Auto merge of #6254 - ehuss:fix-travis-slow, r=alexcrichton

Fix slow MacOS Travis issue.

OS X 10.13 images on Travis are running very slow and causing timeouts. This PR does two things:

- Use OS X 10.12 (`xode9.2`) which is much faster.
- Implement a change to the testsuite to handle 1-second resolution mtimes on HFS. When a test executes cargo multiple times, and the first run finishes in under 1 second, the second one will think it needs to rebuild because the mtime of the files equals the mtime of the output. This change forces the mtime of every project to be created 1 second in the past. Tests that are still sensitive to mtimes are adjusted on a case-by-case basis.

Closes #6239, Closes #5940

.travis.yml

@@ -22,6 +22,7 @@ matrix:
     - env: TARGET=x86_64-apple-darwin
            ALT=i686-apple-darwin
       os: osx
+      osx_image: xcode9.2
       if: branch != master OR type = pull_request
 
     - env: TARGET=x86_64-unknown-linux-gnu

tests/testsuite/metabuild.rs

@@ -2,7 +2,8 @@ use glob::glob;
 use serde_json;
 use std::str;
 use support::{
-    basic_lib_manifest, basic_manifest, project, registry::Package, rustc_host, Project,
+    basic_lib_manifest, basic_manifest, is_coarse_mtime, project, registry::Package, rustc_host,
+    Project,
 };
 
 #[test]
@@ -212,6 +213,14 @@ fn metabuild_lib_name() {
 
 #[test]
 fn metabuild_fresh() {
+    if is_coarse_mtime() {
+        // This test doesn't work on coarse mtimes very well. Because the
+        // metabuild script is created at build time, its mtime is almost
+        // always equal to the mtime of the output. The second call to `build`
+        // will then think it needs to be rebuilt when it should be fresh.
+        return;
+    }
+
     // Check that rebuild is fresh.
     let p = project()
         .file(

tests/testsuite/support/mod.rs

@@ -113,11 +113,12 @@ use std::os;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Output};
 use std::str;
-use std::time::Duration;
+use std::time::{self, Duration};
 use std::usize;
 
 use cargo;
 use cargo::util::{CargoResult, ProcessBuilder, ProcessError, Rustc};
+use filetime;
 use serde_json::{self, Value};
 use url::Url;
 
@@ -279,8 +280,19 @@ impl ProjectBuilder {
             self._file(Path::new("Cargo.toml"), &basic_manifest("foo", "0.0.1"))
         }
 
+        let past = time::SystemTime::now() - Duration::new(1, 0);
+        let ftime = filetime::FileTime::from_system_time(past);
+
         for file in self.files.iter() {
             file.mk();
+            if is_coarse_mtime() {
+                // Place the entire project 1 second in the past to ensure
+                // that if cargo is called multiple times, the 2nd call will
+                // see targets as "fresh". Without this, if cargo finishes in
+                // under 1 second, the second call will see the mtime of
+                // source == mtime of output and consider it dirty.
+                filetime::set_file_times(&file.path, ftime, ftime).unwrap();
+            }
         }
 
         for symlink in self.symlinks.iter() {
@@ -1510,3 +1522,11 @@ pub fn git_process(s: &str) -> ProcessBuilder {
 pub fn sleep_ms(ms: u64) {
     ::std::thread::sleep(Duration::from_millis(ms));
 }
+
+/// Returns true if the local filesystem has low-resolution mtimes.
+pub fn is_coarse_mtime() -> bool {
+    // This should actually be a test that $CARGO_TARGET_DIR is on an HFS
+    // filesystem, (or any filesystem with low-resolution mtimes). However,
+    // that's tricky to detect, so for now just deal with CI.
+    cfg!(target_os = "macos") && env::var("CI").is_ok()
+}