[red-knot] Unresolved imports lint rule

crates/red_knot/src/cancellation.rs

@@ -12,7 +12,7 @@ impl CancellationTokenSource {
         }
     }
 
-    #[tracing::instrument(level = "trace")]
+    #[tracing::instrument(level = "trace", skip_all)]
     pub fn cancel(&self) {
         let (cancelled, condvar) = &*self.signal;
 

crates/red_knot/src/db.rs

@@ -2,7 +2,7 @@ use std::path::Path;
 use std::sync::Arc;
 
 use crate::files::FileId;
-use crate::lint::{Diagnostics, LintSyntaxStorage};
+use crate::lint::{Diagnostics, LintSemanticStorage, LintSyntaxStorage};
 use crate::module::{Module, ModuleData, ModuleName, ModuleResolver, ModuleSearchPath};
 use crate::parse::{Parsed, ParsedStorage};
 use crate::source::{Source, SourceStorage};
@@ -32,13 +32,15 @@ pub trait SemanticDb: SourceDb {
 
     fn symbol_table(&self, file_id: FileId) -> Arc<SymbolTable>;
 
+    fn infer_symbol_type(&self, file_id: FileId, symbol_id: SymbolId) -> Type;
+
+    fn lint_semantic(&self, file_id: FileId) -> Diagnostics;
+
     // mutations
 
     fn add_module(&mut self, path: &Path) -> Option<(Module, Vec<Arc<ModuleData>>)>;
 
     fn set_module_search_paths(&mut self, paths: Vec<ModuleSearchPath>);
-
-    fn infer_symbol_type(&mut self, file_id: FileId, symbol_id: SymbolId) -> Type;
 }
 
 pub trait Db: SemanticDb {}
@@ -55,6 +57,7 @@ pub struct SemanticJar {
     pub module_resolver: ModuleResolver,
     pub symbol_tables: SymbolTablesStorage,
     pub type_store: TypeStore,
+    pub lint_semantic: LintSemanticStorage,
 }
 
 /// Gives access to a specific jar in the database.
@@ -79,9 +82,12 @@ pub trait HasJar<T> {
 
 #[cfg(test)]
 pub(crate) mod tests {
+    use std::path::Path;
+    use std::sync::Arc;
+
     use crate::db::{HasJar, SourceDb, SourceJar};
     use crate::files::{FileId, Files};
-    use crate::lint::{lint_syntax, Diagnostics};
+    use crate::lint::{lint_semantic, lint_syntax, Diagnostics};
     use crate::module::{
         add_module, file_to_module, path_to_module, resolve_module, set_module_search_paths,
         Module, ModuleData, ModuleName, ModuleSearchPath,
@@ -90,8 +96,6 @@ pub(crate) mod tests {
     use crate::source::{source_text, Source};
     use crate::symbols::{symbol_table, SymbolId, SymbolTable};
     use crate::types::{infer_symbol_type, Type};
-    use std::path::Path;
-    use std::sync::Arc;
 
     use super::{SemanticDb, SemanticJar};
 
@@ -163,16 +167,20 @@ pub(crate) mod tests {
             symbol_table(self, file_id)
         }
 
+        fn infer_symbol_type(&self, file_id: FileId, symbol_id: SymbolId) -> Type {
+            infer_symbol_type(self, file_id, symbol_id)
+        }
+
+        fn lint_semantic(&self, file_id: FileId) -> Diagnostics {
+            lint_semantic(self, file_id)
+        }
+
         fn add_module(&mut self, path: &Path) -> Option<(Module, Vec<Arc<ModuleData>>)> {
             add_module(self, path)
         }
 
         fn set_module_search_paths(&mut self, paths: Vec<ModuleSearchPath>) {
             set_module_search_paths(self, paths);
         }
-
-        fn infer_symbol_type(&mut self, file_id: FileId, symbol_id: SymbolId) -> Type {
-            infer_symbol_type(self, file_id, symbol_id)
-        }
     }
 }

crates/red_knot/src/lib.rs

@@ -1,3 +1,4 @@
+use std::fmt::Formatter;
 use std::hash::BuildHasherDefault;
 use std::ops::Deref;
 use std::path::{Path, PathBuf};
@@ -100,3 +101,9 @@ where
         Self(value.into())
     }
 }
+
+impl std::fmt::Display for Name {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.write_str(self.as_str())
+    }
+}

crates/red_knot/src/lint.rs

@@ -1,12 +1,17 @@
+use std::cell::RefCell;
 use std::ops::{Deref, DerefMut};
 use std::sync::Arc;
 
 use ruff_python_ast::visitor::Visitor;
-use ruff_python_ast::StringLiteral;
+use ruff_python_ast::{ModModule, StringLiteral};
 
 use crate::cache::KeyValueCache;
-use crate::db::{HasJar, SourceDb, SourceJar};
+use crate::db::{HasJar, SemanticDb, SemanticJar, SourceDb, SourceJar};
 use crate::files::FileId;
+use crate::parse::Parsed;
+use crate::source::Source;
+use crate::symbols::{Definition, SymbolId, SymbolTable};
+use crate::types::Type;
 
 #[tracing::instrument(level = "debug", skip(db))]
 pub(crate) fn lint_syntax<Db>(db: &Db, file_id: FileId) -> Diagnostics
@@ -40,7 +45,7 @@ where
     })
 }
 
-pub(crate) fn lint_lines(source: &str, diagnostics: &mut Vec<String>) {
+fn lint_lines(source: &str, diagnostics: &mut Vec<String>) {
     for (line_number, line) in source.lines().enumerate() {
         if line.len() < 88 {
             continue;
@@ -57,6 +62,108 @@ pub(crate) fn lint_lines(source: &str, diagnostics: &mut Vec<String>) {
     }
 }
 
+#[tracing::instrument(level = "debug", skip(db))]
+pub(crate) fn lint_semantic<Db>(db: &Db, file_id: FileId) -> Diagnostics
+where
+    Db: SemanticDb + HasJar<SemanticJar>,
+{
+    let storage = &db.jar().lint_semantic;
+
+    storage.get(&file_id, |file_id| {
+        let source = db.source(*file_id);
+        let parsed = db.parse(*file_id);
+        let symbols = db.symbol_table(*file_id);
+
+        let context = SemanticLintContext {
+            file_id: *file_id,
+            source,
+            parsed,
+            symbols,
+            db,
+            diagnostics: RefCell::new(Vec::new()),
+        };
+
+        lint_unresolved_imports(&context);
+
+        Diagnostics::from(context.diagnostics.take())
+    })
+}
+
+fn lint_unresolved_imports(context: &SemanticLintContext) {
+    for (symbol, definition) in context.symbols().all_definitions() {
+        match definition {
+            Definition::Import(import) => {
+                let ty = context.eval_symbol(symbol);
+
+                if ty.is_unknown() {
+                    context.push_diagnostic(format!("Unresolved module {}", import.module));
+                }
+            }
+            Definition::ImportFrom(import) => {
+                let ty = context.eval_symbol(symbol);
+
+                if ty.is_unknown() {
+                    let message = if let Some(module) = import.module() {
+                        format!(
+                            "Unresolved relative import '{}' from '{}{module}'",
+                            import.name(),
+                            ".".repeat(import.level() as usize)
+                        )
+                    } else {
+                        format!(
+                            "Unresolved import '{}' from {}",
+                            import.name(),
+                            ".".repeat(import.level() as usize)
+                        )
+                    };
+
+                    context.push_diagnostic(message);
+                }
+            }
+            _ => {}
+        }
+    }
+}
+
+pub struct SemanticLintContext<'a> {
+    file_id: FileId,
+    source: Source,
+    parsed: Parsed,
+    symbols: Arc<SymbolTable>,
+    db: &'a dyn SemanticDb,
+    diagnostics: RefCell<Vec<String>>,
+}
+
+impl<'a> SemanticLintContext<'a> {
+    pub fn source_text(&self) -> &str {
+        self.source.text()
+    }
+
+    pub fn file_id(&self) -> FileId {
+        self.file_id
+    }
+
+    pub fn ast(&self) -> &ModModule {
+        self.parsed.ast()
+    }
+
+    pub fn symbols(&self) -> &SymbolTable {
+        &self.symbols
+    }
+
+    pub fn eval_symbol(&self, symbol_id: SymbolId) -> Type {
+        self.db.infer_symbol_type(self.file_id, symbol_id)
+    }
+
+    pub fn push_diagnostic(&self, diagnostic: String) {
+        self.diagnostics.borrow_mut().push(diagnostic);
+    }
+
+    pub fn extend_diagnostics(&mut self, diagnostics: impl IntoIterator<Item = String>) {
+        self.diagnostics.get_mut().extend(diagnostics);
+    }
+}
+
 #[derive(Debug)]
 struct SyntaxLintVisitor<'a> {
     diagnostics: Vec<String>,
@@ -123,3 +230,20 @@ impl DerefMut for LintSyntaxStorage {
         &mut self.0
     }
 }
+
+#[derive(Default, Debug)]
+pub struct LintSemanticStorage(KeyValueCache<FileId, Diagnostics>);
+
+impl Deref for LintSemanticStorage {
+    type Target = KeyValueCache<FileId, Diagnostics>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for LintSemanticStorage {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}

crates/red_knot/src/program/check.rs

@@ -1,11 +1,13 @@
+use std::num::NonZeroUsize;
+
+use rayon::max_num_threads;
+use rustc_hash::FxHashSet;
+
 use crate::cancellation::CancellationToken;
 use crate::db::{SemanticDb, SourceDb};
 use crate::files::FileId;
 use crate::lint::Diagnostics;
 use crate::program::Program;
-use rayon::max_num_threads;
-use rustc_hash::FxHashSet;
-use std::num::NonZeroUsize;
 
 impl Program {
     /// Checks all open files in the workspace and its dependencies.
@@ -71,6 +73,7 @@ impl Program {
 
         if self.workspace().is_file_open(file) {
             diagnostics.extend_from_slice(&self.lint_syntax(file));
+            diagnostics.extend_from_slice(&self.lint_semantic(file));
         }
 
         Ok(Diagnostics::from(diagnostics))

crates/red_knot/src/program/mod.rs

@@ -5,7 +5,7 @@ use std::sync::Arc;
 
 use crate::db::{Db, HasJar, SemanticDb, SemanticJar, SourceDb, SourceJar};
 use crate::files::{FileId, Files};
-use crate::lint::{lint_syntax, Diagnostics, LintSyntaxStorage};
+use crate::lint::{lint_semantic, lint_syntax, Diagnostics, LintSyntaxStorage};
 use crate::module::{
     add_module, file_to_module, path_to_module, resolve_module, set_module_search_paths, Module,
     ModuleData, ModuleName, ModuleResolver, ModuleSearchPath,
@@ -36,6 +36,7 @@ impl Program {
                 module_resolver: ModuleResolver::new(module_search_paths),
                 symbol_tables: SymbolTablesStorage::default(),
                 type_store: TypeStore::default(),
+                lint_semantic: LintSemanticStorage::default(),
             },
             files: Files::default(),
             workspace,
@@ -56,6 +57,7 @@ impl Program {
             self.source.lint_syntax.remove(&change.id);
             // TODO: remove all dependent modules as well
             self.semantic.type_store.remove_module(change.id);
+            self.semantic.lint_semantic.remove(&change.id);
         }
     }
 
@@ -111,19 +113,22 @@ impl SemanticDb for Program {
         symbol_table(self, file_id)
     }
 
-    // Mutations
+    fn infer_symbol_type(&self, file_id: FileId, symbol_id: SymbolId) -> Type {
+        infer_symbol_type(self, file_id, symbol_id)
+    }
+
+    fn lint_semantic(&self, file_id: FileId) -> Diagnostics {
+        lint_semantic(self, file_id)
+    }
 
+    // Mutations
     fn add_module(&mut self, path: &Path) -> Option<(Module, Vec<Arc<ModuleData>>)> {
         add_module(self, path)
     }
 
     fn set_module_search_paths(&mut self, paths: Vec<ModuleSearchPath>) {
         set_module_search_paths(self, paths);
     }
-
-    fn infer_symbol_type(&mut self, file_id: FileId, symbol_id: SymbolId) -> Type {
-        infer_symbol_type(self, file_id, symbol_id)
-    }
 }
 
 impl Db for Program {}