Avoid calling the column!() macro in panic

Author: est31

src/libcore/macros.rs

@@ -8,6 +8,16 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[macro_export]
+// This stability attribute is totally useless.
+#[stable(feature = "rust1", since = "1.0.0")]
+#[cfg(stage0)]
+macro_rules! __rust_unstable_column {
+    () => {
+        column!()
+    }
+}
+
 /// Entry point of thread panic, for details, see std::macros
 #[macro_export]
 #[allow_internal_unstable]
@@ -18,7 +28,7 @@ macro_rules! panic {
     );
     ($msg:expr) => ({
         static _MSG_FILE_LINE_COL: (&'static str, &'static str, u32, u32) =
-            ($msg, file!(), line!(), column!());
+            ($msg, file!(), line!(), __rust_unstable_column!());
         $crate::panicking::panic(&_MSG_FILE_LINE_COL)
     });
     ($fmt:expr, $($arg:tt)*) => ({
@@ -27,7 +37,7 @@ macro_rules! panic {
         // insufficient, since the user may have
         // `#[forbid(dead_code)]` and which cannot be overridden.
         static _MSG_FILE_LINE_COL: (&'static str, u32, u32) =
-            (file!(), line!(), column!());
+            (file!(), line!(), __rust_unstable_column!());
         $crate::panicking::panic_fmt(format_args!($fmt, $($arg)*), &_MSG_FILE_LINE_COL)
     });
 }

src/libstd/macros.rs

@@ -14,6 +14,16 @@
 //! library. Each macro is available for use when linking against the standard
 //! library.
 
+#[macro_export]
+// This stability attribute is totally useless.
+#[stable(feature = "rust1", since = "1.0.0")]
+#[cfg(stage0)]
+macro_rules! __rust_unstable_column {
+    () => {
+        column!()
+    }
+}
+
 /// The entry point for panic of Rust threads.
 ///
 /// This macro is used to inject panic into a Rust thread, causing the thread to
@@ -48,7 +58,8 @@ macro_rules! panic {
     ($msg:expr) => ({
         $crate::rt::begin_panic_new($msg, {
             // static requires less code at runtime, more constant data
-            static _FILE_LINE_COL: (&'static str, u32, u32) = (file!(), line!(), column!());
+            static _FILE_LINE_COL: (&'static str, u32, u32) = (file!(), line!(),
+                __rust_unstable_column!());
             &_FILE_LINE_COL
         })
     });
@@ -58,7 +69,8 @@ macro_rules! panic {
             // used inside a dead function. Just `#[allow(dead_code)]` is
             // insufficient, since the user may have
             // `#[forbid(dead_code)]` and which cannot be overridden.
-            static _FILE_LINE_COL: (&'static str, u32, u32) = (file!(), line!(), column!());
+            static _FILE_LINE_COL: (&'static str, u32, u32) = (file!(), line!(),
+                __rust_unstable_column!());
             &_FILE_LINE_COL
         })
     });

src/libsyntax_ext/lib.rs

@@ -89,6 +89,7 @@ pub fn register_builtins(resolver: &mut syntax::ext::base::Resolver,
     use syntax::ext::source_util::*;
     register! {
         line: expand_line,
+        __rust_unstable_column: expand_column,
         column: expand_column,
         file: expand_file,
         stringify: expand_stringify,

src/test/run-pass/issue-43057.rs

@@ -0,0 +1,23 @@
+// 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.
+
+#![allow(unused)]
+
+macro_rules! column {
+    ($i:ident) => {
+        $i
+    };
+}
+
+fn foo() -> ! {
+    panic!();
+}
+
+fn main() {}