add tests for macro trailing commas

Author: ExpHP

src/test/compile-fail/macro-comma-behavior.rs

@@ -0,0 +1,101 @@
+// Copyright 2018 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.
+
+// Companion test to the similarly-named file in run-pass.
+
+// compile-flags: -C debug_assertions=yes
+// revisions: std core
+
+#![cfg_attr(core, no_std)]
+
+#[cfg(std)] use std::fmt;
+#[cfg(core)] use core::fmt;
+
+// (see documentation of the similarly-named test in run-pass)
+fn to_format_or_not_to_format() {
+    let falsum = || false;
+
+    // assert!(true, "{}",); // see run-pass
+
+    assert_eq!(1, 1, "{}",);
+    //[core]~^ ERROR no arguments
+    //[std]~^^ ERROR no arguments
+    assert_ne!(1, 2, "{}",);
+    //[core]~^ ERROR no arguments
+    //[std]~^^ ERROR no arguments
+
+    // debug_assert!(true, "{}",); // see run-pass
+
+    debug_assert_eq!(1, 1, "{}",);
+    //[core]~^ ERROR no arguments
+    //[std]~^^ ERROR no arguments
+    debug_assert_ne!(1, 2, "{}",);
+    //[core]~^ ERROR no arguments
+    //[std]~^^ ERROR no arguments
+
+    #[cfg(std)] {
+        eprint!("{}",);
+        //[std]~^ ERROR no arguments
+    }
+
+    #[cfg(std)] {
+        // FIXME: compile-fail says "expected error not found" even though
+        //        rustc does emit an error
+        // eprintln!("{}",);
+        // <DISABLED> [std]~^ ERROR no arguments
+    }
+
+    #[cfg(std)] {
+        format!("{}",);
+        //[std]~^ ERROR no arguments
+    }
+
+    format_args!("{}",);
+    //[core]~^ ERROR no arguments
+    //[std]~^^ ERROR no arguments
+
+    // if falsum() { panic!("{}",); } // see run-pass
+
+    #[cfg(std)] {
+        print!("{}",);
+        //[std]~^ ERROR no arguments
+    }
+
+    #[cfg(std)] {
+        // FIXME: compile-fail says "expected error not found" even though
+        //        rustc does emit an error
+        // println!("{}",);
+        // <DISABLED> [std]~^ ERROR no arguments
+    }
+
+    unimplemented!("{}",);
+    //[core]~^ ERROR no arguments
+    //[std]~^^ ERROR no arguments
+
+    // if falsum() { unreachable!("{}",); } // see run-pass
+
+    struct S;
+    impl fmt::Display for S {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            write!(f, "{}",)?;
+            //[core]~^ ERROR no arguments
+            //[std]~^^ ERROR no arguments
+
+            // FIXME: compile-fail says "expected error not found" even though
+            //        rustc does emit an error
+            // writeln!(f, "{}",)?;
+            // <DISABLED> [core]~^ ERROR no arguments
+            // <DISABLED> [std]~^^ ERROR no arguments
+            Ok(())
+        }
+    }
+}
+
+fn main() {}

src/test/compile-fail/macro-comma-support.rs

@@ -0,0 +1,20 @@
+// Copyright 2018 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.
+
+// This is a companion to the similarly-named test in run-pass.
+//
+// It tests macros that unavoidably produce compile errors.
+
+fn compile_error() {
+    compile_error!("lel"); //~ ERROR lel
+    compile_error!("lel",); //~ ERROR lel
+}
+
+fn main() {}

src/test/run-pass/auxiliary/macro-comma-support.rs

@@ -0,0 +1,11 @@
+// Copyright 2018 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.
+
+()

src/test/run-pass/macro-comma-behavior.rs

@@ -0,0 +1,98 @@
+// Copyright 2018 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.
+
+// Ideally, any macro call with a trailing comma should behave
+// identically to a call without the comma.
+//
+// This checks the behavior of macros with trailing commas in key
+// places where regressions in behavior seem highly possible (due
+// to it being e.g. a place where the addition of an argument
+// causes it to go down a code path with subtly different behavior).
+//
+// There is a companion test in compile-fail.
+
+// compile-flags: --test -C debug_assertions=yes
+// revisions: std core
+
+#![cfg_attr(core, no_std)]
+
+#[cfg(std)] use std::fmt;
+#[cfg(core)] use core::fmt;
+
+// an easy mistake in the implementation of 'assert!'
+// would cause this to say "explicit panic"
+#[test]
+#[should_panic(expected = "assertion failed")]
+fn assert_1arg() {
+    assert!(false,);
+}
+
+// same as 'assert_1arg'
+#[test]
+#[should_panic(expected = "assertion failed")]
+fn debug_assert_1arg() {
+    debug_assert!(false,);
+}
+
+// make sure we don't accidentally forward to `write!("text")`
+#[cfg(std)]
+#[test]
+fn writeln_2arg() {
+    use fmt::Write;
+
+    let mut s = String::new();
+    writeln!(&mut s, "hi",).unwrap();
+    assert_eq!(&s, "hi\n");
+}
+
+// A number of format_args-like macros have special-case treatment
+// for a single message string, which is not formatted.
+//
+// This test ensures that the addition of a trailing comma does not
+// suddenly cause these strings to get formatted when they otherwise
+// would not be. This is an easy mistake to make by having such a macro
+// accept ", $($tok:tt)*" instead of ", $($tok:tt)+" after its minimal
+// set of arguments.
+//
+// (Example: Issue #48042)
+#[test]
+fn to_format_or_not_to_format() {
+    // ("{}" is the easiest string to test because if this gets
+    // sent to format_args!, it'll simply fail to compile.
+    // "{{}}" is an example of an input that could compile and
+    // produce an incorrect program, but testing the panics
+    // would be burdensome.)
+    let falsum = || false;
+
+    assert!(true, "{}",);
+
+    // assert_eq!(1, 1, "{}",); // see compile-fail
+    // assert_ne!(1, 2, "{}",); // see compile-fail
+
+    debug_assert!(true, "{}",);
+
+    // debug_assert_eq!(1, 1, "{}",); // see compile-fail
+    // debug_assert_ne!(1, 2, "{}",); // see compile-fail
+    // eprint!("{}",); // see compile-fail
+    // eprintln!("{}",); // see compile-fail
+    // format!("{}",); // see compile-fail
+    // format_args!("{}",); // see compile-fail
+
+    if falsum() { panic!("{}",); }
+
+    // print!("{}",); // see compile-fail
+    // println!("{}",); // see compile-fail
+    // unimplemented!("{}",); // see compile-fail
+
+    if falsum() { unreachable!("{}",); }
+
+    // write!(&mut stdout, "{}",); // see compile-fail
+    // writeln!(&mut stdout, "{}",); // see compile-fail
+}