Rollup merge of rust-lang#39142 - nikomatsakis:issue-38973, r=brson

run rustdoc tests in the same sort of thread rustc runs in

Not sure yet if this is the problem in rust-lang#38973 but seems like an improvement regardless.

r? @brson

src/librustc_driver/lib.rs

@@ -82,6 +82,7 @@ use rustc::util::common::time;
 
 use serialize::json::ToJson;
 
+use std::any::Any;
 use std::cmp::max;
 use std::cmp::Ordering::Equal;
 use std::default::Default;
@@ -1018,15 +1019,34 @@ fn parse_crate_attrs<'a>(sess: &'a Session, input: &Input) -> PResult<'a, Vec<as
     }
 }
 
+/// Runs `f` in a suitable thread for running `rustc`; returns a
+/// `Result` with either the return value of `f` or -- if a panic
+/// occurs -- the panic value.
+pub fn in_rustc_thread<F, R>(f: F) -> Result<R, Box<Any + Send>>
+    where F: FnOnce() -> R + Send + 'static,
+          R: Send + 'static,
+{
+    // Temporarily have stack size set to 16MB to deal with nom-using crates failing
+    const STACK_SIZE: usize = 16 * 1024 * 1024; // 16MB
+
+    let mut cfg = thread::Builder::new().name("rustc".to_string());
+
+    // FIXME: Hacks on hacks. If the env is trying to override the stack size
+    // then *don't* set it explicitly.
+    if env::var_os("RUST_MIN_STACK").is_none() {
+        cfg = cfg.stack_size(STACK_SIZE);
+    }
+
+    let thread = cfg.spawn(f);
+    thread.unwrap().join()
+}
+
 /// Run a procedure which will detect panics in the compiler and print nicer
 /// error messages rather than just failing the test.
 ///
 /// The diagnostic emitter yielded to the procedure should be used for reporting
 /// errors of the compiler.
 pub fn monitor<F: FnOnce() + Send + 'static>(f: F) {
-    // Temporarily have stack size set to 16MB to deal with nom-using crates failing
-    const STACK_SIZE: usize = 16 * 1024 * 1024; // 16MB
-
     struct Sink(Arc<Mutex<Vec<u8>>>);
     impl Write for Sink {
         fn write(&mut self, data: &[u8]) -> io::Result<usize> {
@@ -1040,20 +1060,12 @@ pub fn monitor<F: FnOnce() + Send + 'static>(f: F) {
     let data = Arc::new(Mutex::new(Vec::new()));
     let err = Sink(data.clone());
 
-    let mut cfg = thread::Builder::new().name("rustc".to_string());
-
-    // FIXME: Hacks on hacks. If the env is trying to override the stack size
-    // then *don't* set it explicitly.
-    if env::var_os("RUST_MIN_STACK").is_none() {
-        cfg = cfg.stack_size(STACK_SIZE);
-    }
-
-    let thread = cfg.spawn(move || {
-         io::set_panic(Some(box err));
-         f()
-     });
+    let result = in_rustc_thread(move || {
+        io::set_panic(Some(box err));
+        f()
+    });
 
-     if let Err(value) = thread.unwrap().join() {
+    if let Err(value) = result {
         // Thread panicked without emitting a fatal diagnostic
         if !value.is::<errors::FatalError>() {
             let emitter =

src/librustdoc/test.rs

@@ -29,7 +29,7 @@ use rustc::session::config::{OutputType, OutputTypes, Externs};
 use rustc::session::search_paths::{SearchPaths, PathKind};
 use rustc_back::dynamic_lib::DynamicLibrary;
 use rustc_back::tempdir::TempDir;
-use rustc_driver::{driver, Compilation};
+use rustc_driver::{self, driver, Compilation};
 use rustc_driver::driver::phase_2_configure_and_expand;
 use rustc_metadata::cstore::CStore;
 use rustc_resolve::MakeGlobMap;
@@ -429,19 +429,26 @@ impl Collector {
                 should_panic: testing::ShouldPanic::No,
             },
             testfn: testing::DynTestFn(box move |()| {
-                runtest(&test,
-                        &cratename,
-                        cfgs,
-                        libs,
-                        externs,
-                        should_panic,
-                        no_run,
-                        as_test_harness,
-                        compile_fail,
-                        error_codes,
-                        &opts,
-                        maybe_sysroot);
-            })
+                match {
+                    rustc_driver::in_rustc_thread(move || {
+                        runtest(&test,
+                                &cratename,
+                                cfgs,
+                                libs,
+                                externs,
+                                should_panic,
+                                no_run,
+                                as_test_harness,
+                                compile_fail,
+                                error_codes,
+                                &opts,
+                                maybe_sysroot)
+                    })
+                } {
+                    Ok(()) => (),
+                    Err(err) => panic::resume_unwind(err),
+                }
+            }),
         });
     }