Add initial debug fmt for Backtrace #69038
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r? @shepmaster (rust_highfive has picked a reviewer for you, use r? to override) |
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I'm starting with this most basic version of a Debug format that just derives everything and doesn't force any symbol resolution as a starting point for the rest of the PR, I still haven't tested how this looks in practice because compile times but I'm working on getting a unit test that I can use as a playground to render the format pre and post resolution so I can paste that into this issue for review. |
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This is the current format from this PR, lmk what further changes are necessary. As generated by this small snippet #[cfg(test)]
mod tests {
use super::*;
#[test]
fn debug_backtrace_fmt() {
let bt = Backtrace::capture();
eprintln!("uncaptured: {:?}", bt);
let bt = Backtrace::force_capture();
eprintln!("captured: {:?}", bt);
eprintln!("display print: {}", bt);
eprintln!("resolved: {:?}", bt);
unimplemented!();
}
} |
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r? @dtolnay |
dtolnay
requested changes
Feb 10, 2020
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That representation looks extremely verbose to me. I expect that debug-printed backtraces are going to be a thing that humans see somewhat often (unfortunately) from unwrapped or debug printed error objects containing a backtrace. Could you see if you can strip out everything that wouldn't be informative to the reader?
Before:
Backtrace {
inner: Captured(
Mutex {
data: Capture {
actual_start: 2,
resolved: true,
frames: [
BacktraceFrame {
frame: Frame {
ip: 0x55c1fc866e5d,
symbol_address: 0x55c1fc866de0,
},
symbols: [
BacktraceSymbol {
name: Some(
std::backtrace::Backtrace::create,
),
filename: None,
lineno: None,
},
],
},
BacktraceFrame {
frame: Frame {
ip: 0x55c1fc866dd0,
symbol_address: 0x55c1fc866dc0,
},
symbols: [
BacktraceSymbol {
name: Some(
std::backtrace::Backtrace::force_capture,
),
filename: None,
lineno: None,
},
],
},
...
...
...
],
},
},
),
}More reasonable:
Backtrace [
"std::backtrace::Backtrace::create",
"std::backtrace::Backtrace::force_capture",
"core::ops::function::FnOnce::call_once @ /rustc/src/libcore/ops/function.rs:231",
]or list-of-maps style as suggested in #65280:
Backtrace [
{ fn: "std::backtrace::Backtrace::create" },
{ fn: "std::backtrace::Backtrace::force_capture" },
{ fn: "core::ops::function::FnOnce::call_once", file: "/rustc/src/libcore/ops/function.rs", line: 231 },
]
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Sure, but I'm not sure how to handle the fact that a backtrace frame can have multiple symbols. Also, I'd personally prefer the to use How do you feel about this format |
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
The logic within |
yaahc
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Okay, independent of my previous comment, here is the current format @dtolnay with the changes you've requested. Fixing the |
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Current version, this adds some |
dtolnay
requested changes
Feb 11, 2020
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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Okay here is the current version I manually added |
yaahc
commented
Feb 11, 2020
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and here we go again, for possibly the last time she says with great hubris |
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Sigh... Why are these lines being skipped in the display impl ._. investigates Edit: its because of |
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Nice! Almost there I think. Thanks for sticking with this.
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
I believe the display impl prints the hashes for Here's the comparison between the alt and default display impls
They feel equally easy to read to me, so I have no preference, if you want my vote I'm gonna vote for no Edit: One thing I think might be important is how easily the debug impl can be parsed, so if you think that adding |
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Oh I just noticed the resolved / non-opt debug print for Backtrace had hashes, thats definitely wrong, fixing. |
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And now its backwards, because apparently they switched the meanings of alt where they use the alt print for PrintFmt::Short which is selected when alt is false 🙃 Gonna just make an executive decision here and not try to maintain exact compat with old behavior. |
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Final-final-v2-format.jpg |
dtolnay
approved these changes
Feb 11, 2020
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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@bors r+ |
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📌 Commit ec8ee7f has been approved by |
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Dylan-DPC-zz
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Feb 12, 2020
Add initial debug fmt for Backtrace Fixes the first point in rust-lang#65280 related to rust-lang#53487
bors
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Feb 12, 2020
Rollup of 7 pull requests Successful merges: - #67954 (Support new LLVM pass manager) - #68981 ( Account for type params on method without parentheses) - #69002 (miri: improve and simplify overflow detection) - #69038 (Add initial debug fmt for Backtrace) - #69040 (Cleanup SGX entry code) - #69086 (Update compiler-builtins to 0.1.25) - #69095 (Minified theme check) Failed merges: r? @ghost
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Fixes the first point in #65280
related to #53487