feat: add Linter

Cargo.lock

@@ -112,6 +112,7 @@ dependencies = [
  "els",
  "erg_common",
  "erg_compiler",
+ "erg_linter",
  "erg_parser",
 ]
 
@@ -136,6 +137,15 @@ dependencies = [
  "pyo3",
 ]
 
+[[package]]
+name = "erg_linter"
+version = "0.6.33"
+dependencies = [
+ "erg_common",
+ "erg_compiler",
+ "erg_parser",
+]
+
 [[package]]
 name = "erg_parser"
 version = "0.6.33"

Cargo.toml

@@ -15,6 +15,7 @@ homepage.workspace = true
 members = [
     "crates/erg_common",
     "crates/erg_compiler",
+    "crates/erg_linter/",
     "crates/erg_parser",
     "crates/els",
     "crates/erg_proc_macros/",
@@ -30,45 +31,50 @@ homepage = "https://erg-lang.org/"
 
 [features]
 # when "debug" feature is turned on, that of the following crates will also be turned on.
-debug = ["erg_common/debug", "erg_parser/debug", "erg_compiler/debug"] # "els/debug"
+debug = ["erg_common/debug", "erg_parser/debug", "erg_compiler/debug", "erg_linter/debug"] # "els/debug"
 backtrace = ["erg_common/backtrace", "els/backtrace"]
 japanese = [
     "erg_common/japanese",
     "erg_parser/japanese",
     "erg_compiler/japanese",
     "els/japanese",
+    "erg_linter/japanese",
 ]
 simplified_chinese = [
     "erg_common/simplified_chinese",
     "erg_parser/simplified_chinese",
     "erg_compiler/simplified_chinese",
     "els/simplified_chinese",
+    "erg_linter/simplified_chinese",
 ]
 traditional_chinese = [
     "erg_common/traditional_chinese",
     "erg_parser/traditional_chinese",
     "erg_compiler/traditional_chinese",
     "els/traditional_chinese",
+    "erg_linter/traditional_chinese",
 ]
-unicode = ["erg_common/unicode", "erg_parser/unicode", "erg_compiler/unicode", "els/unicode"]
-pretty = ["erg_common/pretty", "erg_parser/pretty", "erg_compiler/pretty", "els/pretty"]
+unicode = ["erg_common/unicode", "erg_parser/unicode", "erg_compiler/unicode", "els/unicode", "erg_linter/unicode"]
+pretty = ["erg_common/pretty", "erg_parser/pretty", "erg_compiler/pretty", "els/pretty", "erg_linter/pretty"]
 large_thread = [
     "erg_common/large_thread",
     "erg_parser/large_thread",
     "erg_compiler/large_thread",
     "els/large_thread",
+    "erg_linter/large_thread",
 ]
 py_compat = ["erg_compiler/py_compat", "els/py_compat"]
 gal = ["erg_common/gal", "erg_compiler/gal"]
 els = ["erg_common/els", "erg_compiler/els", "dep:els"]
 full-repl = ["erg_common/full-repl"]
 full = ["els", "full-repl", "unicode", "pretty"]
-experimental = ["erg_common/experimental", "erg_parser/experimental", "erg_compiler/experimental"]
+experimental = ["erg_common/experimental", "erg_parser/experimental", "erg_compiler/experimental", "erg_linter/experimental"]
 
 [workspace.dependencies]
 erg_common = { version = "0.6.33", path = "./crates/erg_common" }
 erg_parser = { version = "0.6.33", path = "./crates/erg_parser" }
 erg_compiler = { version = "0.6.33", path = "./crates/erg_compiler" }
+erg_linter = { version = "0.6.33", path = "./crates/erg_linter" }
 els = { version = "0.1.45", path = "./crates/els" }
 erg_proc_macros = { version = "0.6.33", path = "./crates/erg_proc_macros" }
 pyo3 = { version = "0.20", features = ["extension-module"] }
@@ -77,6 +83,7 @@ pyo3 = { version = "0.20", features = ["extension-module"] }
 erg_common = { workspace = true }
 erg_parser = { workspace = true }
 erg_compiler = { workspace = true }
+erg_linter = { workspace = true }
 els = { workspace = true, optional = true }
 
 [build-dependencies]

crates/els/diagnostics.rs

@@ -11,7 +11,6 @@ use erg_common::dict::Dict;
 use erg_common::pathutil::{project_entry_file_of, project_root_dir_of};
 use erg_common::spawn::{safe_yield, spawn_new_thread};
 use erg_common::style::*;
-use erg_common::traits::Stream;
 use erg_common::{fn_name, lsp_log};
 use erg_compiler::artifact::BuildRunnable;
 use erg_compiler::build_package::CheckStatus;

crates/erg_common/config.rs

@@ -31,6 +31,7 @@ pub enum ErgMode {
     Transpile,
     Execute,
     LanguageServer,
+    Lint,
     Read,
     Pack,
 }
@@ -48,6 +49,7 @@ impl TryFrom<&str> for ErgMode {
             "trans" | "transpile" | "transpiler" => Ok(Self::Transpile),
             "run" | "execute" => Ok(Self::Execute),
             "server" | "language-server" => Ok(Self::LanguageServer),
+            "lint" | "linter" => Ok(Self::Lint),
             "byteread" | "read" | "reader" | "dis" => Ok(Self::Read),
             "pack" | "package" => Ok(Self::Pack),
             _ => Err(()),
@@ -67,6 +69,7 @@ impl From<ErgMode> for &str {
             ErgMode::Transpile => "transpile",
             ErgMode::Execute => "execute",
             ErgMode::LanguageServer => "language-server",
+            ErgMode::Lint => "lint",
             ErgMode::Read => "read",
             ErgMode::Pack => "pack",
         }

crates/erg_compiler/error/mod.rs

@@ -646,6 +646,14 @@ impl CompileErrors {
     pub fn take(&mut self) -> Self {
         self.flush()
     }
+
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
 }
 
 pub type SingleCompileResult<T> = Result<T, CompileError>;

crates/erg_linter/Cargo.toml

@@ -0,0 +1,49 @@
+[package]
+name = "erg_linter"
+description = "the Erg linter"
+documentation = "http://docs.rs/erg_linter"
+version.workspace = true
+authors.workspace = true
+license.workspace = true
+edition.workspace = true
+repository.workspace = true
+homepage.workspace = true
+
+[features]
+debug = ["erg_common/debug", "erg_parser/debug", "erg_compiler/debug"]
+backtrace = ["erg_common/backtrace"]
+japanese = [
+    "erg_common/japanese",
+    "erg_parser/japanese",
+    "erg_compiler/japanese",
+]
+simplified_chinese = [
+    "erg_common/simplified_chinese",
+    "erg_parser/simplified_chinese",
+    "erg_compiler/simplified_chinese",
+]
+traditional_chinese = [
+    "erg_common/traditional_chinese",
+    "erg_parser/traditional_chinese",
+    "erg_compiler/traditional_chinese",
+]
+unicode = ["erg_common/unicode", "erg_parser/unicode", "erg_compiler/unicode"]
+pretty = ["erg_common/pretty", "erg_parser/pretty", "erg_compiler/pretty"]
+large_thread = [
+    "erg_common/large_thread",
+    "erg_parser/large_thread",
+    "erg_compiler/large_thread",
+]
+py_compat = ["erg_compiler/py_compat"]
+gal = ["erg_common/gal", "erg_compiler/gal"]
+full-repl = ["erg_common/full-repl"]
+full = ["full-repl", "unicode", "pretty"]
+experimental = ["erg_common/experimental", "erg_parser/experimental", "erg_compiler/experimental"]
+
+[dependencies]
+erg_common = { workspace = true }
+erg_parser = { workspace = true }
+erg_compiler ={ workspace = true }
+
+[lib]
+path = "lib.rs"

crates/erg_linter/README.md

@@ -8,12 +8,16 @@ The following codes are warned.
 
 * Unreachable codes
 * Wildcard import
-* Unused variables
 * Shadowing of built-in variables
-* Unused objects that are not `NoneLike`
 * Procedures without side-effects
 * Variables that can be defined as constants
 * Unnecessary `.clone`
 * Mutable objects that do not change
 * Hardcoded well-known constants (e.g. `3.14`)
 * Defining a subroutine with too many parameters
+* Defining a class with too many fields
+
+### These are warned by the compiler
+
+* Unused variables
+* Unused objects that are not `NoneLike`

crates/erg_linter/lib.rs

@@ -1,3 +1,4 @@
 mod lint;
+mod warn;
 
 pub use lint::Linter;

crates/erg_linter/lint.rs

@@ -1,19 +1,323 @@
-use erg_common::Str;
+use erg_common::config::ErgConfig;
+use erg_common::error::ErrorKind;
+use erg_common::error::{ErrorDisplay, MultiErrorDisplay};
+use erg_common::io::Input;
+use erg_common::log;
+use erg_common::traits::{BlockKind, ExitStatus, Locational, New, Runnable, Stream};
 
-use crate::error::CompileWarnings;
-use crate::hir::HIR;
+use erg_compiler::artifact::{Buildable, ErrorArtifact};
+use erg_compiler::build_package::PackageBuilder;
+use erg_compiler::error::{CompileError, CompileErrors, CompileWarnings};
+use erg_compiler::hir::{Accessor, Array, Def, Dict, Expr, Set, Signature, Tuple};
+use erg_compiler::module::SharedCompilerResource;
 
-#[derive(Debug, Default)]
+use erg_parser::ParserRunner;
+
+use crate::warn::too_many_params;
+
+#[derive(Debug)]
 pub struct Linter {
-    _used: Vec<Str>,
+    pub cfg: ErgConfig,
+    builder: PackageBuilder,
+    warns: CompileWarnings,
+}
+
+impl Default for Linter {
+    fn default() -> Self {
+        Self::new(ErgConfig::default())
+    }
+}
+
+impl New for Linter {
+    fn new(cfg: ErgConfig) -> Self {
+        let shared = SharedCompilerResource::new(cfg.copy());
+        Self {
+            builder: PackageBuilder::new(cfg.copy(), shared),
+            cfg,
+            warns: CompileWarnings::empty(),
+        }
+    }
+}
+
+impl Runnable for Linter {
+    type Err = CompileError;
+    type Errs = CompileErrors;
+    const NAME: &'static str = "Erg linter";
+
+    #[inline]
+    fn cfg(&self) -> &ErgConfig {
+        &self.cfg
+    }
+    #[inline]
+    fn cfg_mut(&mut self) -> &mut ErgConfig {
+        &mut self.cfg
+    }
+
+    #[inline]
+    fn finish(&mut self) {}
+
+    fn initialize(&mut self) {
+        self.builder.initialize();
+        self.warns.clear();
+    }
+
+    fn clear(&mut self) {
+        self.builder.clear();
+        self.warns.clear();
+    }
+
+    fn set_input(&mut self, input: erg_common::io::Input) {
+        self.cfg.input = input;
+        self.builder.set_input(self.cfg.input.clone());
+    }
+
+    fn exec(&mut self) -> Result<ExitStatus, Self::Errs> {
+        let warns = self.lint_module().map_err(|eart| {
+            eart.warns.write_all_stderr();
+            eart.errors
+        })?;
+        warns.write_all_stderr();
+        Ok(ExitStatus::compile_passed(warns.len()))
+    }
+
+    fn eval(&mut self, src: String) -> Result<String, CompileErrors> {
+        let warns = self.lint(src).map_err(|eart| {
+            eart.warns.write_all_stderr();
+            eart.errors
+        })?;
+        warns.write_all_stderr();
+        Ok("OK".to_string())
+    }
+
+    fn expect_block(&self, src: &str) -> BlockKind {
+        let mut parser = ParserRunner::new(self.cfg().clone());
+        match parser.eval(src.to_string()) {
+            Err(errs) => {
+                let kind = errs
+                    .iter()
+                    .filter(|e| e.core().kind == ErrorKind::ExpectNextLine)
+                    .map(|e| {
+                        let msg = e.core().sub_messages.last().unwrap();
+                        // ExpectNextLine error must have msg otherwise it's a bug
+                        msg.get_msg().first().unwrap().to_owned()
+                    })
+                    .next();
+                if let Some(kind) = kind {
+                    return BlockKind::from(kind.as_str());
+                }
+                if errs
+                    .iter()
+                    .any(|err| err.core.main_message.contains("\"\"\""))
+                {
+                    return BlockKind::MultiLineStr;
+                }
+                BlockKind::Error
+            }
+            Ok(_) => {
+                if src.contains("Class") {
+                    return BlockKind::ClassDef;
+                }
+                BlockKind::None
+            }
+        }
+    }
 }
 
 impl Linter {
-    pub fn new() -> Self {
-        Self { _used: Vec::new() }
+    pub fn new(cfg: ErgConfig) -> Self {
+        New::new(cfg)
     }
 
-    pub fn lint(&mut self, _hir: &HIR) -> CompileWarnings {
-        CompileWarnings::empty()
+    fn caused_by(&self) -> String {
+        self.builder.get_context().unwrap().context.caused_by()
+    }
+
+    fn input(&self) -> Input {
+        self.builder.input().clone()
+    }
+
+    pub fn lint_module(&mut self) -> Result<CompileWarnings, ErrorArtifact> {
+        let src = self.input().read();
+        self.lint(src)
+    }
+
+    pub fn lint(&mut self, src: String) -> Result<CompileWarnings, ErrorArtifact> {
+        log!(info "Start linting");
+        let art = self.builder.build(src, "exec")?;
+        self.warns.extend(art.warns);
+        for chunk in art.object.module.iter() {
+            self.lint_too_many_params(chunk);
+        }
+        log!(info "Finished linting");
+        Ok(self.warns.take())
+    }
+
+    fn lint_too_many_params(&mut self, chunk: &Expr) {
+        match chunk {
+            Expr::Def(Def {
+                sig: Signature::Subr(subr),
+                body,
+            }) => {
+                if subr.params.len() >= 8 {
+                    self.warns.push(too_many_params(
+                        self.input(),
+                        self.caused_by(),
+                        subr.params.loc(),
+                    ));
+                }
+                for chunk in body.block.iter() {
+                    self.lint_too_many_params(chunk);
+                }
+            }
+            _ => self.check_recursively(&Self::lint_too_many_params, chunk),
+        }
+    }
+
+    /* ↓ Helper methods ↓ */
+    fn check_recursively(&mut self, lint_fn: &impl Fn(&mut Linter, &Expr), expr: &Expr) {
+        match expr {
+            Expr::Literal(_) => {}
+            Expr::Record(record) => {
+                for attr in record.attrs.iter() {
+                    for chunk in attr.body.block.iter() {
+                        lint_fn(self, chunk);
+                    }
+                    if let Signature::Subr(subr) = &attr.sig {
+                        for param in subr.params.defaults.iter() {
+                            lint_fn(self, &param.default_val);
+                        }
+                    }
+                }
+            }
+            Expr::Array(array) => match array {
+                Array::Normal(arr) => {
+                    for elem in arr.elems.pos_args.iter() {
+                        lint_fn(self, &elem.expr);
+                    }
+                }
+                Array::WithLength(arr) => {
+                    lint_fn(self, &arr.elem);
+                    if let Some(len) = &arr.len {
+                        lint_fn(self, len);
+                    }
+                }
+                Array::Comprehension(arr) => {
+                    lint_fn(self, &arr.elem);
+                    lint_fn(self, &arr.guard);
+                }
+            },
+            Expr::Tuple(tuple) => match tuple {
+                Tuple::Normal(tup) => {
+                    for elem in tup.elems.pos_args.iter() {
+                        lint_fn(self, &elem.expr);
+                    }
+                }
+            },
+            Expr::Set(set) => match set {
+                Set::Normal(set) => {
+                    for elem in set.elems.pos_args.iter() {
+                        lint_fn(self, &elem.expr);
+                    }
+                }
+                Set::WithLength(set) => {
+                    lint_fn(self, &set.elem);
+                    lint_fn(self, &set.len);
+                }
+            },
+            Expr::Dict(dict) => match dict {
+                Dict::Normal(dic) => {
+                    for kv in dic.kvs.iter() {
+                        lint_fn(self, &kv.key);
+                        lint_fn(self, &kv.value);
+                    }
+                }
+                _ => {
+                    log!("Dict comprehension not implemented");
+                }
+            },
+            Expr::BinOp(binop) => {
+                lint_fn(self, &binop.lhs);
+                lint_fn(self, &binop.rhs);
+            }
+            Expr::UnaryOp(unaryop) => {
+                lint_fn(self, &unaryop.expr);
+            }
+            Expr::Call(call) => {
+                lint_fn(self, &call.obj);
+                for arg in call.args.iter() {
+                    lint_fn(self, arg);
+                }
+            }
+            Expr::Def(def) => {
+                for chunk in def.body.block.iter() {
+                    lint_fn(self, chunk);
+                }
+                if let Signature::Subr(subr) = &def.sig {
+                    for param in subr.params.defaults.iter() {
+                        lint_fn(self, &param.default_val);
+                    }
+                }
+            }
+            Expr::ClassDef(class_def) => {
+                if let Signature::Subr(subr) = &class_def.sig {
+                    for param in subr.params.defaults.iter() {
+                        lint_fn(self, &param.default_val);
+                    }
+                }
+                for methods in class_def.methods_list.iter() {
+                    for method in methods.defs.iter() {
+                        lint_fn(self, method);
+                    }
+                }
+            }
+            Expr::PatchDef(class_def) => {
+                if let Signature::Subr(subr) = &class_def.sig {
+                    for param in subr.params.defaults.iter() {
+                        lint_fn(self, &param.default_val);
+                    }
+                }
+                for method in class_def.methods.iter() {
+                    lint_fn(self, method);
+                }
+            }
+            Expr::ReDef(redef) => {
+                self.check_acc_recursively(lint_fn, &redef.attr);
+                for chunk in redef.block.iter() {
+                    lint_fn(self, chunk);
+                }
+            }
+            Expr::Lambda(lambda) => {
+                for chunk in lambda.body.iter() {
+                    lint_fn(self, chunk);
+                }
+                for param in lambda.params.defaults.iter() {
+                    lint_fn(self, &param.default_val);
+                }
+            }
+            Expr::TypeAsc(tasc) => {
+                lint_fn(self, &tasc.expr);
+            }
+            Expr::Accessor(acc) => {
+                self.check_acc_recursively(lint_fn, acc);
+            }
+            Expr::Compound(exprs) => {
+                for chunk in exprs.iter() {
+                    lint_fn(self, chunk);
+                }
+            }
+            Expr::Dummy(exprs) => {
+                for chunk in exprs.iter() {
+                    lint_fn(self, chunk);
+                }
+            }
+            _ => {}
+        }
+    }
+
+    fn check_acc_recursively(&mut self, lint_fn: impl Fn(&mut Linter, &Expr), acc: &Accessor) {
+        match acc {
+            Accessor::Attr(attr) => lint_fn(self, &attr.obj),
+            Accessor::Ident(_) => {}
+        }
     }
 }

crates/erg_linter/warn.rs

@@ -0,0 +1,17 @@
+use erg_common::error::{ErrorCore, ErrorKind, Location};
+use erg_common::io::Input;
+use erg_compiler::error::CompileWarning;
+
+pub(crate) fn too_many_params(input: Input, caused_by: String, loc: Location) -> CompileWarning {
+    CompileWarning::new(
+        ErrorCore::new(
+            vec![],
+            "too many parameters".to_string(),
+            0,
+            ErrorKind::Warning,
+            loc,
+        ),
+        input,
+        caused_by,
+    )
+}

src/dummy.rs

@@ -8,7 +8,7 @@ use std::time::Duration;
 use erg_common::config::ErgConfig;
 use erg_common::error::{ErrorDisplay, ErrorKind, MultiErrorDisplay};
 use erg_common::python_util::spawn_py;
-use erg_common::traits::{BlockKind, ExitStatus, New, Runnable, Stream};
+use erg_common::traits::{BlockKind, ExitStatus, New, Runnable};
 
 use erg_compiler::hir::Expr;
 use erg_compiler::ty::HasType;

src/main.rs

@@ -7,6 +7,7 @@ use erg_common::spawn::exec_new_thread;
 use erg_common::traits::{ExitStatus, Runnable};
 
 use erg_compiler::build_package::{PackageBuilder, PackageTypeChecker};
+use erg_linter::Linter;
 use erg_parser::lex::LexerRunner;
 use erg_parser::ParserRunner;
 
@@ -29,6 +30,7 @@ fn run() {
         Execute => DummyVM::run(cfg),
         Read => Deserializer::run(cfg),
         Pack => PackageManagerRunner::run(cfg),
+        Lint => Linter::run(cfg),
         LanguageServer => {
             #[cfg(feature = "els")]
             {

tests/common.rs

@@ -9,7 +9,7 @@ use erg_common::python_util::PythonVersion;
 use erg_common::spawn::exec_new_thread;
 use erg_common::style::remove_style;
 use erg_common::style::{colors::DEBUG_MAIN, RESET};
-use erg_common::traits::{ExitStatus, Runnable, Stream};
+use erg_common::traits::{ExitStatus, Runnable};
 
 use erg_compiler::error::CompileErrors;
 use erg_compiler::Compiler;