From f556a9bbb422e86c76334fe3fe0a3c0382707946 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Thu, 12 Jul 2018 20:19:42 -0500
Subject: [PATCH] test source importing this crate

---
 library/compiler-builtins/libm/Cargo.toml    |  2 +-
 library/compiler-builtins/libm/README.md     |  5 ++++-
 library/compiler-builtins/libm/cb/Cargo.toml |  6 ++++++
 library/compiler-builtins/libm/cb/src/lib.rs |  9 +++++++++
 library/compiler-builtins/libm/ci/script.sh  | 10 ++++++++++
 5 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 library/compiler-builtins/libm/cb/Cargo.toml
 create mode 100644 library/compiler-builtins/libm/cb/src/lib.rs

diff --git a/library/compiler-builtins/libm/Cargo.toml b/library/compiler-builtins/libm/Cargo.toml
index 96bc290fb320..e3498eed0381 100644
--- a/library/compiler-builtins/libm/Cargo.toml
+++ b/library/compiler-builtins/libm/Cargo.toml
@@ -4,4 +4,4 @@ version = "0.1.0"
 authors = ["Jorge Aparicio <jorge@japaric.io>"]
 
 [workspace]
-members = ["test-generator"]
\ No newline at end of file
+members = ["cb", "test-generator"]
\ No newline at end of file
diff --git a/library/compiler-builtins/libm/README.md b/library/compiler-builtins/libm/README.md
index 55f4654346e6..cb29baf63a7b 100644
--- a/library/compiler-builtins/libm/README.md
+++ b/library/compiler-builtins/libm/README.md
@@ -32,7 +32,7 @@ $ TARGET=armv7-unknown-linux-gnueabihf bash ci/script.sh
 - Pick your favorite math function from the [issue tracker].
 - Look for the C implementation of the function in the [MUSL source code][src].
 - Copy paste the C code into a Rust file in the `src/math` directory and adjust `src/math/mod.rs`
-  accordingly.
+  accordingly. Also, uncomment the corresponding trait method in `src/lib.rs`.
 - Run `cargo watch check` and fix the compiler errors.
 - Tweak the bottom of `test-generator/src/main.rs` to add your function to the test suite.
 - If you can, run the test suite locally. If you can't, no problem! Your PR will be tested
@@ -49,6 +49,9 @@ Check [PR #2] for an example.
 
 ### Notes
 
+- Only use relative imports within the `math` directory / module, e.g. `use self::fabs::fabs` or
+`use super::isnanf`. Absolute imports from core are OK, e.g. `use core::u64`.
+
 - To reinterpret a float as an integer use the `to_bits` method. The MUSL code uses the
   `GET_FLOAT_WORD` macro, or a union, to do this operation.
 
diff --git a/library/compiler-builtins/libm/cb/Cargo.toml b/library/compiler-builtins/libm/cb/Cargo.toml
new file mode 100644
index 000000000000..40e75dd22fd1
--- /dev/null
+++ b/library/compiler-builtins/libm/cb/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "cb"
+version = "0.1.0"
+authors = ["Jorge Aparicio <jorge@japaric.io>"]
+
+[dependencies]
diff --git a/library/compiler-builtins/libm/cb/src/lib.rs b/library/compiler-builtins/libm/cb/src/lib.rs
new file mode 100644
index 000000000000..439ba7dc4e63
--- /dev/null
+++ b/library/compiler-builtins/libm/cb/src/lib.rs
@@ -0,0 +1,9 @@
+//! Fake compiler-builtins crate
+//!
+//! This is used to test that we can source import `libm` into the compiler-builtins crate.
+
+#![allow(dead_code)]
+#![no_std]
+
+#[path = "../../src/math/mod.rs"]
+mod libm;
diff --git a/library/compiler-builtins/libm/ci/script.sh b/library/compiler-builtins/libm/ci/script.sh
index ee2e458cc036..3db6bfeb12d9 100644
--- a/library/compiler-builtins/libm/ci/script.sh
+++ b/library/compiler-builtins/libm/ci/script.sh
@@ -1,11 +1,21 @@
 set -euxo pipefail
 
 main() {
+    # quick check
+    cargo check
+
+    # check that we can source import libm into compiler-builtins
+    cargo check --package cb
+
+    # generate tests
     cargo run --package test-generator --target x86_64-unknown-linux-musl
+
     if cargo fmt --version >/dev/null 2>&1; then
         # nicer syntax error messages (if any)
         cargo fmt
     fi
+
+    # run tests
     cross test --target $TARGET --release
 
     # TODO need to fix overflow issues (cf. issue #4)