run test suite also against libstd with full MIR

.travis.yml

@@ -6,16 +6,29 @@ before_script:
 - rustup target add i686-unknown-linux-gnu
 - rustup target add i686-pc-windows-gnu
 - rustup target add i686-pc-windows-msvc
+- rustup component add rust-src
+- chmod +x -R ~/.rustup/toolchains/*/lib/rustlib/src/rust/src/jemalloc/include/jemalloc/
+- cargo install xargo
+- export RUST_SYSROOT=$HOME/rust
 script:
 - |
-  export RUST_SYSROOT=$HOME/rust &&
+  # Test plain miri
   cargo build &&
   cargo test &&
-  cargo install &&
+  cargo install
+- |
+  # Test cargo miri
   cd cargo-miri-test &&
   cargo miri &&
   cargo miri test &&
   cd ..
+- |
+  # get ourselves a MIR-ful libstd
+  cd xargo &&
+  RUSTFLAGS='-Zalways-encode-mir' xargo build &&
+  cd .. &&
+  # and run the tests with it
+  MIRI_SYSROOT=~/.xargo/HOST cargo test
 notifications:
   email:
     on_success: never

README.md

@@ -71,7 +71,7 @@ RUSTFLAGS='-Zalways-encode-mir' xargo build
 Now you can run miri against the libstd compiled by xargo:
 
 ```sh
-cargo run --bin miri -- --sysroot ~/.xargo/HOST tests/run-pass/vecs.rs
+MIRI_SYSROOT=~/.xargo/HOST cargo run --bin miri tests/run-pass/vecs.rs
 ```
 
 Notice that you will have to re-run the last step of the preparations above when

src/bin/miri.rs

@@ -175,6 +175,10 @@ fn init_logger() {
 }
 
 fn find_sysroot() -> String {
+    if let Ok(sysroot) = std::env::var("MIRI_SYSROOT") {
+        return sysroot;
+    }
+
     // Taken from https://github.com/Manishearth/rust-clippy/pull/911.
     let home = option_env!("RUSTUP_HOME").or(option_env!("MULTIRUST_HOME"));
     let toolchain = option_env!("RUSTUP_TOOLCHAIN").or(option_env!("MULTIRUST_TOOLCHAIN"));

tests/compile-fail/stack_limit.rs

 #![feature(custom_attribute, attr_literals)]
 #![miri(stack_limit=16)]
 
+//error-pattern: reached the configured maximum number of stack frames
+
 fn bar() {
     foo();
 }
 
 fn foo() {
-    cake(); //~ ERROR reached the configured maximum number of stack frames
+    cake();
 }
 
 fn cake() {
-    flubber(3);
-}
-
-fn flubber(i: u32) {
-    if i > 0 {
-        flubber(i-1);
-    } else {
-        bar();
-    }
+    bar();
 }
 
 fn main() {

tests/compiletest.rs

@@ -65,14 +65,16 @@ fn for_all_targets<F: FnMut(String)>(sysroot: &Path, mut f: F) {
 
 #[test]
 fn compile_test() {
-    let sysroot = std::process::Command::new("rustc")
-        .arg("--print")
-        .arg("sysroot")
-        .output()
-        .expect("rustc not found")
-        .stdout;
-    let sysroot = std::str::from_utf8(&sysroot).expect("sysroot is not utf8").trim();
-    let sysroot = &Path::new(&sysroot);
+    let sysroot = std::env::var("MIRI_SYSROOT").unwrap_or_else(|_| {
+        let sysroot = std::process::Command::new("rustc")
+            .arg("--print")
+            .arg("sysroot")
+            .output()
+            .expect("rustc not found")
+            .stdout;
+        String::from_utf8(sysroot).expect("sysroot is not utf8")
+    });
+    let sysroot = &Path::new(sysroot.trim());
     let host = std::process::Command::new("rustc")
         .arg("-vV")
         .output()