feat: add CLI argument for debugging comptime blocks (#5192)

# Description

## Problem\*

Resolves #5168

## Summary\*



## Additional Context

- Restores `hir_to_ast` pass as `hir_to_display_ast` from
https://github.com/noir-lang/noir/pull/5147/files
+ Only using it for display is much easier than trying to go back and
forth between HIR and the AST

## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

---------

Co-authored-by: Tom French <15848336+TomAFrench@users.noreply.github.com>
Co-authored-by: jfecher <jake@aztecprotocol.com>

compiler/fm/Cargo.toml

@@ -10,6 +10,7 @@ license.workspace = true
 
 [dependencies]
 codespan-reporting.workspace = true
+iter-extended.workspace = true
 serde.workspace = true
 
 [dev-dependencies]

compiler/fm/src/lib.rs

@@ -7,6 +7,7 @@ mod file_map;
 
 pub use file_map::{File, FileId, FileMap, PathString};
 
+use iter_extended::vecmap;
 // Re-export for the lsp
 pub use codespan_reporting::files as codespan_files;
 
@@ -103,6 +104,26 @@ impl FileManager {
     pub fn name_to_id(&self, file_name: PathBuf) -> Option<FileId> {
         self.file_map.get_file_id(&PathString::from_path(file_name))
     }
+
+    /// Find a file by its path suffix, e.g. "src/main.nr" is a suffix of
+    /// "some_dir/package_name/src/main.nr"`
+    pub fn find_by_path_suffix(&self, suffix: &str) -> Result<Option<FileId>, Vec<PathBuf>> {
+        let suffix_path: Vec<_> = Path::new(suffix).components().rev().collect();
+        let results: Vec<_> = self
+            .path_to_id
+            .iter()
+            .filter(|(path, _id)| {
+                path.components().rev().zip(suffix_path.iter()).all(|(x, y)| &x == y)
+            })
+            .collect();
+        if results.is_empty() {
+            Ok(None)
+        } else if results.len() == 1 {
+            Ok(Some(*results[0].1))
+        } else {
+            Err(vecmap(results, |(path, _id)| path.clone()))
+        }
+    }
 }
 
 pub trait NormalizePath {

compiler/noirc_driver/src/lib.rs

@@ -103,6 +103,11 @@ pub struct CompileOptions {
     #[arg(long, hide = true)]
     pub use_legacy: bool,
 
+    /// Enable printing results of comptime evaluation: provide a path suffix
+    /// for the module to debug, e.g. "package_name/src/main.nr"
+    #[arg(long)]
+    pub debug_comptime_in_file: Option<String>,
+
     /// Outputs the paths to any modified artifacts
     #[arg(long, hide = true)]
     pub show_artifact_paths: bool,
@@ -258,12 +263,14 @@ pub fn check_crate(
     deny_warnings: bool,
     disable_macros: bool,
     use_legacy: bool,
+    debug_comptime_in_file: Option<&str>,
 ) -> CompilationResult<()> {
     let macros: &[&dyn MacroProcessor] =
         if disable_macros { &[] } else { &[&aztec_macros::AztecMacro as &dyn MacroProcessor] };
 
     let mut errors = vec![];
-    let diagnostics = CrateDefMap::collect_defs(crate_id, context, use_legacy, macros);
+    let diagnostics =
+        CrateDefMap::collect_defs(crate_id, context, use_legacy, debug_comptime_in_file, macros);
     errors.extend(diagnostics.into_iter().map(|(error, file_id)| {
         let diagnostic = CustomDiagnostic::from(&error);
         diagnostic.in_file(file_id)
@@ -301,6 +308,7 @@ pub fn compile_main(
         options.deny_warnings,
         options.disable_macros,
         options.use_legacy,
+        options.debug_comptime_in_file.as_deref(),
     )?;
 
     let main = context.get_main_function(&crate_id).ok_or_else(|| {
@@ -342,6 +350,7 @@ pub fn compile_contract(
         options.deny_warnings,
         options.disable_macros,
         options.use_legacy,
+        options.debug_comptime_in_file.as_deref(),
     )?;
 
     // TODO: We probably want to error if contracts is empty

compiler/noirc_driver/tests/stdlib_warnings.rs

@@ -25,7 +25,7 @@ fn stdlib_does_not_produce_constant_warnings() -> Result<(), ErrorsAndWarnings>
     let root_crate_id = prepare_crate(&mut context, file_name);
 
     let ((), warnings) =
-        noirc_driver::check_crate(&mut context, root_crate_id, false, false, false)?;
+        noirc_driver::check_crate(&mut context, root_crate_id, false, false, false, None)?;
 
     assert_eq!(warnings, Vec::new(), "stdlib is producing {} warnings", warnings.len());
 

compiler/noirc_errors/src/reporter.rs

@@ -19,6 +19,7 @@ pub enum DiagnosticKind {
     Error,
     Bug,
     Warning,
+    Info,
 }
 
 /// A count of errors that have been already reported to stderr
@@ -37,30 +38,57 @@ impl CustomDiagnostic {
         }
     }
 
-    pub fn simple_error(
+    fn simple_with_kind(
         primary_message: String,
         secondary_message: String,
         secondary_span: Span,
+        kind: DiagnosticKind,
     ) -> CustomDiagnostic {
         CustomDiagnostic {
             message: primary_message,
             secondaries: vec![CustomLabel::new(secondary_message, secondary_span)],
             notes: Vec::new(),
-            kind: DiagnosticKind::Error,
+            kind,
         }
     }
 
+    pub fn simple_error(
+        primary_message: String,
+        secondary_message: String,
+        secondary_span: Span,
+    ) -> CustomDiagnostic {
+        Self::simple_with_kind(
+            primary_message,
+            secondary_message,
+            secondary_span,
+            DiagnosticKind::Error,
+        )
+    }
+
     pub fn simple_warning(
         primary_message: String,
         secondary_message: String,
         secondary_span: Span,
     ) -> CustomDiagnostic {
-        CustomDiagnostic {
-            message: primary_message,
-            secondaries: vec![CustomLabel::new(secondary_message, secondary_span)],
-            notes: Vec::new(),
-            kind: DiagnosticKind::Warning,
-        }
+        Self::simple_with_kind(
+            primary_message,
+            secondary_message,
+            secondary_span,
+            DiagnosticKind::Warning,
+        )
+    }
+
+    pub fn simple_info(
+        primary_message: String,
+        secondary_message: String,
+        secondary_span: Span,
+    ) -> CustomDiagnostic {
+        Self::simple_with_kind(
+            primary_message,
+            secondary_message,
+            secondary_span,
+            DiagnosticKind::Info,
+        )
     }
 
     pub fn simple_bug(
@@ -96,6 +124,10 @@ impl CustomDiagnostic {
         matches!(self.kind, DiagnosticKind::Warning)
     }
 
+    pub fn is_info(&self) -> bool {
+        matches!(self.kind, DiagnosticKind::Info)
+    }
+
     pub fn is_bug(&self) -> bool {
         matches!(self.kind, DiagnosticKind::Bug)
     }
@@ -191,6 +223,7 @@ fn convert_diagnostic(
 ) -> Diagnostic<fm::FileId> {
     let diagnostic = match (cd.kind, deny_warnings) {
         (DiagnosticKind::Warning, false) => Diagnostic::warning(),
+        (DiagnosticKind::Info, _) => Diagnostic::note(),
         (DiagnosticKind::Bug, ..) => Diagnostic::bug(),
         _ => Diagnostic::error(),
     };

compiler/noirc_frontend/src/elaborator/expressions.rs

@@ -9,22 +9,22 @@ use crate::{
         UnresolvedTypeExpression,
     },
     hir::{
-        comptime::{self, Interpreter, InterpreterError},
+        comptime::{self, InterpreterError},
         resolution::{errors::ResolverError, resolver::LambdaContext},
         type_check::TypeCheckError,
     },
     hir_def::{
         expr::{
             HirArrayLiteral, HirBinaryOp, HirBlockExpression, HirCallExpression, HirCastExpression,
-            HirConstructorExpression, HirIfExpression, HirIndexExpression, HirInfixExpression,
-            HirLambda, HirMemberAccess, HirMethodCallExpression, HirMethodReference,
-            HirPrefixExpression,
+            HirConstructorExpression, HirExpression, HirIfExpression, HirIndexExpression,
+            HirInfixExpression, HirLambda, HirMemberAccess, HirMethodCallExpression,
+            HirMethodReference, HirPrefixExpression,
         },
         traits::TraitConstraint,
     },
     macros_api::{
-        BlockExpression, CallExpression, CastExpression, Expression, ExpressionKind, HirExpression,
-        HirLiteral, HirStatement, Ident, IndexExpression, Literal, MemberAccessExpression,
+        BlockExpression, CallExpression, CastExpression, Expression, ExpressionKind, HirLiteral,
+        HirStatement, Ident, IndexExpression, Literal, MemberAccessExpression,
         MethodCallExpression, PrefixExpression,
     },
     node_interner::{DefinitionKind, ExprId, FuncId, ReferenceId},
@@ -674,12 +674,20 @@ impl<'context> Elaborator<'context> {
         // call is not yet solved for.
         self.function_context.push(Default::default());
         let (block, _typ) = self.elaborate_block_expression(block);
-        self.check_and_pop_function_context();
 
-        let mut interpreter =
-            Interpreter::new(self.interner, &mut self.comptime_scopes, self.crate_id);
+        self.check_and_pop_function_context();
+        let mut interpreter_errors = vec![];
+        let mut interpreter = self.setup_interpreter(&mut interpreter_errors);
         let value = interpreter.evaluate_block(block);
-        self.inline_comptime_value(value, span)
+        self.include_interpreter_errors(interpreter_errors);
+        let (id, typ) = self.inline_comptime_value(value, span);
+
+        let location = self.interner.id_location(id);
+        self.debug_comptime(location, |interner| {
+            interner.expression(&id).to_display_ast(interner, location.span).kind
+        });
+
+        (id, typ)
     }
 
     pub(super) fn inline_comptime_value(
@@ -750,9 +758,9 @@ impl<'context> Elaborator<'context> {
             }
         };
 
-        let mut interpreter =
-            Interpreter::new(self.interner, &mut self.comptime_scopes, self.crate_id);
-
+        let file = self.file;
+        let mut interpreter_errors = vec![];
+        let mut interpreter = self.setup_interpreter(&mut interpreter_errors);
         let mut comptime_args = Vec::new();
         let mut errors = Vec::new();
 
@@ -762,17 +770,19 @@ impl<'context> Elaborator<'context> {
                     let location = interpreter.interner.expr_location(&argument);
                     comptime_args.push((arg, location));
                 }
-                Err(error) => errors.push((error.into(), self.file)),
+                Err(error) => errors.push((error.into(), file)),
             }
         }
 
+        let bindings = interpreter.interner.get_instantiation_bindings(func).clone();
+        let result = interpreter.call_function(function, comptime_args, bindings, location);
+        self.include_interpreter_errors(interpreter_errors);
+
         if !errors.is_empty() {
             self.errors.append(&mut errors);
             return None;
         }
 
-        let bindings = interpreter.interner.get_instantiation_bindings(func).clone();
-        let result = interpreter.call_function(function, comptime_args, bindings, location);
         let (expr_id, typ) = self.inline_comptime_value(result, location.span);
         Some((self.interner.expression(&expr_id), typ))
     }