Create a lint authoring helper (generates matching code)

.gitignore

@@ -31,6 +31,4 @@ util/gh-pages/lints.json
 
 helper.txt
 
-*.stdout
-
 .vscode

clippy_lints/src/lib.rs

@@ -222,6 +222,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
     reg.register_early_lint_pass(box utils::internal_lints::Clippy);
     reg.register_late_lint_pass(box utils::internal_lints::LintWithoutLintPass::default());
     reg.register_late_lint_pass(box utils::inspector::Pass);
+    reg.register_late_lint_pass(box utils::author::Pass);
     reg.register_late_lint_pass(box types::TypePass);
     reg.register_late_lint_pass(box booleans::NonminimalBool);
     reg.register_late_lint_pass(box eq_op::EqOp);

clippy_lints/src/utils/author.rs

@@ -0,0 +1,470 @@
+//! A group of attributes that can be attached to Rust code in order
+//! to generate a clippy lint detecting said code automatically.
+
+#![allow(print_stdout, use_debug)]
+
+use rustc::lint::*;
+use rustc::hir;
+use rustc::hir::{Expr, QPath, Expr_};
+use rustc::hir::intravisit::{Visitor, NestedVisitorMap};
+use syntax::ast::{Attribute, NodeId, LitKind, DUMMY_NODE_ID, self};
+use syntax::codemap::Span;
+use std::collections::HashMap;
+
+/// **What it does:** Generates clippy code that detects the offending pattern
+///
+/// **Example:**
+/// ```rust
+/// fn foo() {
+///     // detect the following pattern
+///     #[clippy(author)]
+///     if x == 42 {
+///         // but ignore everything from here on
+///         #![clippy(author = "ignore")]
+///     }
+/// }
+/// ```
+///
+/// prints
+///
+/// ```
+/// if_let_chain!{[
+///     let Expr_::ExprIf(ref cond, ref then, None) = item.node,
+///     let Expr_::ExprBinary(BinOp::Eq, ref left, ref right) = cond.node,
+///     let Expr_::ExprPath(ref path) = left.node,
+///     let Expr_::ExprLit(ref lit) = right.node,
+///     let LitKind::Int(42, _) = lit.node,
+/// ], {
+///     // report your lint here
+/// }}
+/// ```
+declare_lint! {
+    pub LINT_AUTHOR,
+    Warn,
+    "helper for writing lints"
+}
+
+pub struct Pass;
+
+impl LintPass for Pass {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(LINT_AUTHOR)
+    }
+}
+
+fn prelude() {
+    println!("if_let_chain!{{[");
+}
+
+fn done() {
+    println!("], {{");
+    println!("    // report your lint here");
+    println!("}}}}");
+}
+
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
+    fn check_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
+        if !has_attr(&item.attrs) {
+            return;
+        }
+        prelude();
+        PrintVisitor::new("item").visit_item(item);
+        done();
+    }
+
+    fn check_impl_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ImplItem) {
+        if !has_attr(&item.attrs) {
+            return;
+        }
+        prelude();
+        PrintVisitor::new("item").visit_impl_item(item);
+        done();
+    }
+
+    fn check_trait_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
+        if !has_attr(&item.attrs) {
+            return;
+        }
+        prelude();
+        PrintVisitor::new("item").visit_trait_item(item);
+        done();
+    }
+
+    fn check_variant(&mut self, _cx: &LateContext<'a, 'tcx>, var: &'tcx hir::Variant, generics: &hir::Generics) {
+        if !has_attr(&var.node.attrs) {
+            return;
+        }
+        prelude();
+        PrintVisitor::new("var").visit_variant(var, generics, DUMMY_NODE_ID);
+        done();
+    }
+
+    fn check_struct_field(&mut self, _cx: &LateContext<'a, 'tcx>, field: &'tcx hir::StructField) {
+        if !has_attr(&field.attrs) {
+            return;
+        }
+        prelude();
+        PrintVisitor::new("field").visit_struct_field(field);
+        done();
+    }
+
+    fn check_expr(&mut self, _cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
+        if !has_attr(&expr.attrs) {
+            return;
+        }
+        prelude();
+        PrintVisitor::new("expr").visit_expr(expr);
+        done();
+    }
+
+    fn check_arm(&mut self, _cx: &LateContext<'a, 'tcx>, arm: &'tcx hir::Arm) {
+        if !has_attr(&arm.attrs) {
+            return;
+        }
+        prelude();
+        PrintVisitor::new("arm").visit_arm(arm);
+        done();
+    }
+
+    fn check_stmt(&mut self, _cx: &LateContext<'a, 'tcx>, stmt: &'tcx hir::Stmt) {
+        if !has_attr(stmt.node.attrs()) {
+            return;
+        }
+        prelude();
+        PrintVisitor::new("stmt").visit_stmt(stmt);
+        done();
+    }
+
+    fn check_foreign_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ForeignItem) {
+        if !has_attr(&item.attrs) {
+            return;
+        }
+        prelude();
+        PrintVisitor::new("item").visit_foreign_item(item);
+        done();
+    }
+}
+
+impl PrintVisitor {
+    fn new(s: &'static str) -> Self {
+        PrintVisitor {
+            ids: HashMap::new(),
+            current: s.to_owned(),
+        }
+    }
+
+    fn next(&mut self, s: &'static str) -> String {
+        use std::collections::hash_map::Entry::*;
+        match self.ids.entry(s) {
+            // already there: start numbering from `1`
+            Occupied(mut occ) => {
+                let val = occ.get_mut();
+                *val += 1;
+                format!("{}{}", s, *val)
+            },
+            // not there: insert and return name as given
+            Vacant(vac) => {
+                vac.insert(0);
+                s.to_owned()
+            }
+        }
+    }
+}
+
+struct PrintVisitor {
+    /// Fields are the current index that needs to be appended to pattern binding names
+    ids: HashMap<&'static str, usize>,
+    /// the name that needs to be destructured
+    current: String,
+}
+
+impl<'tcx> Visitor<'tcx> for PrintVisitor {
+    fn visit_expr(&mut self, expr: &Expr) {
+        print!("    let Expr_::Expr");
+        let current = format!("{}.node", self.current);
+        match expr.node {
+            Expr_::ExprBox(ref inner) => {
+                let inner_pat = self.next("inner");
+                println!("Box(ref {}) = {},", inner_pat, current);
+                self.current = inner_pat;
+                self.visit_expr(inner);
+            },
+            Expr_::ExprArray(ref elements) => {
+                let elements_pat = self.next("elements");
+                println!("Array(ref {}) = {},", elements_pat, current);
+                println!("    {}.len() == {},", elements_pat, elements.len());
+                for (i, element) in elements.iter().enumerate() {
+                    self.current = format!("{}[{}]", elements_pat, i);
+                    self.visit_expr(element);
+                }
+            },
+            Expr_::ExprCall(ref _func, ref _args) => {
+                println!("Call(ref func, ref args) = {},", current);
+                println!("    // unimplemented: `ExprCall` is not further destructured at the moment");
+            },
+            Expr_::ExprMethodCall(ref _method_name, ref _generics, ref _args) => {
+                println!("MethodCall(ref method_name, ref generics, ref args) = {},", current);
+                println!("    // unimplemented: `ExprMethodCall` is not further destructured at the moment");
+            },
+            Expr_::ExprTup(ref elements) => {
+                let elements_pat = self.next("elements");
+                println!("Tup(ref {}) = {},", elements_pat, current);
+                println!("    {}.len() == {},", elements_pat, elements.len());
+                for (i, element) in elements.iter().enumerate() {
+                    self.current = format!("{}[{}]", elements_pat, i);
+                    self.visit_expr(element);
+                }
+            },
+            Expr_::ExprBinary(ref op, ref left, ref right) => {
+                let op_pat = self.next("op");
+                let left_pat = self.next("left");
+                let right_pat = self.next("right");
+                println!("Binary(ref {}, ref {}, ref {}) = {},", op_pat, left_pat, right_pat, current);
+                println!("    BinOp_::{:?} == {}.node,", op.node, op_pat);
+                self.current = left_pat;
+                self.visit_expr(left);
+                self.current = right_pat;
+                self.visit_expr(right);
+            },
+            Expr_::ExprUnary(ref op, ref inner) => {
+                let inner_pat = self.next("inner");
+                println!("Unary(UnOp::{:?}, ref {}) = {},", op, inner_pat, current);
+                self.current = inner_pat;
+                self.visit_expr(inner);
+            },
+            Expr_::ExprLit(ref lit) => {
+                let lit_pat = self.next("lit");
+                println!("Lit(ref {}) = {},", lit_pat, current);
+                match lit.node {
+                    LitKind::Bool(val) => println!("    let LitKind::Bool({:?}) = {}.node,", val, lit_pat),
+                    LitKind::Char(c) => println!("    let LitKind::Char({:?}) = {}.node,", c, lit_pat),
+                    LitKind::Byte(b) => println!("    let LitKind::Byte({}) = {}.node,", b, lit_pat),
+                    // FIXME: also check int type
+                    LitKind::Int(i, _) => println!("    let LitKind::Int({}, _) = {}.node,", i, lit_pat),
+                    LitKind::Float(..) => println!("    let LitKind::Float(..) = {}.node,", lit_pat),
+                    LitKind::FloatUnsuffixed(_) => println!("    let LitKind::FloatUnsuffixed(_) = {}.node,", lit_pat),
+                    LitKind::ByteStr(ref vec) => {
+                        let vec_pat = self.next("vec");
+                        println!("    let LitKind::ByteStr(ref {}) = {}.node,", vec_pat, lit_pat);
+                        println!("    let [{:?}] = **{},", vec, vec_pat);
+                    },
+                    LitKind::Str(ref text, _) => {
+                        let str_pat = self.next("s");
+                        println!("    let LitKind::Str(ref {}) = {}.node,", str_pat, lit_pat);
+                        println!("    {}.as_str() == {:?}", str_pat, &*text.as_str())
+                    },
+                }
+            }
+            Expr_::ExprCast(ref expr, ref _ty) => {
+                let cast_pat = self.next("expr");
+                println!("Cast(ref {}, _) = {},", cast_pat, current);
+                self.current = cast_pat;
+                self.visit_expr(expr);
+            },
+            Expr_::ExprType(ref expr, ref _ty) => {
+                let cast_pat = self.next("expr");
+                println!("Type(ref {}, _) = {},", cast_pat, current);
+                self.current = cast_pat;
+                self.visit_expr(expr);
+            },
+            Expr_::ExprIf(ref cond, ref then, ref opt_else) => {
+                let cond_pat = self.next("cond");
+                let then_pat = self.next("then");
+                if let Some(ref else_) = *opt_else {
+                    let else_pat = self.next("else_");
+                    println!("If(ref {}, ref {}, Some(ref {})) = {},", cond_pat, then_pat, else_pat, current);
+                    self.current = else_pat;
+                    self.visit_expr(else_);
+                } else {
+                    println!("If(ref {}, ref {}, None) = {},", cond_pat, then_pat, current);
+                }
+                self.current = cond_pat;
+                self.visit_expr(cond);
+                self.current = then_pat;
+                self.visit_expr(then);
+            }
+            Expr_::ExprWhile(ref _cond, ref _body, ref _opt_label) => {
+                println!("While(ref cond, ref body, ref opt_label) = {},", current);
+                println!("    // unimplemented: `ExprWhile` is not further destructured at the moment");
+            },
+            Expr_::ExprLoop(ref _body, ref _opt_label, ref _desuraging) => {
+                println!("Loop(ref body, ref opt_label, ref desugaring) = {},", current);
+                println!("    // unimplemented: `ExprLoop` is not further destructured at the moment");
+            },
+            Expr_::ExprMatch(ref _expr, ref _arms, ref _desugaring) => {
+                println!("Match(ref expr, ref arms, ref desugaring) = {},", current);
+                println!("    // unimplemented: `ExprMatch` is not further destructured at the moment");
+            },
+            Expr_::ExprClosure(ref _capture_clause, ref _func, _, _) => {
+                println!("Closure(ref capture_clause, ref func, _, _) = {},", current);
+                println!("    // unimplemented: `ExprClosure` is not further destructured at the moment");
+            },
+            Expr_::ExprBlock(ref block) => {
+                let block_pat = self.next("block");
+                println!("Block(ref {}) = {},", block_pat, current);
+                self.current = block_pat;
+                self.visit_block(block);
+            },
+            Expr_::ExprAssign(ref target, ref value) => {
+                let target_pat = self.next("target");
+                let value_pat = self.next("value");
+                println!("Assign(ref {}, ref {}) = {},", target_pat, value_pat, current);
+                self.current = target_pat;
+                self.visit_expr(target);
+                self.current = value_pat;
+                self.visit_expr(value);
+            },
+            Expr_::ExprAssignOp(ref op, ref target, ref value) => {
+                let op_pat = self.next("op");
+                let target_pat = self.next("target");
+                let value_pat = self.next("value");
+                println!("AssignOp(ref {}, ref {}, ref {}) = {},", op_pat, target_pat, value_pat, current);
+                println!("    BinOp_::{:?} == {}.node,", op.node, op_pat);
+                self.current = target_pat;
+                self.visit_expr(target);
+                self.current = value_pat;
+                self.visit_expr(value);
+            },
+            Expr_::ExprField(ref object, ref field_name) => {
+                let obj_pat = self.next("object");
+                let field_name_pat = self.next("field_name");
+                println!("Field(ref {}, ref {}) = {},", obj_pat, field_name_pat, current);
+                println!("    {}.node.as_str() == {:?}", field_name_pat, field_name.node.as_str());
+                self.current = obj_pat;
+                self.visit_expr(object);
+            },
+            Expr_::ExprTupField(ref object, ref field_id) => {
+                let obj_pat = self.next("object");
+                let field_id_pat = self.next("field_id");
+                println!("TupField(ref {}, ref {}) = {},", obj_pat, field_id_pat, current);
+                println!("    {}.node == {}", field_id_pat, field_id.node);
+                self.current = obj_pat;
+                self.visit_expr(object);
+            },
+            Expr_::ExprIndex(ref object, ref index) => {
+                let object_pat = self.next("object");
+                let index_pat = self.next("index");
+                println!("Index(ref {}, ref {}) = {},", object_pat, index_pat, current);
+                self.current = object_pat;
+                self.visit_expr(object);
+                self.current = index_pat;
+                self.visit_expr(index);
+            },
+            Expr_::ExprPath(ref path) => {
+                let path_pat = self.next("path");
+                println!("Path(ref {}) = {},", path_pat, current);
+                self.current = path_pat;
+                self.visit_qpath(path, expr.id, expr.span);
+            },
+            Expr_::ExprAddrOf(mutability, ref inner) => {
+                let inner_pat = self.next("inner");
+                println!("AddrOf({:?}, ref {}) = {},", mutability, inner_pat, current);
+                self.current = inner_pat;
+                self.visit_expr(inner);
+            },
+            Expr_::ExprBreak(ref _destination, ref opt_value) => {
+                let destination_pat = self.next("destination");
+                if let Some(ref value) = *opt_value {
+                    let value_pat = self.next("value");
+                    println!("Break(ref {}, Some(ref {})) = {},", destination_pat, value_pat, current);
+                    self.current = value_pat;
+                    self.visit_expr(value);
+                } else {
+                    println!("Break(ref {}, None) = {},", destination_pat, current);
+                }
+                // FIXME: implement label printing
+            },
+            Expr_::ExprAgain(ref _destination) => {
+                let destination_pat = self.next("destination");
+                println!("Again(ref {}) = {},", destination_pat, current);
+                // FIXME: implement label printing
+            },
+            Expr_::ExprRet(ref opt_value) => {
+                if let Some(ref value) = *opt_value {
+                    let value_pat = self.next("value");
+                    println!("Ret(Some(ref {})) = {},", value_pat, current);
+                    self.current = value_pat;
+                    self.visit_expr(value);
+                } else {
+                    println!("Ret(None) = {},", current);
+                }
+            },
+            Expr_::ExprInlineAsm(_, ref _input, ref _output) => {
+                println!("InlineAsm(_, ref input, ref output) = {},", current);
+                println!("    // unimplemented: `ExprInlineAsm` is not further destructured at the moment");
+            },
+            Expr_::ExprStruct(ref path, ref fields, ref opt_base) => {
+                let path_pat = self.next("path");
+                let fields_pat = self.next("fields");
+                if let Some(ref base) = *opt_base {
+                    let base_pat = self.next("base");
+                    println!("Struct(ref {}, ref {}, Some(ref {})) = {},", path_pat, fields_pat, base_pat, current);
+                    self.current = base_pat;
+                    self.visit_expr(base);
+                } else {
+                    println!("Struct(ref {}, ref {}, None) = {},", path_pat, fields_pat, current);
+                }
+                self.current = path_pat;
+                self.visit_qpath(path, expr.id, expr.span);
+                println!("    {}.len() == {},", fields_pat, fields.len());
+                println!("    // unimplemented: field checks");
+            },
+            // FIXME: compute length (needs type info)
+            Expr_::ExprRepeat(ref value, _) => {
+                let value_pat = self.next("value");
+                println!("Repeat(ref {}, _) = {},", value_pat, current);
+                println!("// unimplemented: repeat count check");
+                self.current = value_pat;
+                self.visit_expr(value);
+            },
+        }
+    }
+
+    fn visit_qpath(&mut self, path: &QPath, _: NodeId, _: Span) {
+        print!("    match_path({}, &[", self.current);
+        print_path(path, &mut true);
+        println!("]),");
+    }
+    fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
+        NestedVisitorMap::None
+    }
+}
+
+fn has_attr(attrs: &[Attribute]) -> bool {
+    attrs.iter().any(|attr| {
+        attr.check_name("clippy") &&
+        attr.meta_item_list().map_or(false, |list| {
+            list.len() == 1 && match list[0].node {
+                ast::NestedMetaItemKind::MetaItem(ref it) => it.name == "author",
+                ast::NestedMetaItemKind::Literal(_) => false,
+            }
+        })
+    })
+}
+
+fn print_path(path: &QPath, first: &mut bool) {
+    match *path {
+        QPath::Resolved(_, ref path) => for segment in &path.segments {
+            if *first {
+                *first = false;
+            } else {
+                print!(", ");
+            }
+            print!("{:?}", segment.name.as_str());
+        },
+        QPath::TypeRelative(ref ty, ref segment) => {
+            match ty.node {
+                hir::Ty_::TyPath(ref inner_path) => {
+                    print_path(inner_path, first);
+                    if *first {
+                        *first = false;
+                    } else {
+                        print!(", ");
+                    }
+                    print!("{:?}", segment.name.as_str());
+                },
+                ref other => print!("/* unimplemented: {:?}*/", other),
+            }
+        },
+    }
+}

clippy_lints/src/utils/mod.rs

@@ -29,6 +29,7 @@ pub mod paths;
 pub mod sugg;
 pub mod inspector;
 pub mod internal_lints;
+pub mod author;
 pub use self::hir_utils::{SpanlessEq, SpanlessHash};
 
 pub type MethodArgs = HirVec<P<Expr>>;