Auto merge of #99203 - GuillaumeGomez:rollup-b2re0dv, r=GuillaumeGomez

Rollup of 10 pull requests

Successful merges:

 - #98789 (rustdoc-json-types: Clean up derives.)
 - #98848 (Build the Clippy book as part of x.py doc)
 - #99020 (check non_exhaustive attr and private fields for transparent types)
 - #99132 (Add some autolabels for A-bootstrap and T-infra)
 - #99148 (Clarify that [iu]size bounds were only defined for the target arch)
 - #99152 (Use CSS variables to handle theming (part 2))
 - #99168 (Add regression test for #74713)
 - #99176 (:arrow_up: rust-analyzer)
 - #99183 (Mention rust-analyzer maintainers when `proc_macro` bridge is changed)
 - #99185 (llvm-wrapper: adapt for LLVM API change)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

3 files changed, 127 insertions, 5 deletions

diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 9fc2249b290..6d2cb63c1d7 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -3132,6 +3132,60 @@ declare_lint! {
     "detects unexpected names and values in `#[cfg]` conditions",
 }
 
+declare_lint! {
+    /// The `repr_transparent_external_private_fields` lint
+    /// detects types marked `#[repr(transparent)]` that (transitively)
+    /// contain an external ZST type marked `#[non_exhaustive]` or containing
+    /// private fields
+    ///
+    /// ### Example
+    ///
+    /// ```rust,ignore (needs external crate)
+    /// #![deny(repr_transparent_external_private_fields)]
+    /// use foo::NonExhaustiveZst;
+    ///
+    /// #[repr(transparent)]
+    /// struct Bar(u32, ([u32; 0], NonExhaustiveZst));
+    /// ```
+    ///
+    /// This will produce:
+    ///
+    /// ```text
+    /// error: zero-sized fields in repr(transparent) cannot contain external non-exhaustive types
+    ///  --> src/main.rs:5:28
+    ///   |
+    /// 5 | struct Bar(u32, ([u32; 0], NonExhaustiveZst));
+    ///   |                            ^^^^^^^^^^^^^^^^
+    ///   |
+    /// note: the lint level is defined here
+    ///  --> src/main.rs:1:9
+    ///   |
+    /// 1 | #![deny(repr_transparent_external_private_fields)]
+    ///   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+    ///   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    ///   = note: for more information, see issue #78586 <https://github.com/rust-lang/rust/issues/78586>
+    ///   = note: this struct contains `NonExhaustiveZst`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+    /// ```
+    ///
+    /// ### Explanation
+    ///
+    /// Previous, Rust accepted fields that contain external private zero-sized types,
+    /// even though it should not be a breaking change to add a non-zero-sized field to
+    /// that private type.
+    ///
+    /// This is a [future-incompatible] lint to transition this
+    /// to a hard error in the future. See [issue #78586] for more details.
+    ///
+    /// [issue #78586]: https://github.com/rust-lang/rust/issues/78586
+    /// [future-incompatible]: ../index.md#future-incompatible-lints
+    pub REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
+    Warn,
+    "tranparent type contains an external ZST that is marked #[non_exhaustive] or contains private fields",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #78586 <https://github.com/rust-lang/rust/issues/78586>",
+    };
+}
+
 declare_lint_pass! {
     /// Does nothing as a lint pass, but registers some `Lint`s
     /// that are used by other parts of the compiler.
@@ -3237,6 +3291,7 @@ declare_lint_pass! {
         DEPRECATED_WHERE_CLAUSE_LOCATION,
         TEST_UNSTABLE_LINT,
         FFI_UNWIND_CALLS,
+        REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
     ]
 }
 
diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index 8c5b4e2dc96..7ac3157e7a1 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -411,8 +411,14 @@ LLVMRustInlineAsm(LLVMTypeRef Ty, char *AsmString, size_t AsmStringLen,
 
 extern "C" bool LLVMRustInlineAsmVerify(LLVMTypeRef Ty, char *Constraints,
                                         size_t ConstraintsLen) {
+#if LLVM_VERSION_LT(15, 0)
   return InlineAsm::Verify(unwrap<FunctionType>(Ty),
                            StringRef(Constraints, ConstraintsLen));
+#else
+  // llvm::Error converts to true if it is an error.
+  return !llvm::errorToBool(InlineAsm::verify(
+      unwrap<FunctionType>(Ty), StringRef(Constraints, ConstraintsLen)));
+#endif
 }
 
 extern "C" void LLVMRustAppendModuleInlineAsm(LLVMModuleRef M, const char *Asm,
diff --git a/compiler/rustc_typeck/src/check/check.rs b/compiler/rustc_typeck/src/check/check.rs
index e9709b64d93..79edbeab9c7 100644
--- a/compiler/rustc_typeck/src/check/check.rs
+++ b/compiler/rustc_typeck/src/check/check.rs
@@ -17,6 +17,7 @@ use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::{RegionVariableOrigin, TyCtxtInferExt};
 use rustc_infer::traits::Obligation;
+use rustc_lint::builtin::REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::layout::{LayoutError, MAX_SIMD_LANES};
 use rustc_middle::ty::subst::GenericArgKind;
@@ -1318,7 +1319,8 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, adt: ty::AdtD
         }
     }
 
-    // For each field, figure out if it's known to be a ZST and align(1)
+    // For each field, figure out if it's known to be a ZST and align(1), with "known"
+    // respecting #[non_exhaustive] attributes.
     let field_infos = adt.all_fields().map(|field| {
         let ty = field.ty(tcx, InternalSubsts::identity_for_item(tcx, field.did));
         let param_env = tcx.param_env(field.did);
@@ -1327,16 +1329,56 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, adt: ty::AdtD
         let span = tcx.hir().span_if_local(field.did).unwrap();
         let zst = layout.map_or(false, |layout| layout.is_zst());
         let align1 = layout.map_or(false, |layout| layout.align.abi.bytes() == 1);
-        (span, zst, align1)
+        if !zst {
+            return (span, zst, align1, None);
+        }
+
+        fn check_non_exhaustive<'tcx>(
+            tcx: TyCtxt<'tcx>,
+            t: Ty<'tcx>,
+        ) -> ControlFlow<(&'static str, DefId, SubstsRef<'tcx>, bool)> {
+            match t.kind() {
+                ty::Tuple(list) => list.iter().try_for_each(|t| check_non_exhaustive(tcx, t)),
+                ty::Array(ty, _) => check_non_exhaustive(tcx, *ty),
+                ty::Adt(def, subst) => {
+                    if !def.did().is_local() {
+                        let non_exhaustive = def.is_variant_list_non_exhaustive()
+                            || def
+                                .variants()
+                                .iter()
+                                .any(ty::VariantDef::is_field_list_non_exhaustive);
+                        let has_priv = def.all_fields().any(|f| !f.vis.is_public());
+                        if non_exhaustive || has_priv {
+                            return ControlFlow::Break((
+                                def.descr(),
+                                def.did(),
+                                subst,
+                                non_exhaustive,
+                            ));
+                        }
+                    }
+                    def.all_fields()
+                        .map(|field| field.ty(tcx, subst))
+                        .try_for_each(|t| check_non_exhaustive(tcx, t))
+                }
+                _ => ControlFlow::Continue(()),
+            }
+        }
+
+        (span, zst, align1, check_non_exhaustive(tcx, ty).break_value())
     });
 
-    let non_zst_fields =
-        field_infos.clone().filter_map(|(span, zst, _align1)| if !zst { Some(span) } else { None });
+    let non_zst_fields = field_infos
+        .clone()
+        .filter_map(|(span, zst, _align1, _non_exhaustive)| if !zst { Some(span) } else { None });
     let non_zst_count = non_zst_fields.clone().count();
     if non_zst_count >= 2 {
         bad_non_zero_sized_fields(tcx, adt, non_zst_count, non_zst_fields, sp);
     }
-    for (span, zst, align1) in field_infos {
+    let incompatible_zst_fields =
+        field_infos.clone().filter(|(_, _, _, opt)| opt.is_some()).count();
+    let incompat = incompatible_zst_fields + non_zst_count >= 2 && non_zst_count < 2;
+    for (span, zst, align1, non_exhaustive) in field_infos {
         if zst && !align1 {
             struct_span_err!(
                 tcx.sess,
@@ -1348,6 +1390,25 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, adt: ty::AdtD
             .span_label(span, "has alignment larger than 1")
             .emit();
         }
+        if incompat && let Some((descr, def_id, substs, non_exhaustive)) = non_exhaustive {
+            tcx.struct_span_lint_hir(
+                REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
+                tcx.hir().local_def_id_to_hir_id(adt.did().expect_local()),
+                span,
+                |lint| {
+                    let note = if non_exhaustive {
+                        "is marked with `#[non_exhaustive]`"
+                    } else {
+                        "contains private fields"
+                    };
+                    let field_ty = tcx.def_path_str_with_substs(def_id, substs);
+                    lint.build("zero-sized fields in repr(transparent) cannot contain external non-exhaustive types")
+                        .note(format!("this {descr} contains `{field_ty}`, which {note}, \
+                            and makes it not a breaking change to become non-zero-sized in the future."))
+                        .emit();
+                },
+            )
+        }
     }
 }