Change some matches!(.., .. if ..) with let-chains

Author: estebank

compiler/rustc_const_eval/src/check_consts/check.rs

@@ -833,12 +833,13 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
 
                 // const-eval of `panic_display` assumes the argument is `&&str`
                 if tcx.is_lang_item(callee, LangItem::PanicDisplay) {
-                    match args[0].node.ty(&self.ccx.body.local_decls, tcx).kind() {
-                        ty::Ref(_, ty, _) if matches!(ty.kind(), ty::Ref(_, ty, _) if ty.is_str()) =>
-                            {}
-                        _ => {
-                            self.check_op(ops::PanicNonStr);
-                        }
+                    if let ty::Ref(_, ty, _) =
+                        args[0].node.ty(&self.ccx.body.local_decls, tcx).kind()
+                        && let ty::Ref(_, ty, _) = ty.kind()
+                        && ty.is_str()
+                    {
+                    } else {
+                        self.check_op(ops::PanicNonStr);
                     }
                     // Allow this call, skip all the checks below.
                     return;

compiler/rustc_lint/src/early/diagnostics/check_cfg.rs

@@ -70,7 +70,7 @@ fn cargo_help_sub(
     // `build_script_build`) to try to figure out if we are building a Cargo build script
 
     let unescaped = &inst(EscapeQuotes::No);
-    if matches!(&sess.opts.crate_name, Some(crate_name) if crate_name == "build_script_build") {
+    if let Some("build_script_build") = sess.opts.crate_name.as_deref() {
         lints::UnexpectedCfgCargoHelp::lint_cfg(unescaped)
     } else {
         lints::UnexpectedCfgCargoHelp::lint_cfg_and_build_rs(unescaped, &inst(EscapeQuotes::Yes))

compiler/rustc_lint/src/transmute.rs

@@ -152,7 +152,9 @@ fn check_int_to_ptr_transmute<'tcx>(
         return;
     };
     // bail-out if the argument is literal 0 as we have other lints for those cases
-    if matches!(arg.kind, hir::ExprKind::Lit(hir::Lit { node: LitKind::Int(v, _), .. }) if v == 0) {
+    if let hir::ExprKind::Lit(hir::Lit { node: LitKind::Int(v, _), .. }) = arg.kind
+        && v == 0
+    {
         return;
     }
     // bail-out if the inner type is a ZST

compiler/rustc_middle/src/mir/pretty.rs

@@ -1871,13 +1871,16 @@ fn pretty_print_const_value_tcx<'tcx>(
     let u8_type = tcx.types.u8;
     match (ct, ty.kind()) {
         // Byte/string slices, printed as (byte) string literals.
-        (_, ty::Ref(_, inner_ty, _)) if matches!(inner_ty.kind(), ty::Str) => {
+        (_, ty::Ref(_, inner_ty, _)) if let ty::Str = inner_ty.kind() => {
             if let Some(data) = ct.try_get_slice_bytes_for_diagnostics(tcx) {
                 fmt.write_str(&format!("{:?}", String::from_utf8_lossy(data)))?;
                 return Ok(());
             }
         }
-        (_, ty::Ref(_, inner_ty, _)) if matches!(inner_ty.kind(), ty::Slice(t) if *t == u8_type) => {
+        (_, ty::Ref(_, inner_ty, _))
+            if let ty::Slice(t) = inner_ty.kind()
+                && *t == u8_type =>
+        {
             if let Some(data) = ct.try_get_slice_bytes_for_diagnostics(tcx) {
                 pretty_print_byte_str(fmt, data)?;
                 return Ok(());

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -761,7 +761,9 @@ impl<'a> Parser<'a> {
         }
 
         // Check for misspelled keywords if there are no suggestions added to the diagnostic.
-        if matches!(&err.suggestions, Suggestions::Enabled(list) if list.is_empty()) {
+        if let Suggestions::Enabled(list) = &err.suggestions
+            && list.is_empty()
+        {
             self.check_for_misspelled_kw(&mut err, &expected);
         }
         Err(err)

compiler/rustc_parse/src/parser/mod.rs

@@ -1203,10 +1203,9 @@ impl<'a> Parser<'a> {
         let mut token = Token::dummy();
         while i < dist {
             token = cursor.next().0;
-            if matches!(
-                token.kind,
-                token::OpenInvisible(origin) | token::CloseInvisible(origin) if origin.skip()
-            ) {
+            if let token::OpenInvisible(origin) | token::CloseInvisible(origin) = token.kind
+                && origin.skip()
+            {
                 continue;
             }
             i += 1;

compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs

@@ -4691,7 +4691,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         // slices of `element_ty` with `mutability`.
         let mut is_slice = |candidate: Ty<'tcx>| match *candidate.kind() {
             ty::RawPtr(t, m) | ty::Ref(_, t, m) => {
-                if matches!(*t.kind(), ty::Slice(e) if e == element_ty)
+                if let ty::Slice(e) = *t.kind()
+                    && e == element_ty
                     && m == mutability.unwrap_or(m)
                 {
                     // Use the candidate's mutability going forward.