripped) + } else if let Some(stripped) = path.strip_prefix("dependency=") { + (PathKind::Dependency, stripped) + } else if let Some(stripped) = path.strip_prefix("framework=") { + (PathKind::Framework, stripped) + } else if let Some(stripped) = path.strip_prefix("all=") { + (PathKind::All, stripped) } else { (PathKind::All, path) }; diff --git a/compiler/rustc_typeck/src/check/demand.rs b/compiler/rustc_typeck/src/check/demand.rs index f6b768bb122..c7ce5008c33 100644 --- a/compiler/rustc_typeck/src/check/demand.rs +++ b/compiler/rustc_typeck/src/check/demand.rs @@ -370,7 +370,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { { let s = s.as_ref(); let old = old.as_ref(); - if s.starts_with(old) { Some(new.as_ref().to_owned() + &s[old.len()..]) } else { None } + if let Some(stripped) = s.strip_prefix(old) { + Some(new.as_ref().to_owned() + stripped) + } else { + None + } } /// This function is used to determine potential "simple" improvements or users' errors and diff --git a/compiler/rustc_typeck/src/check/op.rs b/compiler/rustc_typeck/src/check/op.rs index 529b8525a4a..66975f32a1f 100644 --- a/compiler/rustc_typeck/src/check/op.rs +++ b/compiler/rustc_typeck/src/check/op.rs @@ -589,10 +589,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } else { msg }, - if lstring.starts_with('&') { + if let Some(stripped) = lstring.strip_prefix('&') { // let a = String::new(); // let _ = &a + "bar"; - lstring[1..].to_string() + stripped.to_string() } else { format!("{}.to_owned()", lstring) }, @@ -617,10 +617,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { is_assign, ) { (Ok(l), Ok(r), IsAssign::No) => { - let to_string = if l.starts_with('&') { + let to_string = if let Some(stripped) = l.strip_prefix('&') { // let a = String::new(); let b = String::new(); // let _ = &a + b; - l[1..].to_string() + stripped.to_string() } else { format!("{}.to_owned()", l) }; diff --git a/compiler/rustc_typeck/src/collect.rs b/compiler/rustc_typeck/src/collect.rs index 9b8427a4695..504b5a330f0 100644 --- a/compiler/rustc_typeck/src/collect.rs +++ b/compiler/rustc_typeck/src/collect.rs @@ -2341,8 +2341,8 @@ fn from_target_feature( item.span(), format!("`{}` is not valid for this target", feature), ); - if feature.starts_with('+') { - let valid = supported_target_features.contains_key(&feature[1..]); + if let Some(stripped) = feature.strip_prefix('+') { + let valid = supported_target_features.contains_key(stripped); if valid { err.help("consider removing the leading `+` in the feature name"); }