Clean up testing-only cargo features

This commit ensures that all of the cargo features we have that only exist for
CI/testing purposes, and aren't for external consumption, have a "testing_only_"
prefix.

Author: fitzgen

CONTRIBUTING.md

@@ -65,12 +65,12 @@ $ export LD_LIBRARY_PATH=path/to/clang-3.9/lib # for Linux
 $ export DYLD_LIBRARY_PATH=path/to/clang-3.9/lib # for macOS
 ```
 
-Additionally, you may want to build and test with the `docs_` feature to ensure
-that you aren't forgetting to document types and functions. CI will catch it if
-you forget, but the turn around will be a lot slower ;)
+Additionally, you may want to build and test with the `testing_only_docs`
+feature to ensure that you aren't forgetting to document types and functions. CI
+will catch it if you forget, but the turn around will be a lot slower ;)
 
 ```
-$ cargo build --features docs_
+$ cargo build --features testing_only_docs
 ```
 
 ## Testing

Cargo.toml

@@ -65,10 +65,12 @@ features = ["with-syntex"]
 version = "0.29"
 
 [features]
-assert_no_dangling_items = []
 default = ["logging"]
-testing_only_llvm_stable = []
 logging = ["env_logger", "log"]
 static = []
-# This feature only exists for CI -- don't use it!
-docs_ = []
+
+# These features only exist for CI testing -- don't use them if you're not hacking
+# on bindgen!
+testing_only_assert_no_dangling_items = []
+testing_only_docs = []
+testing_only_llvm_stable = []

ci/assert-docs.sh

@@ -3,4 +3,4 @@
 set -xeu
 cd "$(dirname "$0")/.."
 
-cargo build --features "$BINDGEN_FEATURES docs_"
+cargo build --features "$BINDGEN_FEATURES testing_only_docs"

ci/test.sh

@@ -6,10 +6,10 @@ cd "$(dirname "$0")/.."
 # Regenerate the test headers' bindings in debug and release modes, and assert
 # that we always get the expected generated bindings.
 
-cargo test --features "$BINDGEN_FEATURES assert_no_dangling_items"
+cargo test --features "$BINDGEN_FEATURES testing_only_assert_no_dangling_items"
 ./ci/assert-no-diff.sh
 
-cargo test --release --features "$BINDGEN_FEATURES assert_no_dangling_items"
+cargo test --release --features "$BINDGEN_FEATURES testing_only_assert_no_dangling_items"
 ./ci/assert-no-diff.sh
 
 # Now test the expectations' size and alignment tests.

src/ir/context.rs

@@ -584,9 +584,12 @@ impl<'ctx> BindgenContext<'ctx> {
         ret
     }
 
-    /// This function trying to find any dangling references inside of `items`
+    /// When the `testing_only_assert_no_dangling_items` feature is enabled,
+    /// this function walks the IR graph and asserts that we do not have any
+    /// edges referencing an ItemId for which we do not have an associated IR
+    /// item.
     fn assert_no_dangling_references(&self) {
-        if cfg!(feature = "assert_no_dangling_items") {
+        if cfg!(feature = "testing_only_assert_no_dangling_items") {
             for _ in self.assert_no_dangling_item_traversal() {
                 // The iterator's next method does the asserting for us.
             }

src/lib.rs

@@ -38,15 +38,15 @@ extern crate log;
 mod log_stubs;
 
 // A macro to declare an internal module for which we *must* provide
-// documentation for. If we are building with the "docs_" feature, then the
-// module is declared public, and our `#![deny(missing_docs)]` pragma applies to
-// it. This feature is used in CI, so we won't let anything slip by
+// documentation for. If we are building with the "testing_only_docs" feature,
+// then the module is declared public, and our `#![deny(missing_docs)]` pragma
+// applies to it. This feature is used in CI, so we won't let anything slip by
 // undocumented. Normal builds, however, will leave the module private, so that
 // we don't expose internals to library consumers.
 macro_rules! doc_mod {
     ($m:ident, $doc_mod_name:ident) => {
         cfg_if! {
-            if #[cfg(feature = "docs_")] {
+            if #[cfg(feature = "testing_only_docs")] {
                 pub mod $doc_mod_name {
                     //! Autogenerated documentation module.
                     pub use super::$m::*;