fix(solc): purge obsolete cached artifacts

ethers-solc/src/cache.rs

@@ -294,7 +294,7 @@ impl SolFilesCache {
         I: IntoIterator<Item = (&'a Path, V)>,
         V: IntoIterator<Item = &'a Version>,
     {
-        let mut files: HashMap<_, _> = files.into_iter().map(|(p, v)| (p, v)).collect();
+        let mut files: HashMap<_, _> = files.into_iter().collect();
 
         self.files.retain(|file, entry| {
             if entry.artifacts.is_empty() {
@@ -474,7 +474,9 @@ impl CacheEntry {
         }
     }
 
-    /// Retains only those artifacts that match the provided version.
+    /// Retains only those artifacts that match the provided versions.
+    ///
+    /// Removes an artifact entry if none of its versions is included in the `versions` set.
     pub fn retain_versions<'a, I>(&mut self, versions: I)
     where
         I: IntoIterator<Item = &'a Version>,
@@ -874,35 +876,54 @@ impl<'a, T: ArtifactOutput> ArtifactsCache<'a, T> {
                 // keep only those files that were previously filtered (not dirty, reused)
                 cache.retain(filtered.iter().map(|(p, (_, v))| (p.as_path(), v)));
 
-                // add the artifacts to the cache entries, this way we can keep a mapping from
-                // solidity file to its artifacts
+                // add the written artifacts to the cache entries, this way we can keep a mapping
+                // from solidity file to its artifacts
                 // this step is necessary because the concrete artifacts are only known after solc
                 // was invoked and received as output, before that we merely know the file and
                 // the versions, so we add the artifacts on a file by file basis
-                for (file, artifacts) in written_artifacts.as_ref() {
+                for (file, written_artifacts) in written_artifacts.as_ref() {
                     let file_path = Path::new(&file);
-                    if let Some((entry, versions)) = dirty_source_files.get_mut(file_path) {
-                        entry.insert_artifacts(artifacts.iter().map(|(name, artifacts)| {
-                            let artifacts = artifacts
-                                .iter()
-                                .filter(|artifact| versions.contains(&artifact.version))
-                                .collect::<Vec<_>>();
-                            (name, artifacts)
-                        }));
+                    if let Some((cache_entry, versions)) = dirty_source_files.get_mut(file_path) {
+                        cache_entry.insert_artifacts(written_artifacts.iter().map(
+                            |(name, artifacts)| {
+                                let artifacts = artifacts
+                                    .iter()
+                                    .filter(|artifact| versions.contains(&artifact.version))
+                                    .collect::<Vec<_>>();
+                                (name, artifacts)
+                            },
+                        ));
                     }
 
                     // cached artifacts that were overwritten also need to be removed from the
                     // `cached_artifacts` set
                     if let Some((f, mut cached)) = cached_artifacts.0.remove_entry(file) {
-                        cached.retain(|name, files| {
-                            if let Some(written_files) = artifacts.get(name) {
-                                files.retain(|f| {
-                                    written_files.iter().all(|other| other.version != f.version)
+                        tracing::trace!("checking {} for obsolete cached artifact entries", file);
+                        cached.retain(|name, cached_artifacts| {
+                            if let Some(written_files) = written_artifacts.get(name) {
+                                // written artifact clashes with a cached artifact, so we need to decide whether to keep or to remove the cached
+                                cached_artifacts.retain(|f| {
+                                    // we only keep those artifacts that don't conflict with written artifacts and which version was a compiler target
+                                    let retain = written_files
+                                        .iter()
+                                        .all(|other| other.version != f.version) && filtered.get(
+                                        &PathBuf::from(file)).map(|(_, versions)| {
+                                            versions.contains(&f.version)
+                                        }).unwrap_or_default();
+                                    if !retain {
+                                        tracing::trace!(
+                                            "purging obsolete cached artifact for contract {} and version {}",
+                                            name,
+                                            f.version
+                                        );
+                                    }
+                                    retain
                                 });
-                                return !files.is_empty()
+                                return !cached_artifacts.is_empty()
                             }
                             false
                         });
+
                         if !cached.is_empty() {
                             cached_artifacts.0.insert(f, cached);
                         }

ethers-solc/src/compile/mod.rs

@@ -269,6 +269,29 @@ impl Solc {
         Ok(Some(Solc::new(solc)))
     }
 
+    /// Returns the path for a [svm](https://github.com/roynalnaruto/svm-rs) installed version.
+    ///
+    /// If the version is not installed yet, it will install it.
+    ///
+    /// # Example
+    /// ```no_run
+    /// # fn main() -> Result<(), Box<dyn std::error::Error>> {
+    ///  use ethers_solc::Solc;
+    /// let solc = Solc::find_or_install_svm_version("0.8.9").unwrap();
+    /// assert_eq!(solc, Solc::new("~/.svm/0.8.9/solc-0.8.9"));
+    /// # Ok(())
+    /// # }
+    /// ```
+    #[cfg(all(not(target_arch = "wasm32"), all(feature = "svm-solc")))]
+    pub fn find_or_install_svm_version(version: impl AsRef<str>) -> Result<Self> {
+        let version = version.as_ref();
+        if let Some(solc) = Solc::find_svm_installed_version(version)? {
+            Ok(solc)
+        } else {
+            Ok(Solc::blocking_install(&version.parse::<Version>()?)?)
+        }
+    }
+
     /// Assuming the `versions` array is sorted, it returns the first element which satisfies
     /// the provided [`VersionReq`]
     pub fn find_matching_installation(

ethers-solc/src/project_util/mod.rs

@@ -9,7 +9,7 @@ use crate::{
     utils,
     utils::tempdir,
     Artifact, ArtifactOutput, Artifacts, ConfigurableArtifacts, ConfigurableContractArtifact,
-    FileFilter, PathStyle, Project, ProjectCompileOutput, ProjectPathsConfig, SolFilesCache,
+    FileFilter, PathStyle, Project, ProjectCompileOutput, ProjectPathsConfig, SolFilesCache, Solc,
     SolcIoError,
 };
 use fs_extra::{dir, file};
@@ -66,6 +66,13 @@ impl<T: ArtifactOutput> TempProject<T> {
         self
     }
 
+    /// Explicitly sets the solc version for the project
+    pub fn set_solc(&mut self, solc: impl AsRef<str>) -> &mut Self {
+        self.inner.solc = Solc::find_or_install_svm_version(solc).unwrap();
+        self.inner.auto_detect = false;
+        self
+    }
+
     pub fn project(&self) -> &Project<T> {
         &self.inner
     }

ethers-solc/tests/project.rs

@@ -1333,7 +1333,7 @@ fn can_compile_model_checker_sample() {
 
 fn remove_solc_if_exists(version: &Version) {
     match Solc::find_svm_installed_version(version.to_string()).unwrap() {
-        Some(_) => svm::remove_version(&version).expect("failed to remove version"),
+        Some(_) => svm::remove_version(version).expect("failed to remove version"),
         None => {}
     };
 }
@@ -1351,7 +1351,7 @@ async fn can_install_solc_and_compile_version() {
 pragma solidity {};
 contract Contract {{ }}
 "#,
-                version.to_string()
+                version
             ),
         )
         .unwrap();
@@ -1380,3 +1380,34 @@ async fn can_install_solc_and_compile_std_json_input_async() {
     assert!(!out.has_error());
     assert!(out.sources.contains_key("lib/ds-test/src/test.sol"));
 }
+
+#[test]
+fn can_purge_obsolete_artifacts() {
+    let mut project = TempProject::<ConfigurableArtifacts>::dapptools().unwrap();
+    project.set_solc("0.8.10");
+    project
+        .add_source(
+            "Contract",
+            r#"
+    pragma solidity >=0.8.10;
+
+   contract Contract {
+        function xyz() public {
+        }
+   }
+   "#,
+        )
+        .unwrap();
+
+    let compiled = project.compile().unwrap();
+    assert!(!compiled.has_compiler_errors());
+    assert!(!compiled.is_unchanged());
+    assert_eq!(compiled.into_artifacts().count(), 1);
+
+    project.set_solc("0.8.13");
+
+    let compiled = project.compile().unwrap();
+    assert!(!compiled.has_compiler_errors());
+    assert!(!compiled.is_unchanged());
+    assert_eq!(compiled.into_artifacts().count(), 1);
+}