Remove the in-tree flate crate

A long time coming this commit removes the `flate` crate in favor of the
`flate2` crate on crates.io. The functionality in `flate2` originally flowered
out of `flate` itself and is additionally the namesake for the crate. This will
leave a gap in the naming (there's not `flate` crate), which will likely cause a
particle collapse of some form somewhere.

Author: alexcrichton

COPYRIGHT

@@ -22,12 +22,6 @@ The Rust Project includes packages written by third parties.
 The following third party packages are included, and carry
 their own copyright notices and license terms:
 
-* The src/rt/miniz.c file, carrying an implementation of
-  RFC1950/RFC1951 DEFLATE, by Rich Geldreich
-  <[email protected]>. All uses of this file are
-  permitted by the embedded "unlicense" notice
-  (effectively: public domain with warranty disclaimer).
-
 * LLVM. Code for this package is found in src/llvm.
 
     Copyright (c) 2003-2013 University of Illinois at

src/libflate/Cargo.toml

@@ -22,3 +22,32 @@ rustc_errors = { path = "../librustc_errors" }
 serialize = { path = "../libserialize" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
+
+# Note that these dependencies are a lie, they're just here to get linkage to
+# work.
+#
+# We're creating a bunch of dylibs for the compiler but we're also compiling a
+# bunch of crates.io crates. Everything in the compiler is compiled as an
+# rlib/dylib pair but all crates.io crates tend to just be rlibs. This means
+# we've got a problem for dependency graphs that look like:
+#
+#           foo - rustc_trans
+#         /                  \
+#   rustc                     ---- rustc_driver
+#         \                     /
+#           foo - rustc_metadata
+#
+# Here the crate `foo` is linked into the `rustc_trans` and the
+# `rustc_metadata` dylibs, meaning we've got duplicate copies! When we then
+# go to link `rustc_driver` the compiler notices this and gives us a compiler
+# error.
+#
+# To work around this problem we just add these crates.io dependencies to the
+# `rustc` crate which is a shared dependency above. That way the crate `foo`
+# shows up in the dylib for the `rustc` crate, deduplicating it and allowing
+# crates like `rustc_trans` to use `foo` *through* the `rustc` crate.
+#
+# tl;dr; this is not needed to get `rustc` to compile, but if you remove it then
+#        later crate stop compiling. If you can remove this and everything
+#        compiles, then please feel free to do so!
+flate2 = "0.2"

src/libflate/build.rs

@@ -63,6 +63,8 @@ extern crate syntax_pos;
 
 extern crate serialize as rustc_serialize; // used by deriving
 
+extern crate flate2;
+
 #[macro_use]
 mod macros;
 

src/libflate/lib.rs

@@ -9,7 +9,7 @@ path = "lib.rs"
 crate-type = ["dylib"]
 
 [dependencies]
-flate = { path = "../libflate" }
+flate2 = "0.2"
 log = "0.3"
 owning_ref = "0.3.3"
 proc_macro = { path = "../libproc_macro" }

src/librustc/Cargo.toml

@@ -33,7 +33,7 @@ extern crate log;
 #[macro_use]
 extern crate syntax;
 extern crate syntax_pos;
-extern crate flate;
+extern crate flate2;
 extern crate serialize as rustc_serialize; // used by deriving
 extern crate owning_ref;
 extern crate rustc_errors as errors;

src/librustc/lib.rs

@@ -242,7 +242,7 @@ use std::io::{self, Read};
 use std::path::{Path, PathBuf};
 use std::time::Instant;
 
-use flate;
+use flate2::read::ZlibDecoder;
 use owning_ref::{ErasedBoxRef, OwningRef};
 
 pub struct CrateMismatch {
@@ -861,8 +861,9 @@ fn get_metadata_section_imp(target: &Target,
             // Header is okay -> inflate the actual metadata
             let compressed_bytes = &buf[header_len..];
             debug!("inflating {} bytes of compressed metadata", compressed_bytes.len());
-            match flate::inflate_bytes(compressed_bytes) {
-                Ok(inflated) => {
+            let mut inflated = Vec::new();
+            match ZlibDecoder::new(compressed_bytes).read_to_end(&mut inflated) {
+                Ok(_) => {
                     let buf = unsafe { OwningRef::new_assert_stable_address(inflated) };
                     buf.map_owner_box().erase_owner()
                 }

src/librustc_metadata/Cargo.toml

@@ -10,7 +10,7 @@ crate-type = ["dylib"]
 test = false
 
 [dependencies]
-flate = { path = "../libflate" }
+flate2 = "0.2"
 log = "0.3"
 owning_ref = "0.3.3"
 rustc = { path = "../librustc" }