Use backtrace formatting from the backtrace crate

Author: cramertj

Diff for: Cargo.lock

@@ -109,9 +109,9 @@ dependencies = [
 
 [[package]]
 name = "backtrace"
-version = "0.3.35"
+version = "0.3.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1371048253fa3bac6704bfd6bbfc922ee9bdcee8881330d40f308b81cc5adc55"
+checksum = "5180c5a20655b14a819b652fd2378fa5f1697b6c9ddad3e695c2f9cedf6df4e2"
 dependencies = [
  "backtrace-sys",
  "cfg-if",

Diff for: src/libstd/Cargo.toml

@@ -26,7 +26,7 @@ unwind = { path = "../libunwind" }
 hashbrown = { version = "0.5.0", features = ['rustc-dep-of-std'] }
 
 [dependencies.backtrace]
-version = "0.3.35"
+version = "0.3.37"
 default-features = false # don't use coresymbolication on OSX
 features = [
   "rustc-dep-of-std", # enable build support for integrating into libstd

Diff for: src/libstd/panicking.rs

@@ -158,7 +158,7 @@ pub fn take_hook() -> Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send> {
 
 fn default_hook(info: &PanicInfo<'_>) {
     #[cfg(feature = "backtrace")]
-    use crate::sys_common::backtrace;
+    use crate::sys_common::{backtrace as backtrace_mod};
 
     // If this is a double panic, make sure that we print a backtrace
     // for this panic. Otherwise only print it if logging is enabled.
@@ -167,9 +167,9 @@ fn default_hook(info: &PanicInfo<'_>) {
         let panics = update_panic_count(0);
 
         if panics >= 2 {
-            Some(backtrace::PrintFormat::Full)
+            Some(backtrace::PrintFmt::Full)
         } else {
-            backtrace::log_enabled()
+            backtrace_mod::log_enabled()
         }
     };
 
@@ -197,7 +197,7 @@ fn default_hook(info: &PanicInfo<'_>) {
             static FIRST_PANIC: AtomicBool = AtomicBool::new(true);
 
             if let Some(format) = log_backtrace {
-                let _ = backtrace::print(err, format);
+                let _ = backtrace_mod::print(err, format);
             } else if FIRST_PANIC.compare_and_swap(true, false, Ordering::SeqCst) {
                 let _ = writeln!(err, "note: run with `RUST_BACKTRACE=1` \
                                        environment variable to display a backtrace.");

Diff for: src/libstd/sys_common/backtrace.rs

@@ -2,23 +2,20 @@
 /// supported platforms.
 
 use crate::env;
+use crate::fmt;
 use crate::io;
 use crate::io::prelude::*;
-use crate::mem;
 use crate::path::{self, Path};
-use crate::ptr;
 use crate::sync::atomic::{self, Ordering};
 use crate::sys::mutex::Mutex;
 
-use backtrace::{BytesOrWideString, Frame, Symbol};
-
-pub const HEX_WIDTH: usize = 2 + 2 * mem::size_of::<usize>();
+use backtrace::{BacktraceFmt, BytesOrWideString, PrintFmt};
 
 /// Max number of frames to print.
 const MAX_NB_FRAMES: usize = 100;
 
 /// Prints the current backtrace.
-pub fn print(w: &mut dyn Write, format: PrintFormat) -> io::Result<()> {
+pub fn print(w: &mut dyn Write, format: PrintFmt) -> io::Result<()> {
     static LOCK: Mutex = Mutex::new();
 
     // There are issues currently linking libbacktrace into tests, and in
@@ -39,26 +36,66 @@ pub fn print(w: &mut dyn Write, format: PrintFormat) -> io::Result<()> {
     }
 }
 
-fn _print(w: &mut dyn Write, format: PrintFormat) -> io::Result<()> {
-    writeln!(w, "stack backtrace:")?;
+fn _print(w: &mut dyn Write, format: PrintFmt) -> io::Result<()> {
+    struct DisplayBacktrace {
+        format: PrintFmt,
+    }
+    impl fmt::Display for DisplayBacktrace {
+        fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+            _print_fmt(fmt, self.format)
+        }
+    }
+    write!(w, "{}", DisplayBacktrace { format })
+}
 
-    let mut printer = Printer::new(format, w);
+fn _print_fmt(fmt: &mut fmt::Formatter<'_>, print_fmt: PrintFmt) -> fmt::Result {
+    let mut print_path = move |fmt: &mut fmt::Formatter<'_>, bows: BytesOrWideString<'_>| {
+        output_filename(fmt, bows, print_fmt)
+    };
+    let mut bt_fmt = BacktraceFmt::new(fmt, print_fmt, &mut print_path);
+    bt_fmt.add_context()?;
+    let mut skipped = false;
     unsafe {
+        let mut idx = 0;
+        let mut res = Ok(());
         backtrace::trace_unsynchronized(|frame| {
+            if print_fmt == PrintFmt::Short && idx > MAX_NB_FRAMES {
+                skipped = true;
+                return false;
+            }
+
             let mut hit = false;
+            let mut stop = false;
             backtrace::resolve_frame_unsynchronized(frame, |symbol| {
                 hit = true;
-                printer.output(frame, Some(symbol));
+                if print_fmt == PrintFmt::Short {
+                    if let Some(sym) = symbol.name().and_then(|s| s.as_str()) {
+                        if sym.contains("__rust_begin_short_backtrace") {
+                            skipped = true;
+                            stop = true;
+                            return;
+                        }
+                    }
+                }
+
+                res = bt_fmt.frame().symbol(frame, symbol);
             });
+            if stop {
+                return false;
+            }
             if !hit {
-                printer.output(frame, None);
+                res = bt_fmt.frame().print_raw(frame.ip(), None, None, None);
             }
-            !printer.done
+
+            idx += 1;
+            res.is_ok()
         });
+        res?;
     }
-    if printer.skipped {
+    bt_fmt.finish()?;
+    if skipped {
         writeln!(
-            w,
+            fmt,
             "note: Some details are omitted, \
              run with `RUST_BACKTRACE=full` for a verbose backtrace."
         )?;
@@ -77,33 +114,24 @@ where
     f()
 }
 
-/// Controls how the backtrace should be formatted.
-#[derive(Debug, Copy, Clone, Eq, PartialEq)]
-pub enum PrintFormat {
-    /// Show only relevant data from the backtrace.
-    Short = 2,
-    /// Show all the frames with absolute path for files.
-    Full = 3,
-}
-
 // For now logging is turned off by default, and this function checks to see
 // whether the magical environment variable is present to see if it's turned on.
-pub fn log_enabled() -> Option<PrintFormat> {
+pub fn log_enabled() -> Option<PrintFmt> {
     static ENABLED: atomic::AtomicIsize = atomic::AtomicIsize::new(0);
     match ENABLED.load(Ordering::SeqCst) {
         0 => {}
         1 => return None,
-        2 => return Some(PrintFormat::Short),
-        _ => return Some(PrintFormat::Full),
+        2 => return Some(PrintFmt::Short),
+        _ => return Some(PrintFmt::Full),
     }
 
     let val = env::var_os("RUST_BACKTRACE").and_then(|x| {
         if &x == "0" {
             None
         } else if &x == "full" {
-            Some(PrintFormat::Full)
+            Some(PrintFmt::Full)
         } else {
-            Some(PrintFormat::Short)
+            Some(PrintFmt::Short)
         }
     });
     ENABLED.store(
@@ -116,130 +144,45 @@ pub fn log_enabled() -> Option<PrintFormat> {
     val
 }
 
-struct Printer<'a, 'b> {
-    format: PrintFormat,
-    done: bool,
-    skipped: bool,
-    idx: usize,
-    out: &'a mut (dyn Write + 'b),
-}
-
-impl<'a, 'b> Printer<'a, 'b> {
-    fn new(format: PrintFormat, out: &'a mut (dyn Write + 'b)) -> Printer<'a, 'b> {
-        Printer { format, done: false, skipped: false, idx: 0, out }
-    }
-
-    /// Prints the symbol of the backtrace frame.
-    ///
-    /// These output functions should now be used everywhere to ensure consistency.
-    /// You may want to also use `output_fileline`.
-    fn output(&mut self, frame: &Frame, symbol: Option<&Symbol>) {
-        if self.idx > MAX_NB_FRAMES {
-            self.done = true;
-            self.skipped = true;
-            return;
-        }
-        if self._output(frame, symbol).is_err() {
-            self.done = true;
-        }
-        self.idx += 1;
-    }
-
-    fn _output(&mut self, frame: &Frame, symbol: Option<&Symbol>) -> io::Result<()> {
-        if self.format == PrintFormat::Short {
-            if let Some(sym) = symbol.and_then(|s| s.name()).and_then(|s| s.as_str()) {
-                if sym.contains("__rust_begin_short_backtrace") {
-                    self.skipped = true;
-                    self.done = true;
-                    return Ok(());
-                }
-            }
-
-            // Remove the `17: 0x0 - <unknown>` line.
-            if self.format == PrintFormat::Short && frame.ip() == ptr::null_mut() {
-                self.skipped = true;
-                return Ok(());
-            }
-        }
-
-        match self.format {
-            PrintFormat::Full => {
-                write!(self.out, "  {:2}: {:2$?} - ", self.idx, frame.ip(), HEX_WIDTH)?
-            }
-            PrintFormat::Short => write!(self.out, "  {:2}: ", self.idx)?,
-        }
-
-        match symbol.and_then(|s| s.name()) {
-            Some(symbol) => {
-                match self.format {
-                    PrintFormat::Full => write!(self.out, "{}", symbol)?,
-                    // Strip the trailing hash if short mode.
-                    PrintFormat::Short => write!(self.out, "{:#}", symbol)?,
-                }
-            }
-            None => self.out.write_all(b"<unknown>")?,
+/// Prints the filename of the backtrace frame.
+///
+/// See also `output`.
+fn output_filename(
+    fmt: &mut fmt::Formatter<'_>,
+    bows: BytesOrWideString<'_>,
+    print_fmt: PrintFmt,
+) -> fmt::Result {
+    #[cfg(windows)]
+    let path_buf;
+    let file = match bows {
+        #[cfg(unix)]
+        BytesOrWideString::Bytes(bytes) => {
+            use crate::os::unix::prelude::*;
+            Path::new(crate::ffi::OsStr::from_bytes(bytes))
         }
-        self.out.write_all(b"\n")?;
-        if let Some(sym) = symbol {
-            self.output_fileline(sym)?;
+        #[cfg(not(unix))]
+        BytesOrWideString::Bytes(bytes) => {
+            Path::new(crate::str::from_utf8(bytes).unwrap_or("<unknown>"))
         }
-        Ok(())
-    }
-
-    /// Prints the filename and line number of the backtrace frame.
-    ///
-    /// See also `output`.
-    fn output_fileline(&mut self, symbol: &Symbol) -> io::Result<()> {
         #[cfg(windows)]
-        let path_buf;
-        let file = match symbol.filename_raw() {
-            #[cfg(unix)]
-            Some(BytesOrWideString::Bytes(bytes)) => {
-                use crate::os::unix::prelude::*;
-                Path::new(crate::ffi::OsStr::from_bytes(bytes))
-            }
-            #[cfg(not(unix))]
-            Some(BytesOrWideString::Bytes(bytes)) => {
-                Path::new(crate::str::from_utf8(bytes).unwrap_or("<unknown>"))
-            }
-            #[cfg(windows)]
-            Some(BytesOrWideString::Wide(wide)) => {
-                use crate::os::windows::prelude::*;
-                path_buf = crate::ffi::OsString::from_wide(wide);
-                Path::new(&path_buf)
-            }
-            #[cfg(not(windows))]
-            Some(BytesOrWideString::Wide(_wide)) => {
-                Path::new("<unknown>")
-            }
-            None => return Ok(()),
-        };
-        let line = match symbol.lineno() {
-            Some(line) => line,
-            None => return Ok(()),
-        };
-        // prior line: "  ##: {:2$} - func"
-        self.out.write_all(b"")?;
-        match self.format {
-            PrintFormat::Full => write!(self.out, "           {:1$}", "", HEX_WIDTH)?,
-            PrintFormat::Short => write!(self.out, "           ")?,
+        BytesOrWideString::Wide(wide) => {
+            use crate::os::windows::prelude::*;
+            path_buf = crate::ffi::OsString::from_wide(wide);
+            Path::new(&path_buf)
         }
-
-        let mut already_printed = false;
-        if self.format == PrintFormat::Short && file.is_absolute() {
-            if let Ok(cwd) = env::current_dir() {
-                if let Ok(stripped) = file.strip_prefix(&cwd) {
-                    if let Some(s) = stripped.to_str() {
-                        write!(self.out, "  at .{}{}:{}", path::MAIN_SEPARATOR, s, line)?;
-                        already_printed = true;
-                    }
+        #[cfg(not(windows))]
+        BytesOrWideString::Wide(_wide) => {
+            Path::new("<unknown>")
+        }
+    };
+    if print_fmt == PrintFmt::Short && file.is_absolute() {
+        if let Ok(cwd) = env::current_dir() {
+            if let Ok(stripped) = file.strip_prefix(&cwd) {
+                if let Some(s) = stripped.to_str() {
+                    return write!(fmt, ".{}{}", path::MAIN_SEPARATOR, s);
                 }
             }
         }
-        if !already_printed {
-            write!(self.out, "  at {}:{}", file.display(), line)?;
-        }
-
-        self.out.write_all(b"\n")
     }
+    fmt::Display::fmt(&file.display(), fmt)
 }