Rollup merge of #48143 - nikomatsakis:termination_trait_in_tests, r=eddyb

Termination trait in tests

Support the `Termination` trait in unit tests (cc https://github.com/rust-lang/rust/issues/43301)

Also, a drive-by fix for #47075.

This is joint work with @bkchr.

src/librustc_driver/driver.rs

@@ -818,7 +818,8 @@ pub fn phase_2_configure_and_expand_inner<'a, F>(sess: &'a Session,
                                          &mut resolver,
                                          sess.opts.test,
                                          krate,
-                                         sess.diagnostic())
+                                         sess.diagnostic(),
+                                         &sess.features.borrow())
     });
 
     // If we're actually rustdoc then there's no need to actually compile

src/libstd/lib.rs

@@ -500,11 +500,6 @@ mod memchr;
 // The runtime entry point and a few unstable public functions used by the
 // compiler
 pub mod rt;
-// The trait to support returning arbitrary types in the main function
-mod termination;
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-pub use self::termination::Termination;
 
 // Include a number of private modules that exist solely to provide
 // the rustdoc documentation for primitive types. Using `include!`

src/libstd/process.rs

@@ -1392,6 +1392,73 @@ pub fn id() -> u32 {
     ::sys::os::getpid()
 }
 
+#[cfg(target_arch = "wasm32")]
+mod exit {
+    pub const SUCCESS: i32 = 0;
+    pub const FAILURE: i32 = 1;
+}
+#[cfg(not(target_arch = "wasm32"))]
+mod exit {
+    use libc;
+    pub const SUCCESS: i32 = libc::EXIT_SUCCESS;
+    pub const FAILURE: i32 = libc::EXIT_FAILURE;
+}
+
+/// A trait for implementing arbitrary return types in the `main` function.
+///
+/// The c-main function only supports to return integers as return type.
+/// So, every type implementing the `Termination` trait has to be converted
+/// to an integer.
+///
+/// The default implementations are returning `libc::EXIT_SUCCESS` to indicate
+/// a successful execution. In case of a failure, `libc::EXIT_FAILURE` is returned.
+#[cfg_attr(not(test), lang = "termination")]
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+#[rustc_on_unimplemented =
+  "`main` can only return types that implement {Termination}, not `{Self}`"]
+pub trait Termination {
+    /// Is called to get the representation of the value as status code.
+    /// This status code is returned to the operating system.
+    fn report(self) -> i32;
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl Termination for () {
+    fn report(self) -> i32 { exit::SUCCESS }
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl<T: Termination, E: fmt::Debug> Termination for Result<T, E> {
+    fn report(self) -> i32 {
+        match self {
+            Ok(val) => val.report(),
+            Err(err) => {
+                eprintln!("Error: {:?}", err);
+                exit::FAILURE
+            }
+        }
+    }
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl Termination for ! {
+    fn report(self) -> i32 { unreachable!(); }
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl Termination for bool {
+    fn report(self) -> i32 {
+        if self { exit::SUCCESS } else { exit::FAILURE }
+    }
+}
+
+#[unstable(feature = "termination_trait_lib", issue = "43301")]
+impl Termination for i32 {
+    fn report(self) -> i32 {
+        self
+    }
+}
+
 #[cfg(all(test, not(any(target_os = "cloudabi", target_os = "emscripten"))))]
 mod tests {
     use io::prelude::*;

src/libstd/rt.rs

@@ -68,7 +68,7 @@ fn lang_start_internal(main: &(Fn() -> i32 + Sync + ::panic::RefUnwindSafe),
 
 #[cfg(not(test))]
 #[lang = "start"]
-fn lang_start<T: ::termination::Termination + 'static>
+fn lang_start<T: ::process::Termination + 'static>
     (main: fn() -> T, argc: isize, argv: *const *const u8) -> isize
 {
     lang_start_internal(&move || main().report(), argc, argv)

src/libstd/termination.rs

@@ -1,77 +0,0 @@
-// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-use fmt::Debug;
-#[cfg(target_arch = "wasm32")]
-mod exit {
-    pub const SUCCESS: i32 = 0;
-    pub const FAILURE: i32 = 1;
-}
-#[cfg(not(target_arch = "wasm32"))]
-mod exit {
-    use libc;
-    pub const SUCCESS: i32 = libc::EXIT_SUCCESS;
-    pub const FAILURE: i32 = libc::EXIT_FAILURE;
-}
-
-/// A trait for implementing arbitrary return types in the `main` function.
-///
-/// The c-main function only supports to return integers as return type.
-/// So, every type implementing the `Termination` trait has to be converted
-/// to an integer.
-///
-/// The default implementations are returning `libc::EXIT_SUCCESS` to indicate
-/// a successful execution. In case of a failure, `libc::EXIT_FAILURE` is returned.
-#[cfg_attr(not(test), lang = "termination")]
-#[unstable(feature = "termination_trait", issue = "43301")]
-#[rustc_on_unimplemented =
-  "`main` can only return types that implement {Termination}, not `{Self}`"]
-pub trait Termination {
-    /// Is called to get the representation of the value as status code.
-    /// This status code is returned to the operating system.
-    fn report(self) -> i32;
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl Termination for () {
-    fn report(self) -> i32 { exit::SUCCESS }
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl<T: Termination, E: Debug> Termination for Result<T, E> {
-    fn report(self) -> i32 {
-        match self {
-            Ok(val) => val.report(),
-            Err(err) => {
-                eprintln!("Error: {:?}", err);
-                exit::FAILURE
-            }
-        }
-    }
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl Termination for ! {
-    fn report(self) -> i32 { unreachable!(); }
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl Termination for bool {
-    fn report(self) -> i32 {
-        if self { exit::SUCCESS } else { exit::FAILURE }
-    }
-}
-
-#[unstable(feature = "termination_trait", issue = "43301")]
-impl Termination for i32 {
-    fn report(self) -> i32 {
-        self
-    }
-}

src/libsyntax/ext/build.rs

@@ -319,14 +319,8 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                 types: Vec<P<ast::Ty>>,
                 bindings: Vec<ast::TypeBinding> )
                 -> ast::Path {
-        use syntax::parse::token;
-
         let last_identifier = idents.pop().unwrap();
         let mut segments: Vec<ast::PathSegment> = Vec::new();
-        if global &&
-           !idents.first().map_or(false, |&ident| token::Ident(ident).is_path_segment_keyword()) {
-            segments.push(ast::PathSegment::crate_root(span));
-        }
 
         segments.extend(idents.into_iter().map(|i| ast::PathSegment::from_ident(i, span)));
         let parameters = if !lifetimes.is_empty() || !types.is_empty() || !bindings.is_empty() {
@@ -335,7 +329,9 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
             None
         };
         segments.push(ast::PathSegment { identifier: last_identifier, span, parameters });
-        ast::Path { span, segments }
+        let path = ast::Path { span, segments };
+
+        if global { path.default_to_global() } else { path }
     }
 
     /// Constructs a qualified path.

src/libsyntax/test.rs

@@ -32,6 +32,7 @@ use ext::build::AstBuilder;
 use ext::expand::ExpansionConfig;
 use ext::hygiene::{Mark, SyntaxContext};
 use fold::Folder;
+use feature_gate::Features;
 use util::move_map::MoveMap;
 use fold;
 use parse::{token, ParseSess};
@@ -63,6 +64,7 @@ struct TestCtxt<'a> {
     reexport_test_harness_main: Option<Symbol>,
     is_libtest: bool,
     ctxt: SyntaxContext,
+    features: &'a Features,
 
     // top-level re-export submodule, filled out after folding is finished
     toplevel_reexport: Option<Ident>,
@@ -74,7 +76,8 @@ pub fn modify_for_testing(sess: &ParseSess,
                           resolver: &mut Resolver,
                           should_test: bool,
                           krate: ast::Crate,
-                          span_diagnostic: &errors::Handler) -> ast::Crate {
+                          span_diagnostic: &errors::Handler,
+                          features: &Features) -> ast::Crate {
     // Check for #[reexport_test_harness_main = "some_name"] which
     // creates a `use some_name = __test::main;`. This needs to be
     // unconditional, so that the attribute is still marked as used in
@@ -84,7 +87,8 @@ pub fn modify_for_testing(sess: &ParseSess,
                                            "reexport_test_harness_main");
 
     if should_test {
-        generate_test_harness(sess, resolver, reexport_test_harness_main, krate, span_diagnostic)
+        generate_test_harness(sess, resolver, reexport_test_harness_main,
+                              krate, span_diagnostic, features)
     } else {
         krate
     }
@@ -265,16 +269,20 @@ fn generate_test_harness(sess: &ParseSess,
                          resolver: &mut Resolver,
                          reexport_test_harness_main: Option<Symbol>,
                          krate: ast::Crate,
-                         sd: &errors::Handler) -> ast::Crate {
+                         sd: &errors::Handler,
+                         features: &Features) -> ast::Crate {
     // Remove the entry points
     let mut cleaner = EntryPointCleaner { depth: 0 };
     let krate = cleaner.fold_crate(krate);
 
     let mark = Mark::fresh(Mark::root());
 
+    let mut econfig = ExpansionConfig::default("test".to_string());
+    econfig.features = Some(features);
+
     let cx = TestCtxt {
         span_diagnostic: sd,
-        ext_cx: ExtCtxt::new(sess, ExpansionConfig::default("test".to_string()), resolver),
+        ext_cx: ExtCtxt::new(sess, econfig, resolver),
         path: Vec::new(),
         testfns: Vec::new(),
         reexport_test_harness_main,
@@ -282,6 +290,7 @@ fn generate_test_harness(sess: &ParseSess,
         is_libtest: attr::find_crate_name(&krate.attrs).map(|s| s == "test").unwrap_or(false),
         toplevel_reexport: None,
         ctxt: SyntaxContext::empty().apply_mark(mark),
+        features,
     };
 
     mark.set_expn_info(ExpnInfo {
@@ -318,17 +327,24 @@ enum HasTestSignature {
 fn is_test_fn(cx: &TestCtxt, i: &ast::Item) -> bool {
     let has_test_attr = attr::contains_name(&i.attrs, "test");
 
-    fn has_test_signature(i: &ast::Item) -> HasTestSignature {
+    fn has_test_signature(cx: &TestCtxt, i: &ast::Item) -> HasTestSignature {
         match i.node {
             ast::ItemKind::Fn(ref decl, _, _, _, ref generics, _) => {
+                // If the termination trait is active, the compiler will check that the output
+                // type implements the `Termination` trait as `libtest` enforces that.
+                let output_matches = if cx.features.termination_trait {
+                    true
+                } else {
                     let no_output = match decl.output {
                         ast::FunctionRetTy::Default(..) => true,
                         ast::FunctionRetTy::Ty(ref t) if t.node == ast::TyKind::Tup(vec![]) => true,
                         _ => false
                     };
-            if decl.inputs.is_empty()
+
-                   && no_output
+                    no_output && !generics.is_parameterized()
-                   && !generics.is_parameterized() {
+                };
+
+                if decl.inputs.is_empty() && output_matches {
                     Yes
                 } else {
                     No
@@ -338,26 +354,43 @@ fn is_test_fn(cx: &TestCtxt, i: &ast::Item) -> bool {
         }
     }
 
-    if has_test_attr {
+    let has_test_signature = if has_test_attr {
         let diag = cx.span_diagnostic;
-        match has_test_signature(i) {
+        match has_test_signature(cx, i) {
-            Yes => {},
+            Yes => true,
-            No => diag.span_err(i.span, "functions used as tests must have signature fn() -> ()"),
+            No => {
-            NotEvenAFunction => diag.span_err(i.span,
+                if cx.features.termination_trait {
-                                              "only functions may be used as tests"),
+                    diag.span_err(i.span, "functions used as tests can not have any arguments");
+                } else {
+                    diag.span_err(i.span, "functions used as tests must have signature fn() -> ()");
                 }
+                false
+            },
+            NotEvenAFunction => {
+                diag.span_err(i.span, "only functions may be used as tests");
+                false
+            },
         }
+    } else {
+        false
+    };
 
-    has_test_attr && has_test_signature(i) == Yes
+    has_test_attr && has_test_signature
 }
 
 fn is_bench_fn(cx: &TestCtxt, i: &ast::Item) -> bool {
     let has_bench_attr = attr::contains_name(&i.attrs, "bench");
 
-    fn has_test_signature(i: &ast::Item) -> bool {
+    fn has_bench_signature(cx: &TestCtxt, i: &ast::Item) -> bool {
         match i.node {
             ast::ItemKind::Fn(ref decl, _, _, _, ref generics, _) => {
                 let input_cnt = decl.inputs.len();
+
+                // If the termination trait is active, the compiler will check that the output
+                // type implements the `Termination` trait as `libtest` enforces that.
+                let output_matches = if cx.features.termination_trait {
+                    true
+                } else {
                     let no_output = match decl.output {
                         ast::FunctionRetTy::Default(..) => true,
                         ast::FunctionRetTy::Ty(ref t) if t.node == ast::TyKind::Tup(vec![]) => true,
@@ -367,22 +400,32 @@ fn is_bench_fn(cx: &TestCtxt, i: &ast::Item) -> bool {
                         .filter(|param| param.is_type_param())
                         .count();
 
+                    no_output && tparm_cnt == 0
+                };
+
                 // NB: inadequate check, but we're running
                 // well before resolve, can't get too deep.
-                input_cnt == 1
+                input_cnt == 1 && output_matches
-                    && no_output && tparm_cnt == 0
             }
           _ => false
         }
     }
 
-    if has_bench_attr && !has_test_signature(i) {
+    let has_bench_signature = has_bench_signature(cx, i);
+
+    if has_bench_attr && !has_bench_signature {
         let diag = cx.span_diagnostic;
+
+        if cx.features.termination_trait {
+            diag.span_err(i.span, "functions used as benches must have signature \
+                                   `fn(&mut Bencher) -> impl Termination`");
+        } else {
             diag.span_err(i.span, "functions used as benches must have signature \
                                    `fn(&mut Bencher) -> ()`");
         }
+    }
 
-    has_bench_attr && has_test_signature(i)
+    has_bench_attr && has_bench_signature
 }
 
 fn is_ignored(i: &ast::Item) -> bool {
@@ -690,9 +733,12 @@ fn mk_test_desc_and_fn_rec(cx: &TestCtxt, test: &Test) -> P<ast::Expr> {
              field("should_panic", fail_expr),
              field("allow_fail", allow_fail_expr)]);
 
-
+    let mut visible_path = vec![];
-    let mut visible_path = match cx.toplevel_reexport {
+    if cx.features.extern_absolute_paths {
-        Some(id) => vec![id],
+        visible_path.push(keywords::Crate.ident());
+    }
+    match cx.toplevel_reexport {
+        Some(id) => visible_path.push(id),
         None => {
             let diag = cx.span_diagnostic;
             diag.bug("expected to find top-level re-export name, but found None");
@@ -700,9 +746,64 @@ fn mk_test_desc_and_fn_rec(cx: &TestCtxt, test: &Test) -> P<ast::Expr> {
     };
     visible_path.extend(path);
 
-    let fn_expr = ecx.expr_path(ecx.path_global(span, visible_path));
+    // Rather than directly give the test function to the test
+    // harness, we create a wrapper like one of the following:
+    //
+    //     || test::assert_test_result(real_function()) // for test
+    //     |b| test::assert_test_result(real_function(b)) // for bench
+    //
+    // this will coerce into a fn pointer that is specialized to the
+    // actual return type of `real_function` (Typically `()`, but not always).
+    let fn_expr = {
+        // construct `real_function()` (this will be inserted into the overall expr)
+        let real_function_expr = ecx.expr_path(ecx.path_global(span, visible_path));
+        // construct path `test::assert_test_result`
+        let assert_test_result = test_path("assert_test_result");
+        if test.bench {
+            // construct `|b| {..}`
+            let b_ident = Ident::with_empty_ctxt(Symbol::gensym("b"));
+            let b_expr = ecx.expr_ident(span, b_ident);
+            ecx.lambda(
+                span,
+                vec![b_ident],
+                // construct `assert_test_result(..)`
+                ecx.expr_call(
+                    span,
+                    ecx.expr_path(assert_test_result),
+                    vec![
+                        // construct `real_function(b)`
+                        ecx.expr_call(
+                            span,
+                            real_function_expr,
+                            vec![b_expr],
+                        )
+                    ],
+                ),
+            )
+        } else {
+            // construct `|| {..}`
+            ecx.lambda(
+                span,
+                vec![],
+                // construct `assert_test_result(..)`
+                ecx.expr_call(
+                    span,
+                    ecx.expr_path(assert_test_result),
+                    vec![
+                        // construct `real_function()`
+                        ecx.expr_call(
+                            span,
+                            real_function_expr,
+                            vec![],
+                        )
+                    ],
+                ),
+            )
+        }
+    };
 
     let variant_name = if test.bench { "StaticBenchFn" } else { "StaticTestFn" };
+
     // self::test::$variant_name($fn_expr)
     let testfn_expr = ecx.expr_call(span, ecx.expr_path(test_path(variant_name)), vec![fn_expr]);
 

src/libtest/lib.rs

@@ -40,6 +40,7 @@
 #![feature(set_stdio)]
 #![feature(panic_unwind)]
 #![feature(staged_api)]
+#![feature(termination_trait_lib)]
 
 extern crate getopts;
 extern crate term;
@@ -67,6 +68,7 @@ use std::io::prelude::*;
 use std::io;
 use std::iter::repeat;
 use std::path::PathBuf;
+use std::process::Termination;
 use std::sync::mpsc::{channel, Sender};
 use std::sync::{Arc, Mutex};
 use std::thread;
@@ -81,8 +83,8 @@ const QUIET_MODE_MAX_COLUMN: usize = 100; // insert a '\n' after 100 tests in qu
 pub mod test {
     pub use {Bencher, TestName, TestResult, TestDesc, TestDescAndFn, TestOpts, TrFailed,
              TrFailedMsg, TrIgnored, TrOk, Metric, MetricMap, StaticTestFn, StaticTestName,
-             DynTestName, DynTestFn, run_test, test_main, test_main_static, filter_tests,
+             DynTestName, DynTestFn, assert_test_result, run_test, test_main, test_main_static,
-             parse_opts, StaticBenchFn, ShouldPanic, Options};
+             filter_tests, parse_opts, StaticBenchFn, ShouldPanic, Options};
 }
 
 pub mod stats;
@@ -322,6 +324,13 @@ pub fn test_main_static(tests: &[TestDescAndFn]) {
     test_main(&args, owned_tests, Options::new())
 }
 
+/// Invoked when unit tests terminate. Should panic if the unit
+/// test is considered a failure. By default, invokes `report()`
+/// and checks for a `0` result.
+pub fn assert_test_result<T: Termination>(result: T) {
+    assert_eq!(result.report(), 0);
+}
+
 #[derive(Copy, Clone, Debug)]
 pub enum ColorConfig {
     AutoColor,

src/test/compile-fail/issue-12997-2.rs

@@ -15,6 +15,3 @@
 #[bench]
 fn bar(x: isize) { }
 //~^ ERROR mismatched types
-//~| expected type `for<'r> fn(&'r mut __test::test::Bencher)`
-//~| found type `fn(isize) {bar}`
-//~| expected mutable reference, found isize

src/test/compile-fail/rfc-1937-termination-trait/termination-trait-main-wrong-type.rs

@@ -10,6 +10,6 @@
 #![feature(termination_trait)]
 
 fn main() -> char {
-//~^ ERROR: the trait bound `char: std::Termination` is not satisfied
+//~^ ERROR: the trait bound `char: std::process::Termination` is not satisfied
     ' '
 }

src/test/compile-fail/rfc-1937-termination-trait/termination-trait-not-satisfied.rs

@@ -12,6 +12,6 @@
 
 struct ReturnType {}
 
-fn main() -> ReturnType { //~ ERROR `ReturnType: std::Termination` is not satisfied
+fn main() -> ReturnType { //~ ERROR `ReturnType: std::process::Termination` is not satisfied
     ReturnType {}
 }

src/test/run-fail/rfc-1937-termination-trait/termination-trait-for-never.rs

@@ -1,4 +1,4 @@
-// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -10,8 +10,8 @@
 
 #![feature(termination_trait)]
 
-use std::io::Error;
+// error-pattern:oh, dear
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> ! {
-    Ok(())
+    panic!("oh, dear");
 }

src/test/run-pass/rfc-1937-termination-trait/termination-trait-in-test.rs

@@ -0,0 +1,43 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags: --test
+
+#![feature(termination_trait)]
+#![feature(test)]
+
+extern crate test;
+use std::num::ParseIntError;
+use test::Bencher;
+
+#[test]
+fn is_a_num() -> Result<(), ParseIntError> {
+    let _: u32 = "22".parse()?;
+    Ok(())
+}
+
+#[test]
+#[should_panic]
+fn not_a_num() -> Result<(), ParseIntError> {
+    let _: u32 = "abc".parse()?;
+    Ok(())
+}
+
+#[bench]
+fn test_a_positive_bench(_: &mut Bencher) -> Result<(), ParseIntError> {
+    Ok(())
+}
+
+#[bench]
+#[should_panic]
+fn test_a_neg_bench(_: &mut Bencher) -> Result<(), ParseIntError> {
+    let _: u32 = "abc".parse()?;
+    Ok(())
+}

src/test/run-pass/rfc-2126-extern-absolute-paths/test.rs

@@ -0,0 +1,21 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Check that `#[test]` works with extern-absolute-paths enabled.
+//
+// Regression test for #47075.
+
+// compile-flags: --test
+
+#![feature(extern_absolute_paths)]
+
+#[test]
+fn test() {
+}