Infrastructure: trace! macro and bug!(), .bug(), .bug_msg() errors

Cargo.toml

@@ -1,12 +1,16 @@
 [package]
 name = "synless"
 version = "0.0.1"
+edition = "2021"
 authors = ["justinpombrio <[email protected]>", "e-matteson <[email protected]>"]
 
-[workspace]
-members = [
-  "forest",
-  "language",
-  "frontends",
-  "editor",
-  "demo"]
+[dependencies]
+generational-arena = "0.2"
+[dependencies.no-nonsense-flamegraphs]
+    version = "0.2.*"
+    git = "https://github.com/justinpombrio/no-nonsense-flamegraphs"
+    optional = true
+
+[features]
+default = []
+profile = ["no-nonsense-flamegraphs"]

src/infra.rs

@@ -0,0 +1,88 @@
+use crate::bug;
+use std::fmt;
+
+#[doc(hidden)]
+#[macro_export]
+/// You can add this to the top of the body of a function to include it in
+/// flamegraphs when `--features profile` is used.
+macro_rules! trace {
+    ($name:expr) => {
+        #[cfg(feature = "profile")]
+        no_nonsense_flamegraphs::span!($name);
+    };
+}
+
+/// Versions of `.unwrap()` and `.expect()` that print a Synless-specific
+/// error message, and format errors with Display instead of Debug.
+pub trait SynlessBug<T>: Sized {
+    /// Like `.unwrap()`, but with a better error message.
+    fn bug(self) -> T;
+    /// Like `.expect()`, but with a better error message.
+    fn bug_msg(self, msg: &str) -> T;
+}
+
+impl<T> SynlessBug<T> for Option<T> {
+    fn bug(self) -> T {
+        match self {
+            Some(val) => val,
+            None => bug!("Tried to unwrap a `None` value"),
+        }
+    }
+
+    fn bug_msg(self, msg: &str) -> T {
+        match self {
+            Some(val) => val,
+            None => bug!("{}", msg),
+        }
+    }
+}
+
+impl<T, E: fmt::Display> SynlessBug<T> for Result<T, E> {
+    fn bug(self) -> T {
+        match self {
+            Ok(ok) => ok,
+            Err(err) => bug!("{}", err),
+        }
+    }
+
+    fn bug_msg(self, msg: &str) -> T {
+        match self {
+            Ok(ok) => ok,
+            Err(err) => bug!("{}\n{}", msg, err),
+        }
+    }
+}
+
+#[track_caller]
+pub(crate) fn format_bug(location: String, message: String) -> String {
+    let mut output = "\n*** Bug in Synless.".to_owned();
+    output
+        .push_str("\n*** Please open an issue at https://github.com/justinpombrio/synless/issues.");
+    output.push_str("\n*** Location:");
+    output.push_str("\n***   ");
+    output.push_str(&location);
+    output.push_str("\n*** Error message:");
+    for line in message.lines() {
+        output.push_str("\n***   ");
+        output.push_str(line);
+    }
+    output.push('\n');
+    output
+}
+
+#[doc(hidden)]
+#[macro_export]
+/// Like `panic!()`, but with a better error message.
+macro_rules! bug {
+    ($message:literal) => {
+        bug!($message,)
+    };
+    ($message:literal, $( $arg:expr ),*) => {
+        panic!("{}",
+            $crate::infra::format_bug(
+                format!("{}:{}:{}", file!(), line!(), column!()),
+                format!($message, $( $arg ),*)
+            )
+        )
+    };
+}

src/main.rs

@@ -1,3 +1,5 @@
+mod infra;
+
 fn main() {
-    unimplemented!();
+    bug!("not yet implemented");
 }