Rollup merge of rust-lang#131942 - workingjubilee:reduce-haruspicy, r=lukas-code,lnicola

compiler: Adopt rust-analyzer impls for `LayoutCalculatorError`

We're about to massively churn the internals of `rustc_abi`. To minimize the immediate and future impact on rust-analyzer, as a subtree that depends on this crate, grow some API on `LayoutCalculatorError` that reflects their uses of it. This way we can nest the type in theirs, and they can just call functions on it without having to inspect and flatten-out its innards.

Author: Zalathar

compiler/rustc_abi/src/layout.rs

@@ -39,7 +39,7 @@ enum NicheBias {
     End,
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum LayoutCalculatorError<F> {
     /// An unsized type was found in a location where a sized type was expected.
     ///
@@ -56,6 +56,31 @@ pub enum LayoutCalculatorError<F> {
     EmptyUnion,
 }
 
+impl<F> LayoutCalculatorError<F> {
+    pub fn without_payload(&self) -> LayoutCalculatorError<()> {
+        match self {
+            LayoutCalculatorError::UnexpectedUnsized(_) => {
+                LayoutCalculatorError::UnexpectedUnsized(())
+            }
+            LayoutCalculatorError::SizeOverflow => LayoutCalculatorError::SizeOverflow,
+            LayoutCalculatorError::EmptyUnion => LayoutCalculatorError::EmptyUnion,
+        }
+    }
+
+    /// Format an untranslated diagnostic for this type
+    ///
+    /// Intended for use by rust-analyzer, as neither it nor `rustc_abi` depend on fluent infra.
+    pub fn fallback_fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(match self {
+            LayoutCalculatorError::UnexpectedUnsized(_) => {
+                "an unsized type was found where a sized type was expected"
+            }
+            LayoutCalculatorError::SizeOverflow => "size overflow",
+            LayoutCalculatorError::EmptyUnion => "type is a union with no fields",
+        })
+    }
+}
+
 type LayoutCalculatorResult<FieldIdx, VariantIdx, F> =
     Result<LayoutS<FieldIdx, VariantIdx>, LayoutCalculatorError<F>>;
 

src/tools/rust-analyzer/crates/hir-ty/src/layout.rs

@@ -72,6 +72,8 @@ pub type Variants = hir_def::layout::Variants<RustcFieldIdx, RustcEnumVariantIdx
 
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub enum LayoutError {
+    // FIXME: Remove variants that duplicate LayoutCalculatorError's variants after sync
+    BadCalc(LayoutCalculatorError<()>),
     EmptyUnion,
     HasErrorConst,
     HasErrorType,
@@ -90,6 +92,7 @@ impl std::error::Error for LayoutError {}
 impl fmt::Display for LayoutError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
+            LayoutError::BadCalc(err) => err.fallback_fmt(f),
             LayoutError::EmptyUnion => write!(f, "type is an union with no fields"),
             LayoutError::HasErrorConst => write!(f, "type contains an unevaluatable const"),
             LayoutError::HasErrorType => write!(f, "type contains an error"),
@@ -114,11 +117,7 @@ impl fmt::Display for LayoutError {
 
 impl<F> From<LayoutCalculatorError<F>> for LayoutError {
     fn from(err: LayoutCalculatorError<F>) -> Self {
-        match err {
-            LayoutCalculatorError::EmptyUnion => LayoutError::EmptyUnion,
-            LayoutCalculatorError::UnexpectedUnsized(_) => LayoutError::UnexpectedUnsized,
-            LayoutCalculatorError::SizeOverflow => LayoutError::SizeOverflow,
-        }
+        LayoutError::BadCalc(err.without_payload())
     }
 }