Convert to inline diagnostics in rustc_const_eval

[GuillaumeGomez]

Part of #151366.

r? @JonathanBrouwer

[rustbot]

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

Some changes occurred to constck

cc @fee1-dead

⚠️ #[rustc_intrinsic_const_stable_indirect] controls whether intrinsics can be exposed to stable const
code; adding it needs t-lang approval.

cc @rust-lang/wg-const-eval

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

[RalfJung]

Here and in many other places, the indentation is rather broken, making this quite hard to read. Is there a way to avoid that?

[JonathanBrouwer]

On my PRs I manually indented all of these to align with the surrounding code, is very possible to fix :)

[RalfJung]

Something seems to have gone wrong here...

[JonathanBrouwer]

Why did this diagnostic change?

[rust-log-analyzer]

The job aarch64-gnu-llvm-20-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

fmt check
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:21:
 use crate::interpret::InternKind;
 
 #[derive(Diagnostic)]
-#[diag(r#"encountered dangling pointer in final value of {$kind ->
+#[diag(
+    r#"encountered dangling pointer in final value of {$kind ->
     [static] static
     [static_mut] mutable static
     [const] constant
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:28:
     [promoted] promoted
     *[other] {""}
-}"#)]
+}"#
+)]
 pub(crate) struct DanglingPtrInFinal {
     #[primary_span]
     pub span: Span,
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:44:
 }
 
 #[derive(Diagnostic)]
-#[diag(r#"encountered mutable pointer in final value of {$kind ->
+#[diag(
+    r#"encountered mutable pointer in final value of {$kind ->
     [static] static
     [static_mut] mutable static
     [const] constant
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:51:
     [promoted] promoted
     *[other] {""}
-}"#)]
+}"#
+)]
 pub(crate) struct MutablePtrInFinal {
     #[primary_span]
     pub span: Span,
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:68:
 }
 
 #[derive(Diagnostic)]
-#[diag(r#"encountered partial pointer in final value of {$kind ->
+#[diag(
+    r#"encountered partial pointer in final value of {$kind ->
     [static] static
     [static_mut] mutable static
     [const] constant
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:75:
     [promoted] promoted
     *[other] {""}
-}"#)]
+}"#
+)]
 #[note(
     "while pointers can be broken apart into individual bytes during const-evaluation, only complete pointers (with all their bytes in the right order) are supported in the final value"
 )]
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:119:
 #[derive(Diagnostic)]
 #[diag("pointers cannot be cast to integers during const eval")]
 #[note("at compile-time, pointers do not have an integer value")]
-#[note("avoiding this restriction via `transmute`, `union`, or raw pointers leads to compile-time undefined behavior")]
+#[note(
+    "avoiding this restriction via `transmute`, `union`, or raw pointers leads to compile-time undefined behavior"
+)]
 pub(crate) struct RawPtrToIntErr {
     #[primary_span]
     pub span: Span,
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:213:
 #[note(
     "temporaries in constants and statics can have their lifetime extended until the end of the program"
 )]
-#[note(
-    "to avoid accidentally creating global mutable state, such temporaries must be immutable"
-)]
+#[note("to avoid accidentally creating global mutable state, such temporaries must be immutable")]
 #[help(
     "if you really want global mutable state, try replacing the temporary by an interior mutable `static` or a `static mut`"
 )]
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:292:
 }s"#, code = E0010)]
 pub(crate) struct UnallowedHeapAllocations {
     #[primary_span]
-    #[label(r#"allocation not allowed in {$kind ->
+    #[label(
+        r#"allocation not allowed in {$kind ->
     [const] constant
     [static] static
     [const_fn] constant function
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:299:
     *[other] {""}
-}s"#)]
+}s"#
+    )]
     pub span: Span,
     pub kind: ConstContext,
     #[note(
Diff in /checkout/compiler/rustc_const_eval/src/errors.rs:324:
 #[note(
     "temporaries in constants and statics can have their lifetime extended until the end of the program"
 )]
-#[note(
-    "to avoid accidentally creating global mutable state, such temporaries must be immutable"
+#[note("to avoid accidentally creating global mutable state, such temporaries must be immutable")]
+#[help(
+    "if you really want global mutable state, try replacing the temporary by an interior mutable `static` or a `static mut`"
 )]
-#[help("if you really want global mutable state, try replacing the temporary by an interior mutable `static` or a `static mut`")]
 pub(crate) struct InteriorMutableBorrowEscaping {
     #[primary_span]
     #[label("this borrow of an interior mutable value refers to such a temporary")]
fmt: checked 6701 files
Bootstrap failed while executing `--stage 2 test --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Build completed unsuccessfully in 0:00:26
  local time: Thu Feb  5 21:33:13 UTC 2026
  network time: Thu, 05 Feb 2026 21:33:14 GMT

[JonathanBrouwer]

@rustbot author

[rust-bors]

☔ The latest upstream changes (presumably #152213) made this pull request unmergeable. Please resolve the merge conflicts.