Add description for every module in check_consts

Author: ecstatic-morse

src/librustc_mir/transform/check_consts/mod.rs

@@ -1,3 +1,9 @@
+//! Check the bodies of `const`s, `static`s and `const fn`s for illegal operations.
+//!
+//! This module will eventually replace the parts of `qualify_consts.rs` that check whether a local
+//! has interior mutability or needs to be dropped, as well as the visitor that emits errors when
+//! it finds operations that are invalid in a certain context.
+
 use rustc::hir::def_id::DefId;
 use rustc::mir;
 use rustc::ty::{self, TyCtxt};

src/librustc_mir/transform/check_consts/ops.rs

@@ -1,3 +1,5 @@
+//! Concrete error types for all operations which may be invalid in a certain const context.
+
 use rustc::hir::def_id::DefId;
 use rustc::mir::BorrowKind;
 use rustc::session::config::nightly_options;

src/librustc_mir/transform/check_consts/qualifs.rs

@@ -1,3 +1,5 @@
+//! A copy of the `Qualif` trait in `qualify_consts.rs` that is suitable for the new validator.
+
 use rustc::mir::*;
 use rustc::mir::interpret::ConstValue;
 use rustc::ty::{self, Ty};

src/librustc_mir/transform/check_consts/resolver.rs

@@ -1,3 +1,8 @@
+//! Propagate `Qualif`s between locals and query the results.
+//!
+//! This also contains the dataflow analysis used to track `Qualif`s on complex control-flow
+//! graphs.
+
 use rustc::mir::visit::Visitor;
 use rustc::mir::{self, BasicBlock, Local, Location};
 use rustc_data_structures::bit_set::BitSet;

src/librustc_mir/transform/check_consts/validation.rs

@@ -1,3 +1,5 @@
+//! The `Visitor` responsible for actually checking a `mir::Body` for invalid operations.
+
 use rustc::hir::{self, def_id::DefId};
 use rustc::mir::visit::{PlaceContext, Visitor, MutatingUseContext, NonMutatingUseContext};
 use rustc::mir::*;