Use write_str() instead of write!() when possible

compiler/rustc_ast/src/util/literal.rs

@@ -210,7 +210,7 @@ impl fmt::Display for LitKind {
             LitKind::Err => {
                 // This only shows up in places like `-Zunpretty=hir` output, so we
                 // don't bother to produce something useful.
-                write!(f, "<bad-literal>")?;
+                f.write_str("<bad-literal>")?;
             }
         }
 

compiler/rustc_const_eval/src/const_eval/error.rs

@@ -37,9 +37,9 @@ impl fmt::Display for ConstEvalErrKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         use self::ConstEvalErrKind::*;
         match self {
-            ConstAccessesStatic => write!(f, "constant accesses static"),
+            ConstAccessesStatic => f.write_str("constant accesses static"),
             ModifiedGlobal => {
-                write!(f, "modifying a static's initial value from another static's initializer")
+                f.write_str("modifying a static's initial value from another static's initializer")
             }
             AssertFailure(msg) => write!(f, "{:?}", msg),
             Panic { msg, line, col, file } => {

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -147,7 +147,7 @@ pub enum MemoryKind {
 impl fmt::Display for MemoryKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            MemoryKind::Heap => write!(f, "heap allocation"),
+            MemoryKind::Heap => f.write_str("heap allocation"),
         }
     }
 }

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -265,7 +265,7 @@ impl<'tcx> fmt::Display for FrameInfo<'tcx> {
             if tcx.def_key(self.instance.def_id()).disambiguated_data.data
                 == DefPathData::ClosureExpr
             {
-                write!(f, "inside closure")
+                f.write_str("inside closure")
             } else {
                 // Note: this triggers a `good_path_bug` state, which means that if we ever get here
                 // we must emit a diagnostic. We should never display a `FrameInfo` unless we
@@ -987,12 +987,12 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> std::fmt::Debug
                 if frame != self.ecx.frame_idx() {
                     write!(fmt, " ({} frames up)", self.ecx.frame_idx() - frame)?;
                 }
-                write!(fmt, ":")?;
+                fmt.write_str(":")?;
 
                 match self.ecx.stack()[frame].locals[local].value {
-                    LocalValue::Dead => write!(fmt, " is dead")?,
+                    LocalValue::Dead => fmt.write_str(" is dead")?,
                     LocalValue::Live(Operand::Immediate(Immediate::Uninit)) => {
-                        write!(fmt, " is uninitialized")?
+                        fmt.write_str(" is uninitialized")?
                     }
                     LocalValue::Live(Operand::Indirect(mplace)) => {
                         write!(

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -50,8 +50,8 @@ impl<T: MayLeak> MayLeak for MemoryKind<T> {
 impl<T: fmt::Display> fmt::Display for MemoryKind<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            MemoryKind::Stack => write!(f, "stack variable"),
-            MemoryKind::CallerLocation => write!(f, "caller location"),
+            MemoryKind::Stack => f.write_str("stack variable"),
+            MemoryKind::CallerLocation => f.write_str("caller location"),
             MemoryKind::Machine(m) => write!(f, "{}", m),
         }
     }
@@ -893,7 +893,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> std::fmt::Debug for DumpAllocs<'a,
                     // global alloc
                     match self.ecx.tcx.try_get_global_alloc(id) {
                         Some(GlobalAlloc::Memory(alloc)) => {
-                            write!(fmt, " (unchanged global, ")?;
+                            fmt.write_str(" (unchanged global, ")?;
                             write_allocation_track_relocs(
                                 &mut *fmt,
                                 *self.ecx.tcx,
@@ -914,7 +914,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> std::fmt::Debug for DumpAllocs<'a,
                             write!(fmt, " (static: {})", self.ecx.tcx.def_path_str(did))?;
                         }
                         None => {
-                            write!(fmt, " (deallocated)")?;
+                            fmt.write_str(" (deallocated)")?;
                         }
                     }
                 }

compiler/rustc_driver_impl/src/args.rs

@@ -41,7 +41,7 @@ pub enum Error {
 impl fmt::Display for Error {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Error::Utf8Error(None) => write!(fmt, "Utf8 error"),
+            Error::Utf8Error(None) => fmt.write_str("Utf8 error"),
             Error::Utf8Error(Some(path)) => write!(fmt, "Utf8 error in {path}"),
             Error::IOError(path, err) => write!(fmt, "IO Error: {path}: {err}"),
         }

compiler/rustc_error_messages/src/lib.rs

@@ -74,15 +74,15 @@ impl fmt::Display for TranslationBundleError {
                 write!(f, "could not parse ftl file: {}", e)
             }
             TranslationBundleError::AddResource(e) => write!(f, "failed to add resource: {}", e),
-            TranslationBundleError::MissingLocale => write!(f, "missing locale directory"),
+            TranslationBundleError::MissingLocale => f.write_str("missing locale directory"),
             TranslationBundleError::ReadLocalesDir(e) => {
                 write!(f, "could not read locales dir: {}", e)
             }
             TranslationBundleError::ReadLocalesDirEntry(e) => {
                 write!(f, "could not read locales dir entry: {}", e)
             }
             TranslationBundleError::LocaleIsNotDir => {
-                write!(f, "`$sysroot/share/locales/$locale` is not a directory")
+                f.write_str("`$sysroot/share/locales/$locale` is not a directory")
             }
         }
     }

compiler/rustc_expand/src/mbe/macro_parser.rs

@@ -157,7 +157,7 @@ impl Display for MatcherLoc {
                 if let Some(kind) = kind {
                     write!(f, ":{}", kind)?;
                 }
-                write!(f, "`")?;
+                f.write_str("`")?;
                 Ok(())
             }
             MatcherLoc::Eof => f.write_str("end of macro"),

compiler/rustc_feature/src/builtin_attrs.rs

@@ -72,7 +72,7 @@ impl std::fmt::Debug for AttributeGate {
             Self::Gated(ref stab, name, expl, _) => {
                 write!(fmt, "Gated({stab:?}, {name}, {expl})")
             }
-            Self::Ungated => write!(fmt, "Ungated"),
+            Self::Ungated => fmt.write_str("Ungated"),
         }
     }
 }

compiler/rustc_feature/src/lib.rs

@@ -38,10 +38,10 @@ pub enum State {
 impl fmt::Debug for State {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            State::Accepted { .. } => write!(f, "accepted"),
-            State::Active { .. } => write!(f, "active"),
-            State::Removed { .. } => write!(f, "removed"),
-            State::Stabilized { .. } => write!(f, "stabilized"),
+            State::Accepted { .. } => f.write_str("accepted"),
+            State::Active { .. } => f.write_str("active"),
+            State::Removed { .. } => f.write_str("removed"),
+            State::Stabilized { .. } => f.write_str("stabilized"),
         }
     }
 }

compiler/rustc_hir/src/hir.rs

@@ -1620,9 +1620,9 @@ impl ConstContext {
 impl fmt::Display for ConstContext {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
-            Self::Const => write!(f, "constant"),
-            Self::Static(_) => write!(f, "static"),
-            Self::ConstFn => write!(f, "constant function"),
+            Self::Const => f.write_str("constant"),
+            Self::Static(_) => f.write_str("static"),
+            Self::ConstFn => f.write_str("constant function"),
         }
     }
 }

compiler/rustc_infer/src/infer/mod.rs

@@ -531,8 +531,8 @@ impl<'tcx> fmt::Display for FixupError<'tcx> {
                 "cannot determine the type of this number; \
                  add a suffix to specify the type explicitly"
             ),
-            UnresolvedTy(_) => write!(f, "unconstrained type"),
-            UnresolvedConst(_) => write!(f, "unconstrained const value"),
+            UnresolvedTy(_) => f.write_str("unconstrained type"),
+            UnresolvedConst(_) => f.write_str("unconstrained const value"),
         }
     }
 }

compiler/rustc_infer/src/infer/region_constraints/mod.rs

@@ -702,7 +702,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
 
 impl fmt::Debug for RegionSnapshot {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "RegionSnapshot")
+        f.write_str("RegionSnapshot")
     }
 }
 

compiler/rustc_infer/src/traits/structural_impls.rs

@@ -46,7 +46,7 @@ impl<'tcx> fmt::Debug for traits::FulfillmentErrorCode<'tcx> {
             super::CodeConstEquateError(ref a, ref b) => {
                 write!(f, "CodeConstEquateError({:?}, {:?})", a, b)
             }
-            super::CodeAmbiguity => write!(f, "Ambiguity"),
+            super::CodeAmbiguity => f.write_str("Ambiguity"),
             super::CodeCycle(ref cycle) => write!(f, "Cycle({:?})", cycle),
         }
     }

compiler/rustc_interface/src/callbacks.rs

@@ -56,7 +56,7 @@ fn def_id_debug(def_id: rustc_hir::def_id::DefId, f: &mut fmt::Formatter<'_>) ->
         }
         Ok(())
     })?;
-    write!(f, ")")
+    f.write_str(")")
 }
 
 /// Sets up the callbacks in prior crates which we want to refer to the

compiler/rustc_macros/src/diagnostics/utils.rs

@@ -516,11 +516,11 @@ impl FromStr for SuggestionKind {
 impl fmt::Display for SuggestionKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            SuggestionKind::Normal => write!(f, "normal"),
-            SuggestionKind::Short => write!(f, "short"),
-            SuggestionKind::Hidden => write!(f, "hidden"),
-            SuggestionKind::Verbose => write!(f, "verbose"),
-            SuggestionKind::ToolOnly => write!(f, "tool-only"),
+            SuggestionKind::Normal => f.write_str("normal"),
+            SuggestionKind::Short => f.write_str("short"),
+            SuggestionKind::Hidden => f.write_str("hidden"),
+            SuggestionKind::Verbose => f.write_str("verbose"),
+            SuggestionKind::ToolOnly => f.write_str("tool-only"),
         }
     }
 }
@@ -822,13 +822,13 @@ impl SubdiagnosticKind {
 impl quote::IdentFragment for SubdiagnosticKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            SubdiagnosticKind::Label => write!(f, "label"),
-            SubdiagnosticKind::Note => write!(f, "note"),
-            SubdiagnosticKind::Help => write!(f, "help"),
-            SubdiagnosticKind::Warn => write!(f, "warn"),
-            SubdiagnosticKind::Suggestion { .. } => write!(f, "suggestions_with_style"),
+            SubdiagnosticKind::Label => f.write_str("label"),
+            SubdiagnosticKind::Note => f.write_str("note"),
+            SubdiagnosticKind::Help => f.write_str("help"),
+            SubdiagnosticKind::Warn => f.write_str("warn"),
+            SubdiagnosticKind::Suggestion { .. } => f.write_str("suggestions_with_style"),
             SubdiagnosticKind::MultipartSuggestion { .. } => {
-                write!(f, "multipart_suggestion_with_style")
+                f.write_str("multipart_suggestion_with_style")
             }
         }
     }

compiler/rustc_middle/src/dep_graph/mod.rs

@@ -45,7 +45,7 @@ impl rustc_query_system::dep_graph::DepKind for DepKind {
             Ok(())
         })?;
 
-        write!(f, ")")
+        f.write_str(")")
     }
 
     fn with_deps<OP, R>(task_deps: TaskDepsRef<'_>, op: OP) -> R

compiler/rustc_middle/src/mir/coverage.rs

@@ -141,7 +141,7 @@ impl Debug for CoverageKind {
                 },
                 rhs.index(),
             ),
-            Unreachable => write!(fmt, "Unreachable"),
+            Unreachable => fmt.write_str("Unreachable"),
         }
     }
 }

compiler/rustc_middle/src/mir/interpret/allocation.rs

@@ -150,7 +150,7 @@ impl<'tcx> fmt::Debug for ConstAllocation<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // The debug representation of this is very verbose and basically useless,
         // so don't print it.
-        write!(f, "ConstAllocation {{ .. }}")
+        f.write_str("ConstAllocation { .. }")
     }
 }
 

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -140,7 +140,7 @@ impl fmt::Display for InvalidProgramInfo<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         use InvalidProgramInfo::*;
         match self {
-            TooGeneric => write!(f, "encountered overly generic constant"),
+            TooGeneric => f.write_str("encountered overly generic constant"),
             AlreadyReported(ErrorGuaranteed { .. }) => {
                 write!(
                     f,
@@ -288,15 +288,15 @@ impl fmt::Display for UndefinedBehaviorInfo {
         use UndefinedBehaviorInfo::*;
         match self {
             Ub(msg) => write!(f, "{msg}"),
-            Unreachable => write!(f, "entering unreachable code"),
+            Unreachable => f.write_str("entering unreachable code"),
             BoundsCheckFailed { ref len, ref index } => {
                 write!(f, "indexing out of bounds: the len is {len} but the index is {index}")
             }
-            DivisionByZero => write!(f, "dividing by zero"),
-            RemainderByZero => write!(f, "calculating the remainder with a divisor of zero"),
-            DivisionOverflow => write!(f, "overflow in signed division (dividing MIN by -1)"),
-            RemainderOverflow => write!(f, "overflow in signed remainder (dividing MIN by -1)"),
-            PointerArithOverflow => write!(f, "overflowing in-bounds pointer arithmetic"),
+            DivisionByZero => f.write_str("dividing by zero"),
+            RemainderByZero => f.write_str("calculating the remainder with a divisor of zero"),
+            DivisionOverflow => f.write_str("overflow in signed division (dividing MIN by -1)"),
+            RemainderOverflow => f.write_str("overflow in signed remainder (dividing MIN by -1)"),
+            PointerArithOverflow => f.write_str("overflowing in-bounds pointer arithmetic"),
             InvalidMeta(msg) => write!(f, "invalid metadata in wide pointer: {msg}"),
             UnterminatedCString(p) => write!(
                 f,
@@ -367,13 +367,13 @@ impl fmt::Display for UndefinedBehaviorInfo {
                 f,
                 "using uninitialized data, but this operation requires initialized memory"
             ),
-            DeadLocal => write!(f, "accessing a dead local variable"),
+            DeadLocal => f.write_str("accessing a dead local variable"),
             ScalarSizeMismatch(self::ScalarSizeMismatch { target_size, data_size }) => write!(
                 f,
                 "scalar size mismatch: expected {target_size} bytes but got {data_size} bytes instead",
             ),
             UninhabitedEnumVariantWritten => {
-                write!(f, "writing discriminant of an uninhabited enum")
+                f.write_str("writing discriminant of an uninhabited enum")
             }
         }
     }
@@ -414,7 +414,7 @@ impl fmt::Display for UnsupportedOpInfo {
             PartialPointerCopy(ptr) => {
                 write!(f, "unable to copy parts of a pointer from memory at {ptr:?}")
             }
-            ReadPointerAsBytes => write!(f, "unable to turn pointer into raw bytes"),
+            ReadPointerAsBytes => f.write_str("unable to turn pointer into raw bytes"),
             ThreadLocalStatic(did) => write!(f, "cannot access thread local static ({did:?})"),
             ReadExternStatic(did) => write!(f, "cannot read from extern static ({did:?})"),
         }
@@ -441,16 +441,16 @@ impl fmt::Display for ResourceExhaustionInfo {
         use ResourceExhaustionInfo::*;
         match self {
             StackFrameLimitReached => {
-                write!(f, "reached the configured maximum number of stack frames")
+                f.write_str("reached the configured maximum number of stack frames")
             }
             StepLimitReached => {
-                write!(f, "exceeded interpreter step limit (see `#[const_eval_limit]`)")
+                f.write_str("exceeded interpreter step limit (see `#[const_eval_limit]`)")
             }
             MemoryExhausted => {
-                write!(f, "tried to allocate more memory than available to compiler")
+                f.write_str("tried to allocate more memory than available to compiler")
             }
             AddressSpaceFull => {
-                write!(f, "there are no more free addresses in the address space")
+                f.write_str("there are no more free addresses in the address space")
             }
         }
     }

compiler/rustc_middle/src/mir/interpret/pointer.rs

@@ -204,7 +204,7 @@ impl<Prov: Provenance> fmt::Debug for Pointer<Option<Prov>> {
 impl<Prov: Provenance> fmt::Display for Pointer<Option<Prov>> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if self.provenance.is_none() && self.offset.bytes() == 0 {
-            write!(f, "null pointer")
+            f.write_str("null pointer")
         } else {
             fmt::Debug::fmt(self, f)
         }