---

yaml
---
r: 236015
b: refs/heads/stable
c: 3318e3d
h: refs/heads/master
i:
  236013: a08e8c1
  236011: d46f065
  236007: 5697123
  235999: 6e8cc28
v: v3

Author: Gankra

[refs]

@@ -29,7 +29,7 @@ refs/heads/tmp: afae2ff723393b3ab4ccffef6ac7c6d1809e2da0
 refs/tags/1.0.0-alpha.2: 4c705f6bc559886632d3871b04f58aab093bfa2f
 refs/tags/homu-tmp: f859507de8c410b648d934d8f5ec1c52daac971d
 refs/tags/1.0.0-beta: 8cbb92b53468ee2b0c2d3eeb8567005953d40828
-refs/heads/stable: 39c047317f39df2b0f55da10f276b88826f54d3b
+refs/heads/stable: 3318e3d8edd4336021f4314a25618e77061f2684
 refs/tags/1.0.0: 55bd4f8ff2b323f317ae89e254ce87162d52a375
 refs/tags/1.1.0: bc3c16f09287e5545c1d3f76b7abd54f2eca868b
 refs/tags/1.2.0: f557861f822c34f07270347b94b5280de20a597e

branches/stable/conversions.md

@@ -54,15 +54,27 @@ actually think about it is probably the general *Deref Coercion*: `&T` coerces t
 
 Casts are a superset of coercions: every coercion can be explicitly invoked via a cast,
 but some changes require a cast. These "true casts" are generally regarded as dangerous or
-problematic actions. The set of true casts is actually quite small, and once again revolves
-largely around pointers. However it also introduces the primary mechanism to convert between
-numeric types.
+problematic actions. True casts revolves around raw pointers and the primitive numeric
+types. Here's an exhaustive list of all the true casts:
 
 * rawptr -> rawptr (e.g. `*mut T as *const T` or `*mut T as *mut U`)
 * rawptr <-> usize (e.g. `*mut T as usize` or `usize as *mut T`)
-* primitive -> primitive (e.g. `u32 as u8` or `u8 as u32`)
-* c-like enum -> integer/bool (e.g. `DaysOfWeek as u8`)
+* number -> number (e.g. `u32 as i8` or `i16 as f64`)
+* c-like enum -> integer/bool (e.g. `DaysOfWeek as u32`)
 * `u8` -> `char`
+* something about arrays?
+
+For number -> number casts, there are quite a few cases to consider:
+
+* unsigned to bigger unsigned will zero-extend losslessly
+* unsigned to smaller unsigned will truncate via wrapping
+* signed to unsigned will  ... TODO rest of this list
+
+The casts involving rawptrs also allow us to completely bypass type-safety
+by re-interpretting a pointer of T to a pointer of U for arbitrary types, as
+well as interpret integers as addresses. However it is impossible to actually
+*capitalize* on this violation in Safe Rust, because derefencing a raw ptr is
+`unsafe`.
 
 
 ## Conversion Traits