Fixes #4141

compiler-core/src/build/package_compiler.rs

@@ -354,7 +354,7 @@ where
         // we overwrite any precompiled Erlang that was included in the Hex
         // package. Otherwise we will build the potentially outdated precompiled
         // version and not the newly compiled version.
-        Erlang::new(&build_dir, &include_dir).render(io, modules)?;
+        Erlang::new(&build_dir, &include_dir).render(io, modules, self.root)?;
 
         if self.compile_beam_bytecode {
             written.extend(modules.iter().map(Module::compiled_erlang_path));

compiler-core/src/codegen.rs

@@ -33,10 +33,11 @@ impl<'a> Erlang<'a> {
         &self,
         writer: Writer,
         modules: &[Module],
+        root: &Utf8Path
     ) -> Result<()> {
         for module in modules {
             let erl_name = module.name.replace("/", "@");
-            self.erlang_module(&writer, module, &erl_name)?;
+            self.erlang_module(&writer, module, &erl_name, root)?;
             self.erlang_record_headers(&writer, module, &erl_name)?;
         }
         Ok(())
@@ -47,11 +48,12 @@ impl<'a> Erlang<'a> {
         writer: &Writer,
         module: &Module,
         erl_name: &str,
+        root: &Utf8Path
     ) -> Result<()> {
         let name = format!("{erl_name}.erl");
         let path = self.build_directory.join(&name);
         let line_numbers = LineNumbers::new(&module.code);
-        let output = erlang::module(&module.ast, &line_numbers);
+        let output = erlang::module(&module.ast, &line_numbers, root);
         tracing::debug!(name = ?name, "Generated Erlang module");
         writer.write(&path, &output?)
     }

compiler-core/src/erlang.rs

@@ -29,6 +29,7 @@ use regex::{Captures, Regex};
 use std::sync::OnceLock;
 use std::{collections::HashMap, ops::Deref, str::FromStr, sync::Arc};
 use vec1::Vec1;
+use camino::Utf8Path;
 
 const INDENT: isize = 4;
 const MAX_COLUMNS: isize = 80;
@@ -150,13 +151,14 @@ pub fn record_definition(name: &str, fields: &[(&str, Arc<Type>)]) -> String {
     .to_pretty_string(MAX_COLUMNS)
 }
 
-pub fn module<'a>(module: &'a TypedModule, line_numbers: &'a LineNumbers) -> Result<String> {
-    Ok(module_document(module, line_numbers)?.to_pretty_string(MAX_COLUMNS))
+pub fn module<'a>(module: &'a TypedModule, line_numbers: &'a LineNumbers, root: &'a Utf8Path) -> Result<String> {
+    Ok(module_document(module, line_numbers, root)?.to_pretty_string(MAX_COLUMNS))
 }
 
 fn module_document<'a>(
     module: &'a TypedModule,
     line_numbers: &'a LineNumbers,
+    root: &'a Utf8Path
 ) -> Result<Document<'a>> {
     let mut exports = vec![];
     let mut type_defs = vec![];
@@ -217,8 +219,15 @@ fn module_document<'a>(
         join(type_defs, lines(2)).append(lines(2))
     };
 
-    let src_path = EcoString::from(module.type_info.src_path.as_str());
-
+    let src_path_full = EcoString::from(module.type_info.src_path.as_str());
+    let root_str = root.as_str();
+    let src_path_relative = root_str
+        .is_empty()
+        .then(|| src_path_full.clone())
+        .unwrap_or_else(|| src_path_full.strip_prefix(root_str)
+                        .map(|relative_path| module.name.clone() + relative_path)
+                        .unwrap_or_else(|| src_path_full.clone()));
+
     let mut needs_function_docs = false;
     let mut statements = Vec::with_capacity(module.definitions.len());
     for definition in module.definitions.iter() {
@@ -227,7 +236,7 @@ fn module_document<'a>(
             &module.name,
             module.type_info.is_internal,
             line_numbers,
-            &src_path,
+            &src_path_relative,
         ) {
             needs_function_docs = needs_function_docs || env.needs_function_docs;
             statements.push(statement_document);

compiler-core/src/erlang/tests.rs

@@ -14,6 +14,7 @@ use crate::{
     uid::UniqueIdGenerator,
     warning::TypeWarningEmitter,
 };
+use camino::Utf8Path;
 
 mod bit_arrays;
 mod case;
@@ -112,10 +113,11 @@ pub fn compile_test_project(src: &str, src_path: &str, dep: Option<(&str, &str,
         extra: parsed.extra,
         dependencies: vec![],
     };
+    let root = Utf8Path::new("/my/mod");
     built_module.attach_doc_and_module_comments();
 
     let line_numbers = LineNumbers::new(src);
-    module(&built_module.ast, &line_numbers).unwrap()
+    module(&built_module.ast, &line_numbers, &root).unwrap()
 }
 
 #[macro_export]