Values and Sized types are not larger than isize::MAX

src/type-layout.md

@@ -18,10 +18,10 @@ r[layout.properties.align]
 The *alignment* of a value specifies what addresses are valid to store the value at. A value of alignment `n` must only be stored at an address that is a multiple of n. For example, a value with an alignment of 2 must be stored at an even address, while a value with an alignment of 1 can be stored at any address. Alignment is measured in bytes, and must be at least 1, and always a power of 2. The alignment of a value can be checked with the [`align_of_val`] function.
 
 r[layout.properties.size]
-The *size* of a value is the offset in bytes between successive elements in an array with that item type including alignment padding. The size of a value is always a multiple of its alignment. Note that some types are zero-sized; 0 is considered a multiple of any alignment (for example, on some platforms, the type `[u16; 0]` has size 0 and alignment 2). The size of a value can be checked with the [`size_of_val`] function.
+The *size* of a value is the offset in bytes between successive elements in an array with that item type including alignment padding. The size of a value is always a multiple of its alignment, and never exceeds `isize::MAX`. Note that some types are zero-sized; 0 is considered a multiple of any alignment (for example, on some platforms, the type `[u16; 0]` has size 0 and alignment 2). The size of a value can be checked with the [`size_of_val`] function.
 
 r[layout.properties.sized]
-Types where all values have the same size and alignment, and both are known at compile time, implement the [`Sized`] trait and can be checked with the [`size_of`] and [`align_of`] functions. Types that are not [`Sized`] are known as [dynamically sized types]. Since all values of a `Sized` type share the same size and alignment, we refer to those shared values as the size of the type and the alignment of the type respectively.
+Types where all values have the same size and alignment, and both are known at compile time, implement the [`Sized`] trait and can be checked with the [`size_of`] and [`align_of`] functions. Types that are not [`Sized`] are known as [dynamically sized types]. Since all values of a `Sized` type share the same size and alignment, we refer to those shared values as the size of the type and the alignment of the type respectively. The size of a `Sized` type is guaranteed not to exceed `isize::MAX`. (Note that this guarantee is distinct from the guarantee that the size of a *value* does not exceed `isize::MAX` -- this guarantee applies *even if a `Sized` type is never instantiated*.)
 
 r[layout.primitive]
 ## Primitive data layout