Rollup of 5 pull requests

Cargo.lock

@@ -1556,16 +1556,6 @@ version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "42703706b716c37f96a77aea830392ad231f44c9e9a67872fa5548707e11b11c"
 
-[[package]]
-name = "futf"
-version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "df420e2e84819663797d1ec6544b13c5be84629e7bb00dc960d6917db2987843"
-dependencies = [
- "mac",
- "new_debug_unreachable",
-]
-
 [[package]]
 name = "generate-copyright"
 version = "0.1.0"
@@ -1791,14 +1781,12 @@ dependencies = [
 
 [[package]]
 name = "html5ever"
-version = "0.29.1"
+version = "0.39.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b7410cae13cbc75623c98ac4cbfd1f0bedddf3227afc24f370cf0f50a44a11c"
+checksum = "46a1761807faccc9a19e86944bbf40610014066306f96edcdedc2fb714bcb7b8"
 dependencies = [
  "log",
- "mac",
  "markup5ever",
- "match_token",
 ]
 
 [[package]]
@@ -2424,35 +2412,15 @@ dependencies = [
  "pkg-config",
 ]
 
-[[package]]
-name = "mac"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c41e0c4fef86961ac6d6f8a82609f55f31b05e4fce149ac5710e439df7619ba4"
-
 [[package]]
 name = "markup5ever"
-version = "0.14.1"
+version = "0.39.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7a7213d12e1864c0f002f52c2923d4556935a43dec5e71355c2760e0f6e7a18"
+checksum = "7122d987ec5f704ee56f6e5b41a7d93722e9aae27ae07cafa4036c4d3f9757de"
 dependencies = [
  "log",
- "phf 0.11.3",
- "phf_codegen",
- "string_cache",
- "string_cache_codegen",
  "tendril",
-]
-
-[[package]]
-name = "match_token"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "88a9689d8d44bf9964484516275f5cd4c9b59457a6940c1d5d0ecbb94510a36b"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
+ "web_atoms",
 ]
 
 [[package]]
@@ -2986,56 +2954,57 @@ dependencies = [
 
 [[package]]
 name = "phf"
-version = "0.11.3"
+version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1fd6780a80ae0c52cc120a26a1a42c1ae51b247a253e4e06113d23d2c2edd078"
+checksum = "913273894cec178f401a31ec4b656318d95473527be05c0752cc41cdc32be8b7"
 dependencies = [
- "phf_shared 0.11.3",
+ "phf_shared 0.12.1",
 ]
 
 [[package]]
 name = "phf"
-version = "0.12.1"
+version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "913273894cec178f401a31ec4b656318d95473527be05c0752cc41cdc32be8b7"
+checksum = "c1562dc717473dbaa4c1f85a36410e03c047b2e7df7f45ee938fbef64ae7fadf"
 dependencies = [
- "phf_shared 0.12.1",
+ "phf_shared 0.13.1",
+ "serde",
 ]
 
 [[package]]
 name = "phf_codegen"
-version = "0.11.3"
+version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aef8048c789fa5e851558d709946d6d79a8ff88c0440c587967f8e94bfb1216a"
+checksum = "49aa7f9d80421bca176ca8dbfebe668cc7a2684708594ec9f3c0db0805d5d6e1"
 dependencies = [
  "phf_generator",
- "phf_shared 0.11.3",
+ "phf_shared 0.13.1",
 ]
 
 [[package]]
 name = "phf_generator"
-version = "0.11.3"
+version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c80231409c20246a13fddb31776fb942c38553c51e871f8cbd687a4cfb5843d"
+checksum = "135ace3a761e564ec88c03a77317a7c6b80bb7f7135ef2544dbe054243b89737"
 dependencies = [
- "phf_shared 0.11.3",
- "rand 0.8.5",
+ "fastrand",
+ "phf_shared 0.13.1",
 ]
 
 [[package]]
 name = "phf_shared"
-version = "0.11.3"
+version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "67eabc2ef2a60eb7faa00097bd1ffdb5bd28e62bf39990626a582201b7a754e5"
+checksum = "06005508882fb681fd97892ecff4b7fd0fee13ef1aa569f8695dae7ab9099981"
 dependencies = [
  "siphasher",
 ]
 
 [[package]]
 name = "phf_shared"
-version = "0.12.1"
+version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "06005508882fb681fd97892ecff4b7fd0fee13ef1aa569f8695dae7ab9099981"
+checksum = "e57fef6bc5981e38c2ce2d63bfa546861309f875b8a75f092d1d54ae2d64f266"
 dependencies = [
  "siphasher",
 ]
@@ -5425,25 +5394,24 @@ checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
 
 [[package]]
 name = "string_cache"
-version = "0.8.9"
+version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bf776ba3fa74f83bf4b63c3dcbbf82173db2632ed8452cb2d891d33f459de70f"
+checksum = "a18596f8c785a729f2819c0f6a7eae6ebeebdfffbfe4214ae6b087f690e31901"
 dependencies = [
  "new_debug_unreachable",
  "parking_lot",
- "phf_shared 0.11.3",
+ "phf_shared 0.13.1",
  "precomputed-hash",
- "serde",
 ]
 
 [[package]]
 name = "string_cache_codegen"
-version = "0.5.4"
+version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c711928715f1fe0fe509c53b43e993a9a557babc2d0a3567d0a3006f1ac931a0"
+checksum = "585635e46db231059f76c5849798146164652513eb9e8ab2685939dd90f29b69"
 dependencies = [
  "phf_generator",
- "phf_shared 0.11.3",
+ "phf_shared 0.13.1",
  "proc-macro2",
  "quote",
 ]
@@ -5533,12 +5501,11 @@ dependencies = [
 
 [[package]]
 name = "tendril"
-version = "0.4.3"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d24a120c5fc464a3458240ee02c299ebcb9d67b5249c8848b09d639dca8d7bb0"
+checksum = "c4790fc369d5a530f4b544b094e31388b9b3a37c0f4652ade4505945f5660d24"
 dependencies = [
- "futf",
- "mac",
+ "new_debug_unreachable",
  "utf-8",
 ]
 
@@ -6503,6 +6470,18 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "web_atoms"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "075474b12bcb3d2e3d4546580e9de478eeeead668a1761e2a8860c836b7ef297"
+dependencies = [
+ "phf 0.13.1",
+ "phf_codegen",
+ "string_cache",
+ "string_cache_codegen",
+]
+
 [[package]]
 name = "winapi-util"
 version = "0.1.11"

compiler/rustc_abi/src/layout.rs

@@ -477,12 +477,14 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             Ok(Some((repr, _))) => match repr {
                 // Mismatched alignment (e.g. union is #[repr(packed)]): disable opt
                 BackendRepr::Scalar(_) | BackendRepr::ScalarPair(_, _)
-                    if repr.scalar_align(dl).unwrap() != align =>
+                    if repr.scalar_platform_align(dl).unwrap() != align =>
                 {
                     BackendRepr::Memory { sized: true }
                 }
                 // Vectors require at least element alignment, else disable the opt
-                BackendRepr::SimdVector { element, count: _ } if element.align(dl).abi > align => {
+                BackendRepr::SimdVector { element, count: _ }
+                    if element.default_align(dl).abi > align =>
+                {
                     BackendRepr::Memory { sized: true }
                 }
                 // the alignment tests passed and we can use this
@@ -986,7 +988,8 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                         // roundtripping pointers through ptrtoint/inttoptr.
                         (p @ Primitive::Pointer(_), i @ Primitive::Int(..))
                         | (i @ Primitive::Int(..), p @ Primitive::Pointer(_))
-                            if p.size(dl) == i.size(dl) && p.align(dl) == i.align(dl) =>
+                            if p.size(dl) == i.size(dl)
+                                && p.default_align(dl) == i.default_align(dl) =>
                         {
                             p
                         }

compiler/rustc_abi/src/layout/simple.rs

@@ -49,7 +49,7 @@ impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
     pub fn scalar<C: HasDataLayout>(cx: &C, scalar: Scalar) -> Self {
         let largest_niche = Niche::from_scalar(cx, Size::ZERO, scalar);
         let size = scalar.size(cx);
-        let align = scalar.align(cx);
+        let align = scalar.default_align(cx);
 
         let range = scalar.valid_range(cx);
 
@@ -90,8 +90,8 @@ impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
 
     pub fn scalar_pair<C: HasDataLayout>(cx: &C, a: Scalar, b: Scalar) -> Self {
         let dl = cx.data_layout();
-        let b_align = b.align(dl).abi;
-        let align = a.align(dl).abi.max(b_align).max(dl.aggregate_align);
+        let b_align = b.default_align(dl).abi;
+        let align = a.default_align(dl).abi.max(b_align).max(dl.aggregate_align);
         let b_offset = a.size(dl).align_to(b_align);
         let size = (b_offset + b.size(dl)).align_to(align);
 

compiler/rustc_abi/src/lib.rs

@@ -1404,7 +1404,11 @@ impl Primitive {
         }
     }
 
-    pub fn align<C: HasDataLayout>(self, cx: &C) -> AbiAlign {
+    /// The *platform-specific* ABI alignment of this primitive.
+    ///
+    /// This is the type alignment for the corresponding built-in.
+    /// In other contexts it might have different alignment.
+    pub fn default_align<C: HasDataLayout>(self, cx: &C) -> AbiAlign {
         use Primitive::*;
         let dl = cx.data_layout();
 
@@ -1579,8 +1583,12 @@ impl Scalar {
         }
     }
 
-    pub fn align(self, cx: &impl HasDataLayout) -> AbiAlign {
-        self.primitive().align(cx)
+    /// The *platform-specific* ABI alignment of this scalar.
+    ///
+    /// This is the type alignment for the corresponding built-in.
+    /// This is *not* necessarily the correct alignment for a type that has this `BackendRepr::Scalar`!
+    pub fn default_align(self, cx: &impl HasDataLayout) -> AbiAlign {
+        self.primitive().default_align(cx)
     }
 
     pub fn size(self, cx: &impl HasDataLayout) -> Size {
@@ -1792,6 +1800,14 @@ impl IntoDiagArg for NumScalableVectors {
 #[cfg_attr(feature = "nightly", derive(StableHash))]
 pub enum BackendRepr {
     Scalar(Scalar),
+    /// The data contained in this type can be entirely represented by two scalars.
+    /// The two scalars are listed in *memory* order, so the first is at offset zero
+    /// and the second at a non-zero offset.
+    /// These need not be `FieldIdx(0)` and `FieldIdx(1)`.
+    ///
+    /// As of June 2026 the offset to the second scalar is the size of the first
+    /// scalar rounded up to the platform alignment of the second scalar.
+    /// That may soon change, however; see MCP#1007.
     ScalarPair(Scalar, Scalar),
     SimdScalableVector {
         element: Scalar,
@@ -1857,10 +1873,16 @@ impl BackendRepr {
     /// The psABI alignment for a `Scalar` or `ScalarPair`
     ///
     /// `None` for other variants.
-    pub fn scalar_align<C: HasDataLayout>(&self, cx: &C) -> Option<Align> {
+    ///
+    /// It's unclear whether this is a meaningful operation, and MCP#1007 proposes changes.
+    /// You should generally be using the alignment of the place or the type,
+    /// not calculating something from the `Scalar`s.
+    pub fn scalar_platform_align<C: HasDataLayout>(&self, cx: &C) -> Option<Align> {
         match *self {
-            BackendRepr::Scalar(s) => Some(s.align(cx).abi),
-            BackendRepr::ScalarPair(s1, s2) => Some(s1.align(cx).max(s2.align(cx)).abi),
+            BackendRepr::Scalar(s) => Some(s.default_align(cx).abi),
+            BackendRepr::ScalarPair(s1, s2) => {
+                Some(s1.default_align(cx).max(s2.default_align(cx)).abi)
+            }
             // The align of a Vector can vary in surprising ways
             BackendRepr::SimdVector { .. }
             | BackendRepr::Memory { .. }
@@ -1877,9 +1899,9 @@ impl BackendRepr {
             BackendRepr::Scalar(s) => Some(s.size(cx)),
             // May have some padding between the pair.
             BackendRepr::ScalarPair(s1, s2) => {
-                let field2_offset = s1.size(cx).align_to(s2.align(cx).abi);
+                let field2_offset = s1.size(cx).align_to(s2.default_align(cx).abi);
                 let size = (field2_offset + s2.size(cx)).align_to(
-                    self.scalar_align(cx)
+                    self.scalar_platform_align(cx)
                         // We absolutely must have an answer here or everything is FUBAR.
                         .unwrap(),
                 );

compiler/rustc_codegen_cranelift/src/value_and_place.rs

@@ -56,7 +56,7 @@ fn codegen_field<'tcx>(
 }
 
 fn scalar_pair_calculate_b_offset(tcx: TyCtxt<'_>, a_scalar: Scalar, b_scalar: Scalar) -> Offset32 {
-    let b_offset = a_scalar.size(&tcx).align_to(b_scalar.align(&tcx).abi);
+    let b_offset = a_scalar.size(&tcx).align_to(b_scalar.default_align(&tcx).abi);
     Offset32::new(b_offset.bytes().try_into().unwrap())
 }
 

compiler/rustc_codegen_gcc/src/builder.rs

@@ -1065,7 +1065,7 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
                 },
             )
         } else if let abi::BackendRepr::ScalarPair(ref a, ref b) = place.layout.backend_repr {
-            let b_offset = a.size(self).align_to(b.align(self).abi);
+            let b_offset = a.size(self).align_to(b.default_align(self).abi);
 
             let mut load = |i, scalar: &abi::Scalar, align| {
                 let ptr = if i == 0 {

compiler/rustc_codegen_gcc/src/type_of.rs

@@ -325,7 +325,8 @@ impl<'tcx> LayoutGccExt<'tcx> for TyAndLayout<'tcx> {
             return cx.type_i1();
         }
 
-        let offset = if index == 0 { Size::ZERO } else { a.size(cx).align_to(b.align(cx).abi) };
+        let offset =
+            if index == 0 { Size::ZERO } else { a.size(cx).align_to(b.default_align(cx).abi) };
         self.scalar_gcc_type_at(cx, scalar, offset)
     }
 

compiler/rustc_codegen_llvm/src/builder.rs

@@ -794,7 +794,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
             });
             OperandValue::Immediate(llval)
         } else if let abi::BackendRepr::ScalarPair(a, b) = place.layout.backend_repr {
-            let b_offset = a.size(self).align_to(b.align(self).abi);
+            let b_offset = a.size(self).align_to(b.default_align(self).abi);
 
             let mut load = |i, scalar: abi::Scalar, layout, align, offset| {
                 let llptr = if i == 0 {