fix: allow single sol file remappings (#295)

ref foundry-rs/foundry#6706
tested and confirm solves
foundry-rs/foundry#8499 too
- do not add trailing `/` to remappings if single .sol file remapped -
foundry-rs/foundry#6706 (comment)
- if `stripped_import` is empty then do not join when resolving library
import as will append `/` -
foundry-rs/foundry#6706 (comment)
- fix display so `forge remappings` properly display remappings
`@ens/utils/BytesUtils.sol=src/BytesUtils.sol`

Author: grandizzy

crates/artifacts/solc/src/remappings/mod.rs

@@ -138,8 +138,11 @@ impl fmt::Display for Remapping {
             }
             s.push(':');
         }
-        let name =
-            if !self.name.ends_with('/') { format!("{}/", self.name) } else { self.name.clone() };
+        let name = if needs_trailing_slash(&self.name) {
+            format!("{}/", self.name)
+        } else {
+            self.name.clone()
+        };
         s.push_str(&{
             #[cfg(target_os = "windows")]
             {
@@ -153,7 +156,7 @@ impl fmt::Display for Remapping {
             }
         });
 
-        if !s.ends_with('/') {
+        if needs_trailing_slash(&s) {
             s.push('/');
         }
         f.write_str(&s)
@@ -241,7 +244,7 @@ impl fmt::Display for RelativeRemapping {
             }
         });
 
-        if !s.ends_with('/') {
+        if needs_trailing_slash(&s) {
             s.push('/');
         }
         f.write_str(&s)
@@ -252,10 +255,10 @@ impl From<RelativeRemapping> for Remapping {
     fn from(r: RelativeRemapping) -> Self {
         let RelativeRemapping { context, mut name, path } = r;
         let mut path = path.relative().display().to_string();
-        if !path.ends_with('/') {
+        if needs_trailing_slash(&path) {
             path.push('/');
         }
-        if !name.ends_with('/') {
+        if needs_trailing_slash(&name) {
             name.push('/');
         }
         Self { context, name, path }
@@ -341,6 +344,15 @@ impl<'de> Deserialize<'de> for RelativeRemapping {
     }
 }
 
+/// Helper to determine if name or path of a remapping needs trailing slash.
+/// Returns false if it already ends with a slash or if remapping is a solidity file.
+/// Used to preserve name and path of single file remapping, see
+/// <https://github.com/foundry-rs/foundry/issues/6706>
+/// <https://github.com/foundry-rs/foundry/issues/8499>
+fn needs_trailing_slash(name_or_path: &str) -> bool {
+    !name_or_path.ends_with('/') && !name_or_path.ends_with(".sol")
+}
+
 #[cfg(test)]
 mod tests {
     pub use super::*;
@@ -423,4 +435,21 @@ mod tests {
         );
         assert_eq!(remapping.to_string(), "oz/=a/b/c/d/".to_string());
     }
+
+    // <https://github.com/foundry-rs/foundry/issues/6706#issuecomment-3141270852>
+    #[test]
+    fn can_preserve_single_sol_file_remapping() {
+        let remapping = "@my-lib/B.sol=lib/my-lib/B.sol";
+        let remapping = Remapping::from_str(remapping).unwrap();
+
+        assert_eq!(
+            remapping,
+            Remapping {
+                context: None,
+                name: "@my-lib/B.sol".to_string(),
+                path: "lib/my-lib/B.sol".to_string()
+            }
+        );
+        assert_eq!(remapping.to_string(), "@my-lib/B.sol=lib/my-lib/B.sol".to_string());
+    }
 }

crates/compilers/src/config.rs

@@ -524,7 +524,12 @@ impl<L> ProjectPathsConfig<L> {
             })
             .find_map(|r| {
                 import.strip_prefix(&r.name).ok().map(|stripped_import| {
-                    let lib_path = Path::new(&r.path).join(stripped_import);
+                    let lib_path =
+                        if stripped_import.as_os_str().is_empty() && r.path.ends_with(".sol") {
+                            r.path.clone().into()
+                        } else {
+                            Path::new(&r.path).join(stripped_import)
+                        };
 
                     // we handle the edge case where the path of a remapping ends with "contracts"
                     // (`<name>/=.../contracts`) and the stripped import also starts with
@@ -1196,4 +1201,39 @@ mod tests {
             dependency.join("A.sol")
         );
     }
+
+    #[test]
+    fn can_resolve_single_file_mapped_import() {
+        let dir = tempfile::tempdir().unwrap();
+        let mut config = ProjectPathsConfig::builder().root(dir.path()).build::<()>().unwrap();
+        config.create_all().unwrap();
+
+        fs::write(
+            config.sources.join("A.sol"),
+            r#"pragma solidity ^0.8.0; import "@my-lib/B.sol"; contract A is B {}"#,
+        )
+        .unwrap();
+
+        let dependency = config.root.join("my-lib");
+        fs::create_dir(&dependency).unwrap();
+        fs::write(dependency.join("B.sol"), r"pragma solidity ^0.8.0; contract B {}").unwrap();
+
+        config.remappings.push(Remapping {
+            context: None,
+            name: "@my-lib/B.sol".into(),
+            path: "my-lib/B.sol".into(),
+        });
+
+        // Test that single file import / remapping resolves to file.
+        assert!(config
+            .resolve_import_and_include_paths(
+                &config.sources,
+                Path::new("@my-lib/B.sol"),
+                &mut Default::default(),
+            )
+            .unwrap()
+            .to_str()
+            .unwrap()
+            .ends_with("my-lib/B.sol"));
+    }
 }