1 files changed, 86 insertions, 0 deletions
diff --git a/src/panic.rs b/src/panic.rs
new file mode 100644
index 0000000..ad98cac
--- /dev/null
+++ b/src/panic.rs
@@ -0,0 +1,86 @@
+use backtrace::Backtrace;
+use thiserror::Error;
+
+use crate::{self as miette, Context, Diagnostic, Result};
+
+/// Tells miette to render panics using its rendering engine.
+pub fn set_panic_hook() {
+    std::panic::set_hook(Box::new(move |info| {
+        let mut message = "Something went wrong".to_string();
+        let payload = info.payload();
+        if let Some(msg) = payload.downcast_ref::<&str>() {
+            message = msg.to_string();
+        }
+        if let Some(msg) = payload.downcast_ref::<String>() {
+            message = msg.clone();
+        }
+        let mut report: Result<()> = Err(Panic(message).into());
+        if let Some(loc) = info.location() {
+            report = report
+                .with_context(|| format!("at {}:{}:{}", loc.file(), loc.line(), loc.column()));
+        }
+        if let Err(err) = report.with_context(|| "Main thread panicked.".to_string()) {
+            eprintln!("Error: {:?}", err);
+        }
+    }));
+}
+
+#[derive(Debug, Error, Diagnostic)]
+#[error("{0}{}", Panic::backtrace())]
+#[diagnostic(help("set the `RUST_BACKTRACE=1` environment variable to display a backtrace."))]
+struct Panic(String);
+
+impl Panic {
+    fn backtrace() -> String {
+        use std::fmt::Write;
+        if let Ok(var) = std::env::var("RUST_BACKTRACE") {
+            if !var.is_empty() && var != "0" {
+                const HEX_WIDTH: usize = std::mem::size_of::<usize>() + 2;
+                // Padding for next lines after frame's address
+                const NEXT_SYMBOL_PADDING: usize = HEX_WIDTH + 6;
+                let mut backtrace = String::new();
+                let trace = Backtrace::new();
+                let frames = backtrace_ext::short_frames_strict(&trace).enumerate();
+                for (idx, (frame, sub_frames)) in frames {
+                    let ip = frame.ip();
+                    let _ = write!(backtrace, "\n{:4}: {:2$?}", idx, ip, HEX_WIDTH);
+
+                    let symbols = frame.symbols();
+                    if symbols.is_empty() {
+                        let _ = write!(backtrace, " - <unresolved>");
+                        continue;
+                    }
+
+                    for (idx, symbol) in symbols[sub_frames].iter().enumerate() {
+                        // Print symbols from this address,
+                        // if there are several addresses
+                        // we need to put it on next line
+                        if idx != 0 {
+                            let _ = write!(backtrace, "\n{:1$}", "", NEXT_SYMBOL_PADDING);
+                        }
+
+                        if let Some(name) = symbol.name() {
+                            let _ = write!(backtrace, " - {}", name);
+                        } else {
+                            let _ = write!(backtrace, " - <unknown>");
+                        }
+
+                        // See if there is debug information with file name and line
+                        if let (Some(file), Some(line)) = (symbol.filename(), symbol.lineno()) {
+                            let _ = write!(
+                                backtrace,
+                                "\n{:3$}at {}:{}",
+                                "",
+                                file.display(),
+                                line,
+                                NEXT_SYMBOL_PADDING
+                            );
+                        }
+                    }
+                }
+                return backtrace;
+            }
+        }
+        "".into()
+    }
+}