From 89625360ec4fa11bdc073a74607c7ff0f624fb96 Mon Sep 17 00:00:00 2001
From: xizheyin <xizheyin@smail.nju.edu.cn>
Date: Wed, 26 Mar 2025 11:27:52 +0800
Subject: [PATCH 1/2] Add ui test cast-array-issue-138836
Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>
---
tests/ui/cast/cast-array-issue-138836.rs | 5 +++++
tests/ui/cast/cast-array-issue-138836.stderr | 12 ++++++++++++
2 files changed, 17 insertions(+)
create mode 100644 tests/ui/cast/cast-array-issue-138836.rs
create mode 100644 tests/ui/cast/cast-array-issue-138836.stderr
diff --git a/tests/ui/cast/cast-array-issue-138836.rs b/tests/ui/cast/cast-array-issue-138836.rs
new file mode 100644
index 0000000000000..6fd65d5878ac9
--- /dev/null
+++ b/tests/ui/cast/cast-array-issue-138836.rs
@@ -0,0 +1,5 @@
+fn main() {
+ let a: [u8; 3] = [1,2,3];
+ let b = &a;
+ let c = b as *const [u32; 3]; //~ ERROR mismatched types [E0308]
+}
diff --git a/tests/ui/cast/cast-array-issue-138836.stderr b/tests/ui/cast/cast-array-issue-138836.stderr
new file mode 100644
index 0000000000000..fe20d429a4989
--- /dev/null
+++ b/tests/ui/cast/cast-array-issue-138836.stderr
@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+ --> $DIR/cast-array-issue-138836.rs:4:13
+ |
+LL | let c = b as *const [u32; 3];
+ | ^^^^^^^^^^^^^^^^^^^^ expected `[u8; 3]`, found `[u32; 3]`
+ |
+ = note: expected array `[u8; 3]`
+ found array `[u32; 3]`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.
From a34c42fefabc774af2d8b2c5a5a100c0697d2ba9 Mon Sep 17 00:00:00 2001
From: xizheyin <xizheyin@smail.nju.edu.cn>
Date: Wed, 26 Mar 2025 11:31:58 +0800
Subject: [PATCH 2/2] Expect an array when expected and acutal types are both
arrays during cast
Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>
---
compiler/rustc_hir_typeck/src/cast.rs | 39 ++++++++++----------
tests/ui/cast/cast-array-issue-138836.rs | 2 +-
tests/ui/cast/cast-array-issue-138836.stderr | 9 ++---
tests/ui/consts/const-cast-wrong-type.rs | 2 +-
tests/ui/consts/const-cast-wrong-type.stderr | 6 +--
5 files changed, 28 insertions(+), 30 deletions(-)
diff --git a/compiler/rustc_hir_typeck/src/cast.rs b/compiler/rustc_hir_typeck/src/cast.rs
index 8f5fddd19d7f6..b19d9efe2c6f5 100644
--- a/compiler/rustc_hir_typeck/src/cast.rs
+++ b/compiler/rustc_hir_typeck/src/cast.rs
@@ -1042,30 +1042,31 @@ impl<'a, 'tcx> CastCheck<'tcx> {
m_cast: ty::TypeAndMut<'tcx>,
) -> Result<CastKind, CastError<'tcx>> {
// array-ptr-cast: allow mut-to-mut, mut-to-const, const-to-const
- if m_expr.mutbl >= m_cast.mutbl {
- if let ty::Array(ety, _) = m_expr.ty.kind() {
- // Due to the limitations of LLVM global constants,
- // region pointers end up pointing at copies of
- // vector elements instead of the original values.
- // To allow raw pointers to work correctly, we
- // need to special-case obtaining a raw pointer
- // from a region pointer to a vector.
-
- // Coerce to a raw pointer so that we generate RawPtr in MIR.
- let array_ptr_type = Ty::new_ptr(fcx.tcx, m_expr.ty, m_expr.mutbl);
- fcx.coerce(self.expr, self.expr_ty, array_ptr_type, AllowTwoPhase::No, None)
- .unwrap_or_else(|_| {
- bug!(
+ if m_expr.mutbl >= m_cast.mutbl
+ && let ty::Array(ety, _) = m_expr.ty.kind()
+ && fcx.can_eq(fcx.param_env, *ety, m_cast.ty)
+ {
+ // Due to the limitations of LLVM global constants,
+ // region pointers end up pointing at copies of
+ // vector elements instead of the original values.
+ // To allow raw pointers to work correctly, we
+ // need to special-case obtaining a raw pointer
+ // from a region pointer to a vector.
+
+ // Coerce to a raw pointer so that we generate RawPtr in MIR.
+ let array_ptr_type = Ty::new_ptr(fcx.tcx, m_expr.ty, m_expr.mutbl);
+ fcx.coerce(self.expr, self.expr_ty, array_ptr_type, AllowTwoPhase::No, None)
+ .unwrap_or_else(|_| {
+ bug!(
"could not cast from reference to array to pointer to array ({:?} to {:?})",
self.expr_ty,
array_ptr_type,
)
- });
+ });
- // this will report a type mismatch if needed
- fcx.demand_eqtype(self.span, *ety, m_cast.ty);
- return Ok(CastKind::ArrayPtrCast);
- }
+ // this will report a type mismatch if needed
+ fcx.demand_eqtype(self.span, *ety, m_cast.ty);
+ return Ok(CastKind::ArrayPtrCast);
}
Err(CastError::IllegalCast)
diff --git a/tests/ui/cast/cast-array-issue-138836.rs b/tests/ui/cast/cast-array-issue-138836.rs
index 6fd65d5878ac9..3f8098e76fd29 100644
--- a/tests/ui/cast/cast-array-issue-138836.rs
+++ b/tests/ui/cast/cast-array-issue-138836.rs
@@ -1,5 +1,5 @@
fn main() {
let a: [u8; 3] = [1,2,3];
let b = &a;
- let c = b as *const [u32; 3]; //~ ERROR mismatched types [E0308]
+ let c = b as *const [u32; 3]; //~ ERROR casting `&[u8; 3]` as `*const [u32; 3]` is invalid
}
diff --git a/tests/ui/cast/cast-array-issue-138836.stderr b/tests/ui/cast/cast-array-issue-138836.stderr
index fe20d429a4989..309474c29f933 100644
--- a/tests/ui/cast/cast-array-issue-138836.stderr
+++ b/tests/ui/cast/cast-array-issue-138836.stderr
@@ -1,12 +1,9 @@
-error[E0308]: mismatched types
+error[E0606]: casting `&[u8; 3]` as `*const [u32; 3]` is invalid
--> $DIR/cast-array-issue-138836.rs:4:13
|
LL | let c = b as *const [u32; 3];
- | ^^^^^^^^^^^^^^^^^^^^ expected `[u8; 3]`, found `[u32; 3]`
- |
- = note: expected array `[u8; 3]`
- found array `[u32; 3]`
+ | ^^^^^^^^^^^^^^^^^^^^
error: aborting due to 1 previous error
-For more information about this error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0606`.
diff --git a/tests/ui/consts/const-cast-wrong-type.rs b/tests/ui/consts/const-cast-wrong-type.rs
index 6e055a2bcd340..9936a660936b0 100644
--- a/tests/ui/consts/const-cast-wrong-type.rs
+++ b/tests/ui/consts/const-cast-wrong-type.rs
@@ -1,5 +1,5 @@
const a: [u8; 3] = ['h' as u8, 'i' as u8, 0 as u8];
-const b: *const i8 = &a as *const i8; //~ ERROR mismatched types
+const b: *const i8 = &a as *const i8; //~ ERROR casting `&[u8; 3]` as `*const i8` is invalid
fn main() {
}
diff --git a/tests/ui/consts/const-cast-wrong-type.stderr b/tests/ui/consts/const-cast-wrong-type.stderr
index 44361f15d8a98..0730bac22354d 100644
--- a/tests/ui/consts/const-cast-wrong-type.stderr
+++ b/tests/ui/consts/const-cast-wrong-type.stderr
@@ -1,9 +1,9 @@
-error[E0308]: mismatched types
+error[E0606]: casting `&[u8; 3]` as `*const i8` is invalid
--> $DIR/const-cast-wrong-type.rs:2:22
|
LL | const b: *const i8 = &a as *const i8;
- | ^^^^^^^^^^^^^^^ expected `u8`, found `i8`
+ | ^^^^^^^^^^^^^^^
error: aborting due to 1 previous error
-For more information about this error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0606`.