fix(tvix/eval): format nested compiler errors in fancy output r/5092

Instead of just printing the number of errors (useless!) actually emit
separate diagnostics for each nested error.

Change-Id: I97b53c3276c906af5def89077b5b6ba6ec108b37
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6933
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

1 files changed, 22 insertions, 10 deletions

diff --git a/tvix/eval/src/errors.rs b/tvix/eval/src/errors.rs
index 3986640beb..543ae7d41e 100644
--- a/tvix/eval/src/errors.rs
+++ b/tvix/eval/src/errors.rs
@@ -320,15 +320,10 @@ to a missing value in the attribute set(s) included via `with`."#,
                 )
             }
 
-            ErrorKind::ImportCompilerError { errors, path } => {
-                // TODO: chain display of these errors, though this is
-                // probably not the right place for that (should
-                // branch into a more elaborate diagnostic() call
-                // below).
-                write!(
+            ErrorKind::ImportCompilerError { path, .. } => {
+                writeln!(
                     f,
-                    "{} errors occured while importing '{}'",
-                    errors.len(),
+                    "compiler errors occured while importing '{}'",
                     path.to_string_lossy()
                 )
             }
@@ -572,7 +567,7 @@ fn spans_for_parse_errors(file: &File, errors: &[rnix::parser::ParseError]) -> V
 impl Error {
     pub fn fancy_format_str(&self, source: &SourceCode) -> String {
         let mut out = vec![];
-        Emitter::vec(&mut out, Some(&*source.codemap())).emit(&[self.diagnostic(source)]);
+        Emitter::vec(&mut out, Some(&*source.codemap())).emit(&self.diagnostics(source));
         String::from_utf8_lossy(&out).to_string()
     }
 
@@ -580,7 +575,7 @@ impl Error {
     /// it to stderr.
     pub fn fancy_format_stderr(&self, source: &SourceCode) {
         Emitter::stderr(ColorConfig::Auto, Some(&*source.codemap()))
-            .emit(&[self.diagnostic(source)]);
+            .emit(&self.diagnostics(source));
     }
 
     /// Create the optional span label displayed as an annotation on
@@ -713,6 +708,7 @@ impl Error {
         }
     }
 
+    /// Create the primary diagnostic for a given error.
     fn diagnostic(&self, source: &SourceCode) -> Diagnostic {
         Diagnostic {
             level: Level::Error,
@@ -721,4 +717,20 @@ impl Error {
             code: Some(self.code().into()),
         }
     }
+
+    /// Return the primary diagnostic and all further associated diagnostics (if
+    /// any) of an error.
+    fn diagnostics(&self, source: &SourceCode) -> Vec<Diagnostic> {
+        match &self.kind {
+            ErrorKind::ThunkForce(err) => err.diagnostics(source),
+
+            ErrorKind::ImportCompilerError { errors, .. } => {
+                let mut out = vec![self.diagnostic(source)];
+                out.extend(errors.iter().map(|e| e.diagnostic(source)));
+                out
+            }
+
+            _ => vec![self.diagnostic(source)],
+        }
+    }
 }