fix(solc): only modify files that are required to compile the project (#1050)

ethers-solc/src/project_util/mock.rs

@@ -12,7 +12,7 @@ use rand::{
 };
 use serde::{Deserialize, Serialize};
 use std::{
-    collections::{BTreeSet, HashMap},
+    collections::{BTreeSet, HashMap, HashSet, VecDeque},
     path::{Path, PathBuf},
 };
 
@@ -25,6 +25,13 @@ pub struct MockProjectSkeleton {
     pub libraries: Vec<MockLib>,
 }
 
+impl MockProjectSkeleton {
+    /// Returns a list of file ids the given file id imports.
+    pub fn imported_nodes(&self, from: usize) -> impl Iterator<Item = usize> + '_ {
+        self.files[from].imports.iter().map(|i| i.file_id())
+    }
+}
+
 /// Represents a virtual project
 #[derive(Serialize)]
 pub struct MockProjectGenerator {
@@ -272,11 +279,27 @@ impl MockProjectGenerator {
         }
     }
 
+    /// Returns the file for the given id
+    pub fn get_file(&self, id: usize) -> &MockFile {
+        &self.inner.files[id]
+    }
+
     /// All file ids
     pub fn file_ids(&self) -> impl Iterator<Item = usize> + '_ {
         self.inner.files.iter().map(|f| f.id)
     }
 
+    /// Returns an iterator over all file ids that are source files or imported by source files
+    ///
+    /// In other words, all files that are relevant in order to compile the project's source files.
+    pub fn used_file_ids(&self) -> impl Iterator<Item = usize> + '_ {
+        let mut file_ids = BTreeSet::new();
+        for file in self.internal_file_ids() {
+            file_ids.extend(NodesIter::new(file, &self.inner))
+        }
+        file_ids.into_iter()
+    }
+
     /// All ids of internal files
     pub fn internal_file_ids(&self) -> impl Iterator<Item = usize> + '_ {
         self.inner.files.iter().filter(|f| !f.is_external()).map(|f| f.id)
@@ -469,6 +492,15 @@ pub enum MockImport {
     External(usize, usize),
 }
 
+impl MockImport {
+    pub fn file_id(&self) -> usize {
+        *match self {
+            MockImport::Internal(id) => id,
+            MockImport::External(_, id) => id,
+        }
+    }
+}
+
 /// Container of a mock lib
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct MockLib {
@@ -552,6 +584,33 @@ impl Default for MockProjectSettings {
     }
 }
 
+/// An iterator over a node and its dependencies
+struct NodesIter<'a> {
+    /// stack of nodes
+    stack: VecDeque<usize>,
+    visited: HashSet<usize>,
+    skeleton: &'a MockProjectSkeleton,
+}
+
+impl<'a> NodesIter<'a> {
+    fn new(start: usize, skeleton: &'a MockProjectSkeleton) -> Self {
+        Self { stack: VecDeque::from([start]), visited: HashSet::new(), skeleton }
+    }
+}
+
+impl<'a> Iterator for NodesIter<'a> {
+    type Item = usize;
+    fn next(&mut self) -> Option<Self::Item> {
+        let file = self.stack.pop_front()?;
+
+        if self.visited.insert(file) {
+            // push the file's direct imports to the stack if we haven't visited it already
+            self.stack.extend(self.skeleton.imported_nodes(file));
+        }
+        Some(file)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

ethers-solc/tests/mocked.rs

@@ -3,7 +3,7 @@
 use ethers_solc::{
     error::Result,
     project_util::{
-        mock::{MockProjectGenerator, MockProjectSettings},
+        mock::{MockProjectGenerator, MockProjectSettings, MockProjectSkeleton},
         TempProject,
     },
 };
@@ -85,7 +85,7 @@ fn can_compile_mocked_modified() {
     run_mock(MockProjectSettings::random(), |project, gen| {
         project.ensure_no_errors_recompile_unchanged()?;
         // modify a random file
-        gen.modify_file(gen.file_ids().count() / 2, project.paths(), DEFAULT_VERSION)?;
+        gen.modify_file(gen.used_file_ids().count() / 2, project.paths(), DEFAULT_VERSION)?;
         project.ensure_changed()?;
         project.artifacts_snapshot()?.assert_artifacts_essentials_present();
         Ok(())
@@ -97,7 +97,7 @@ fn can_compile_mocked_modified_all() {
     run_mock(MockProjectSettings::random(), |project, gen| {
         project.ensure_no_errors_recompile_unchanged()?;
         // modify a random file
-        for id in gen.file_ids() {
+        for id in gen.used_file_ids() {
             gen.modify_file(id, project.paths(), DEFAULT_VERSION)?;
             project.ensure_changed()?;
             project.artifacts_snapshot()?.assert_artifacts_essentials_present();
@@ -105,3 +105,27 @@ fn can_compile_mocked_modified_all() {
         Ok(())
     });
 }
+
+// a test useful to manually debug a serialized skeleton
+#[test]
+fn can_compile_skeleton() {
+    let mut project = TempProject::dapptools().unwrap();
+    let s = r#"{"files":[{"id":0,"name":"SourceFile0","imports":[{"External":[0,1]},{"External":[3,4]}],"lib_id":null,"emit_artifacts":true},{"id":1,"name":"SourceFile1","imports":[],"lib_id":0,"emit_artifacts":true},{"id":2,"name":"SourceFile2","imports":[],"lib_id":1,"emit_artifacts":true},{"id":3,"name":"SourceFile3","imports":[],"lib_id":2,"emit_artifacts":true},{"id":4,"name":"SourceFile4","imports":[],"lib_id":3,"emit_artifacts":true}],"libraries":[{"name":"Lib0","id":0,"offset":1,"num_files":1},{"name":"Lib1","id":1,"offset":2,"num_files":1},{"name":"Lib2","id":2,"offset":3,"num_files":1},{"name":"Lib3","id":3,"offset":4,"num_files":1}]}"#;
+    let gen: MockProjectGenerator = serde_json::from_str::<MockProjectSkeleton>(s).unwrap().into();
+    let remappings = gen.remappings_at(project.root());
+    project.paths_mut().remappings.extend(remappings);
+    project.mock(&gen, DEFAULT_VERSION).unwrap();
+
+    // mattsse: helper to show what's being generated
+    // gen.write_to(&ethers_solc::ProjectPathsConfig::dapptools("./skeleton").unwrap(),
+    // DEFAULT_VERSION).unwrap();
+
+    let compiled = project.compile().unwrap();
+    assert!(!compiled.has_compiler_errors());
+    assert!(!compiled.is_unchanged());
+    for id in gen.used_file_ids() {
+        gen.modify_file(id, project.paths(), DEFAULT_VERSION).unwrap();
+        project.ensure_changed().unwrap();
+        project.artifacts_snapshot().unwrap().assert_artifacts_essentials_present();
+    }
+}