Auto merge of #84842 - blkerby:null_lowercase, r=joshtriplett

Replace 'NULL' with 'null'

This replaces occurrences of "NULL" with "null" in docs, comments, and compiler error/lint messages. This is for the sake of consistency, as the lowercase "null" is already the dominant form in Rust. The all-caps NULL looks like the C macro (or SQL keyword), which seems out of place in a Rust context, given that NULL does not exist in the Rust language or standard library (instead having [`ptr::null()`](https://doc.rust-lang.org/stable/std/ptr/fn.null.html)).

Author: bors

compiler/rustc_codegen_llvm/src/metadata.rs

@@ -66,7 +66,7 @@ fn search_meta_section<'a>(
             let mut name_buf = None;
             let name_len = llvm::LLVMRustGetSectionName(si.llsi, &mut name_buf);
             let name = name_buf.map_or_else(
-                String::new, // We got a NULL ptr, ignore `name_len`.
+                String::new, // We got a null ptr, ignore `name_len`.
                 |buf| {
                     String::from_utf8(
                         slice::from_raw_parts(buf.as_ptr() as *const u8, name_len as usize)

compiler/rustc_lint/src/builtin.rs

@@ -2328,7 +2328,7 @@ const HAS_MIN_FEATURES: &[Symbol] = &[sym::specialization];
 
 declare_lint! {
     /// The `invalid_value` lint detects creating a value that is not valid,
-    /// such as a NULL reference.
+    /// such as a null reference.
     ///
     /// ### Example
     ///
@@ -2359,7 +2359,7 @@ declare_lint! {
     /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
     pub INVALID_VALUE,
     Warn,
-    "an invalid value is being created (such as a NULL reference)"
+    "an invalid value is being created (such as a null reference)"
 }
 
 declare_lint_pass!(InvalidValue => [INVALID_VALUE]);

compiler/rustc_metadata/src/dynamic_lib.rs

@@ -105,7 +105,7 @@ mod dl {
             return Ok(ret.cast());
         }
 
-        // A NULL return from `dlopen` indicates that an error has definitely occurred, so if
+        // A null return from `dlopen` indicates that an error has definitely occurred, so if
         // nothing is in `dlerror`, we are racing with another thread that has stolen our error
         // message. See the explanation on the `dl::error` module for more information.
         dlerror.get().and_then(|()| Err("Unknown error".to_string()))
@@ -117,7 +117,7 @@ mod dl {
     ) -> Result<*mut u8, String> {
         let mut dlerror = error::lock();
 
-        // Unlike `dlopen`, it's possible for `dlsym` to return NULL without overwriting `dlerror`.
+        // Unlike `dlopen`, it's possible for `dlsym` to return null without overwriting `dlerror`.
         // Because of this, we clear `dlerror` before calling `dlsym` to avoid picking up a stale
         // error message by accident.
         dlerror.clear();
@@ -128,7 +128,7 @@ mod dl {
             return Ok(ret.cast());
         }
 
-        // If `dlsym` returns NULL but there is nothing in `dlerror` it means one of two things:
+        // If `dlsym` returns null but there is nothing in `dlerror` it means one of two things:
         // - We tried to load a symbol mapped to address 0. This is not technically an error but is
         //   unlikely to occur in practice and equally unlikely to be handled correctly by calling
         //   code. Therefore we treat it as an error anyway.

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -185,7 +185,7 @@ impl fmt::Display for CheckInAllocMsg {
             "{}",
             match *self {
                 CheckInAllocMsg::MemoryAccessTest => "memory access",
-                CheckInAllocMsg::NullPointerTest => "NULL pointer test",
+                CheckInAllocMsg::NullPointerTest => "null pointer test",
                 CheckInAllocMsg::PointerArithmeticTest => "pointer arithmetic",
                 CheckInAllocMsg::InboundsTest => "inbounds test",
             }
@@ -309,7 +309,7 @@ impl fmt::Display for UndefinedBehaviorInfo<'_> {
                 allocation_size.bytes()
             ),
             DanglingIntPointer(_, CheckInAllocMsg::NullPointerTest) => {
-                write!(f, "NULL pointer is not allowed for this operation")
+                write!(f, "null pointer is not allowed for this operation")
             }
             DanglingIntPointer(i, msg) => {
                 write!(f, "{} failed: 0x{:x} is not a valid pointer", msg, i)

compiler/rustc_middle/src/mir/query.rs

@@ -81,7 +81,7 @@ impl UnsafetyViolationDetails {
             ),
             DerefOfRawPointer => (
                 "dereference of raw pointer",
-                "raw pointers may be NULL, dangling or unaligned; they can violate aliasing rules \
+                "raw pointers may be null, dangling or unaligned; they can violate aliasing rules \
                  and cause data races: all of these are undefined behavior",
             ),
             AssignToDroppingUnionField => (

compiler/rustc_mir/src/interpret/intrinsics.rs

@@ -348,8 +348,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let b = self.read_immediate(&args[1])?.to_scalar()?;
 
                 // Special case: if both scalars are *equal integers*
-                // and not NULL, we pretend there is an allocation of size 0 right there,
-                // and their offset is 0. (There's never a valid object at NULL, making it an
+                // and not null, we pretend there is an allocation of size 0 right there,
+                // and their offset is 0. (There's never a valid object at null, making it an
                 // exception from the exception.)
                 // This is the dual to the special exception for offset-by-0
                 // in the inbounds pointer offset operation (see the Miri code, `src/operator.rs`).
@@ -501,7 +501,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
     /// Offsets a pointer by some multiple of its type, returning an error if the pointer leaves its
     /// allocation. For integer pointers, we consider each of them their own tiny allocation of size
-    /// 0, so offset-by-0 (and only 0) is okay -- except that NULL cannot be offset by _any_ value.
+    /// 0, so offset-by-0 (and only 0) is okay -- except that null cannot be offset by _any_ value.
     pub fn ptr_offset_inbounds(
         &self,
         ptr: Scalar<M::PointerTag>,
@@ -521,7 +521,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         // pointers to be properly aligned (unlike a read/write operation).
         let min_ptr = if offset_bytes >= 0 { ptr } else { offset_ptr };
         let size = offset_bytes.unsigned_abs();
-        // This call handles checking for integer/NULL pointers.
+        // This call handles checking for integer/null pointers.
         self.memory.check_ptr_access_align(
             min_ptr,
             Size::from_bytes(size),

compiler/rustc_mir/src/interpret/memory.rs

@@ -2,7 +2,7 @@
 //!
 //! Generally, we use `Pointer` to denote memory addresses. However, some operations
 //! have a "size"-like parameter, and they take `Scalar` for the address because
-//! if the size is 0, then the pointer can also be a (properly aligned, non-NULL)
+//! if the size is 0, then the pointer can also be a (properly aligned, non-null)
 //! integer. It is crucial that these operations call `check_align` *before*
 //! short-circuiting the empty case!
 
@@ -105,7 +105,7 @@ pub struct Memory<'mir, 'tcx, M: Machine<'mir, 'tcx>> {
     /// Map for "extra" function pointers.
     extra_fn_ptr_map: FxHashMap<AllocId, M::ExtraFnVal>,
 
-    /// To be able to compare pointers with NULL, and to check alignment for accesses
+    /// To be able to compare pointers with null, and to check alignment for accesses
     /// to ZSTs (where pointers may dangle), we keep track of the size even for allocations
     /// that do not exist any more.
     // FIXME: this should not be public, but interning currently needs access to it
@@ -391,7 +391,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             Ok(bits) => {
                 let bits = u64::try_from(bits).unwrap(); // it's ptr-sized
                 assert!(size.bytes() == 0);
-                // Must be non-NULL.
+                // Must be non-null.
                 if bits == 0 {
                     throw_ub!(DanglingIntPointer(0, msg))
                 }
@@ -404,7 +404,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             Err(ptr) => {
                 let (allocation_size, alloc_align) =
                     self.get_size_and_align(ptr.alloc_id, AllocCheck::Dereferenceable)?;
-                // Test bounds. This also ensures non-NULL.
+                // Test bounds. This also ensures non-null.
                 // It is sufficient to check this for the end pointer. The addition
                 // checks for overflow.
                 let end_ptr = ptr.offset(size, self)?;
@@ -436,7 +436,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         })
     }
 
-    /// Test if the pointer might be NULL.
+    /// Test if the pointer might be null.
     pub fn ptr_may_be_null(&self, ptr: Pointer<M::PointerTag>) -> bool {
         let (size, _align) = self
             .get_size_and_align(ptr.alloc_id, AllocCheck::MaybeDead)

compiler/rustc_mir/src/interpret/place.rs

@@ -375,7 +375,7 @@ where
         assert!(place.mplace.align <= align, "dynamic alignment less strict than static one?");
         // Check (stricter) dynamic alignment, unless forced otherwise.
         place.mplace.align = force_align.unwrap_or(align);
-        // When dereferencing a pointer, it must be non-NULL, aligned, and live.
+        // When dereferencing a pointer, it must be non-null, aligned, and live.
         if let Some(ptr) = self.check_mplace_access(&place, Some(size))? {
             place.mplace.ptr = ptr.into();
         }

compiler/rustc_mir/src/interpret/validity.rs

@@ -427,7 +427,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                     has.bytes()
                 },
             err_ub!(DanglingIntPointer(0, _)) =>
-                { "a NULL {}", kind },
+                { "a null {}", kind },
             err_ub!(DanglingIntPointer(i, _)) =>
                 { "a dangling {} (address 0x{:x} is unallocated)", kind, i },
             err_ub!(PointerOutOfBounds { .. }) =>
@@ -662,10 +662,10 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
         let bits = match value.to_bits_or_ptr(op.layout.size, self.ecx) {
             Err(ptr) => {
                 if lo == 1 && hi == max_hi {
-                    // Only NULL is the niche.  So make sure the ptr is NOT NULL.
+                    // Only null is the niche.  So make sure the ptr is NOT null.
                     if self.ecx.memory.ptr_may_be_null(ptr) {
                         throw_validation_failure!(self.path,
-                            { "a potentially NULL pointer" }
+                            { "a potentially null pointer" }
                             expected {
                                 "something that cannot possibly fail to be {}",
                                 wrapping_range_format(valid_range, max_hi)

library/alloc/src/boxed.rs

@@ -84,7 +84,7 @@
 //! /* Returns ownership to the caller */
 //! struct Foo* foo_new(void);
 //!
-//! /* Takes ownership from the caller; no-op when invoked with NULL */
+//! /* Takes ownership from the caller; no-op when invoked with null */
 //! void foo_delete(struct Foo*);
 //! ```
 //!