From 0ea82de9576a270a99c3bd79ab80d044c3ba9e45 Mon Sep 17 00:00:00 2001
From: Yara <git@yara.blue>
Date: Fri, 7 Aug 2026 16:04:30 +0200
Subject: [PATCH] Add `TypeId::is_signed` method

---
 .../src/const_eval/machine.rs                 |  5 +++++
 .../rustc_hir_analysis/src/check/intrinsic.rs |  2 ++
 compiler/rustc_span/src/symbol.rs             |  1 +
 library/core/src/intrinsics/mod.rs            |  8 +++++++
 library/core/src/mem/type_info.rs             | 21 +++++++++++++++++++
 5 files changed, 37 insertions(+)

diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index 3f52fbecb0950..e27699253dcc0 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -605,6 +605,11 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
                 ecx.write_type_info(ty, dest)?;
             }
 
+            sym::type_id_is_signed => {
+                let ty = ecx.read_type_id(&args[0])?;
+                ecx.write_scalar(Scalar::from_bool(ty.is_signed()), dest)?;
+            }
+
             sym::size_of_type_id => {
                 let ty = ecx.read_type_id(&args[0])?;
                 let layout = ecx.layout_of(ty)?;
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index 67fddd87fbb1d..311a68d83f91f 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -220,6 +220,7 @@ fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -> hi
         | sym::type_id_field_representing_type
         | sym::type_id_fields
         | sym::type_id_generics
+        | sym::type_id_is_signed
         | sym::type_id_variants
         | sym::type_id_vtable
         | sym::type_name
@@ -331,6 +332,7 @@ pub(crate) fn check_intrinsic_type(
             (0, 0, vec![type_id_ty(), tcx.types.usize, tcx.types.usize], type_id_ty())
         }
         sym::type_id_fields => (0, 0, vec![type_id_ty(), tcx.types.usize], tcx.types.usize),
+        sym::type_id_is_signed => (0, 0, vec![type_id_ty()], tcx.types.bool),
         sym::type_id_variants => (0, 0, vec![type_id_ty()], tcx.types.usize),
         sym::type_id_vtable => {
             let dyn_metadata = tcx.require_lang_item(LangItem::DynMetadata, span);
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index a453cc6b555db..84f61bb7e0209 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -2174,6 +2174,7 @@ symbols! {
         type_id_field_representing_type,
         type_id_fields,
         type_id_generics,
+        type_id_is_signed,
         type_id_variants,
         type_id_vtable,
         type_info,
diff --git a/library/core/src/intrinsics/mod.rs b/library/core/src/intrinsics/mod.rs
index fad2cb08a8a64..4e67199bba8c9 100644
--- a/library/core/src/intrinsics/mod.rs
+++ b/library/core/src/intrinsics/mod.rs
@@ -3128,6 +3128,14 @@ pub const fn type_id_eq(a: crate::any::TypeId, b: crate::any::TypeId) -> bool {
     unsafe { crate::mem::transmute::<_, u128>(a) == crate::mem::transmute::<_, u128>(b) }
 }
 
+/// Returns whether the type represented by this `TypeId` is a signed integer.
+///
+/// The more user-friendly version of this intrinsic is [`core::any::TypeId::is_signed`].
+#[rustc_intrinsic]
+#[unstable(feature = "core_intrinsics", issue = "none")]
+#[rustc_comptime]
+pub fn type_id_is_signed(_id: crate::any::TypeId) -> bool;
+
 /// Gets the size of the type represented by this `TypeId`.
 ///
 /// The more user-friendly version of this intrinsic is [`core::any::TypeId::size`].
diff --git a/library/core/src/mem/type_info.rs b/library/core/src/mem/type_info.rs
index 66f85dab7b6c9..dd97a3c7197fd 100644
--- a/library/core/src/mem/type_info.rs
+++ b/library/core/src/mem/type_info.rs
@@ -379,6 +379,27 @@ pub enum Abi {
 }
 
 impl TypeId {
+    /// Returns `true` if the type represented by this `TypeId` is an signed integer.
+    ///
+    /// For everything else this returns false.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(type_info)]
+    /// use std::any::TypeId;
+    ///
+    /// assert_eq!(const { TypeId::of::<i32>().is_signed() }, true);
+    /// assert_eq!(const { TypeId::of::<u8>().is_signed() }, false);
+    /// assert_eq!(const { TypeId::of::<bool>().is_signed() }, false);
+    /// ```
+    #[unstable(feature = "type_info", issue = "146922")]
+    #[rustc_const_unstable(feature = "type_info", issue = "146922")]
+    #[rustc_comptime]
+    pub fn is_signed(self) -> bool {
+        intrinsics::type_id_is_signed(self)
+    }
+
     /// Returns the size of the type represented by this `TypeId`. `None` if it is unsized.
     ///
     /// # Examples