Add allocation information to undefined behaviour errors.

Author: hameerabbasi

compiler/rustc_mir/src/const_eval/eval_queries.rs

@@ -5,6 +5,7 @@ use crate::interpret::{
     Immediate, InternKind, InterpCx, InterpResult, MPlaceTy, MemoryKind, OpTy, RefTracking, Scalar,
     ScalarMaybeUninit, StackPopCleanup,
 };
+use crate::util::pretty::display_allocation;
 
 use rustc_errors::ErrorReported;
 use rustc_hir::def::DefKind;
@@ -360,6 +361,15 @@ pub fn eval_to_allocation_raw_provider<'tcx>(
                     "it is undefined behavior to use this value",
                     |mut diag| {
                         diag.note(note_on_undefined_behavior_error());
+                        diag.note(&format!(
+                            "the raw bytes of the constant ({}",
+                            display_allocation(
+                                *ecx.tcx,
+                                ecx.tcx
+                                    .global_alloc(mplace.ptr.assert_ptr().alloc_id)
+                                    .unwrap_memory()
+                            )
+                        ));
                         diag.emit();
                     },
                 ))

src/test/ui/const-generics/min_const_generics/invalid-patterns.stderr

@@ -29,6 +29,9 @@ LL |   get_flag::<false, { unsafe { char_raw.character } }>();
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered uninitialized bytes, but expected a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 4, align: 4) {
+               __ __ __ __                                     │ ░░░░
+           }
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/invalid-patterns.rs:39:14
@@ -37,6 +40,9 @@ LL |   get_flag::<{ unsafe { bool_raw.boolean } }, 'z'>();
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 0x42, but expected a boolean
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 1, align: 1) {
+               42                                              │ B
+           }
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/invalid-patterns.rs:41:14
@@ -45,6 +51,9 @@ LL |   get_flag::<{ unsafe { bool_raw.boolean } }, { unsafe { char_raw.character
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 0x42, but expected a boolean
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 1, align: 1) {
+               42                                              │ B
+           }
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/invalid-patterns.rs:41:47
@@ -53,6 +62,9 @@ LL |   get_flag::<{ unsafe { bool_raw.boolean } }, { unsafe { char_raw.character
    |                                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered uninitialized bytes, but expected a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 4, align: 4) {
+               __ __ __ __                                     │ ░░░░
+           }
 
 error: aborting due to 8 previous errors
 

src/test/ui/consts/const-err4.stderr

@@ -5,6 +5,9 @@ LL |     Boo = [unsafe { Foo { b: () }.a }; 4][3],
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered uninitialized bytes, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               __ __ __ __ __ __ __ __                         │ ░░░░░░░░
+           }
 
 error: aborting due to previous error
 

src/test/ui/consts/const-eval/const-pointer-values-in-various-types.stderr

@@ -5,6 +5,9 @@ LL |     const I32_REF_USIZE_UNION: usize = unsafe { Nonsense { int_32_ref: &3 }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered pointer to alloc2, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               ╾───────alloc2────────╼                         │ ╾──────╼
+           }
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:28:43
@@ -47,6 +50,9 @@ LL |     const I32_REF_U64_UNION: u64 = unsafe { Nonsense { int_32_ref: &3 }.uin
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered pointer to alloc18, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               ╾───────alloc18───────╼                         │ ╾──────╼
+           }
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/const-pointer-values-in-various-types.rs:43:5
@@ -55,6 +61,9 @@ LL |     const I32_REF_U128_UNION: u128 = unsafe { Nonsense { int_32_ref: &3 }.u
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered uninitialized bytes, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 16, align: 8) {
+               __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+           }
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:46:43
@@ -96,6 +105,9 @@ LL |     const I32_REF_I64_UNION: i64 = unsafe { Nonsense { int_32_ref: &3 }.int
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered pointer to alloc38, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               ╾───────alloc38───────╼                         │ ╾──────╼
+           }
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/const-pointer-values-in-various-types.rs:61:5
@@ -104,6 +116,9 @@ LL |     const I32_REF_I128_UNION: i128 = unsafe { Nonsense { int_32_ref: &3 }.i
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered uninitialized bytes, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 16, align: 8) {
+               __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+           }
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:64:45
@@ -123,6 +138,9 @@ LL |     const I32_REF_F64_UNION: f64 = unsafe { Nonsense { int_32_ref: &3 }.flo
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered pointer to alloc50, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               ╾───────alloc50───────╼                         │ ╾──────╼
+           }
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:71:47
@@ -186,6 +204,9 @@ LL |     const STR_U64_UNION: u64 = unsafe { Nonsense { stringy: "3" }.uint_64 }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered pointer to alloc71, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               ╾───────alloc71───────╼                         │ ╾──────╼
+           }
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:94:43
@@ -238,6 +259,9 @@ LL |     const STR_I64_UNION: i64 = unsafe { Nonsense { stringy: "3" }.int_64 };
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered pointer to alloc86, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               ╾───────alloc86───────╼                         │ ╾──────╼
+           }
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:113:43
@@ -268,6 +292,9 @@ LL |     const STR_F64_UNION: f64 = unsafe { Nonsense { stringy: "3" }.float_64
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered pointer to alloc95, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               ╾───────alloc95───────╼                         │ ╾──────╼
+           }
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:124:43

src/test/ui/consts/const-eval/heap/alloc_intrinsic_uninit.stderr

@@ -5,6 +5,9 @@ LL | const BAR: &i32 = unsafe { &*(intrinsics::const_allocate(4, 4) as *mut i32)
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered uninitialized bytes at .<deref>, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               ╾───────alloc1────────╼                         │ ╾──────╼
+           }
 
 error: aborting due to previous error
 

src/test/ui/consts/const-eval/ref_to_int_match.stderr

@@ -5,6 +5,9 @@ LL | const BAR: Int = unsafe { Foo { r: &42 }.f };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered pointer to alloc2, but expected initialized plain (non-pointer) bytes
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 8, align: 8) {
+               ╾───────alloc2────────╼                         │ ╾──────╼
+           }
 
 error: could not evaluate constant pattern
   --> $DIR/ref_to_int_match.rs:7:14

src/test/ui/consts/const-eval/transmute-const.stderr

@@ -5,6 +5,9 @@ LL | static FOO: bool = unsafe { mem::transmute(3u8) };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 0x03, but expected a boolean
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+   = note: the raw bytes of the constant (size: 1, align: 1) {
+               03                                              │ .
+           }
 
 error: aborting due to previous error