Merge pull request #2151 from gbip/master

Implementation of the `const_static_lifetime` lint.

Author: oli-obk

clippy_lints/src/approx_const.rs

@@ -33,7 +33,7 @@ declare_lint! {
 }
 
 // Tuples are of the form (constant, name, min_digits)
-const KNOWN_CONSTS: &'static [(f64, &'static str, usize)] = &[
+const KNOWN_CONSTS: &[(f64, &str, usize)] = &[
     (f64::E, "E", 4),
     (f64::FRAC_1_PI, "FRAC_1_PI", 4),
     (f64::FRAC_1_SQRT_2, "FRAC_1_SQRT_2", 5),

clippy_lints/src/block_in_if_condition.rs

@@ -71,8 +71,8 @@ impl<'a, 'tcx: 'a> Visitor<'tcx> for ExVisitor<'a, 'tcx> {
     }
 }
 
-const BRACED_EXPR_MESSAGE: &'static str = "omit braces around single expression condition";
-const COMPLEX_BLOCK_MESSAGE: &'static str = "in an 'if' condition, avoid complex blocks or closures with blocks; \
+const BRACED_EXPR_MESSAGE: &str = "omit braces around single expression condition";
+const COMPLEX_BLOCK_MESSAGE: &str = "in an 'if' condition, avoid complex blocks or closures with blocks; \
                                              instead, move the block or closure higher and bind it with a 'let'";
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BlockInIfCondition {

clippy_lints/src/const_static_lifetime.rs

@@ -0,0 +1,84 @@
+use syntax::ast::{Item, ItemKind, TyKind, Ty};
+use rustc::lint::{LintPass, EarlyLintPass, LintArray, EarlyContext};
+use utils::{span_lint_and_then, in_macro};
+
+/// **What it does:** Checks for constants with an explicit `'static` lifetime.
+///
+/// **Why is this bad?** Adding `'static` to every reference can create very
+/// complicated types.
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rust
+/// const FOO: &'static [(&'static str, &'static str, fn(&Bar) -> bool)] =
+/// &[...]
+/// ```
+/// This code can be rewritten as
+/// ```rust
+///  const FOO: &[(&str, &str, fn(&Bar) -> bool)] = &[...]
+/// ```
+
+declare_lint! {
+    pub CONST_STATIC_LIFETIME, 
+    Warn,
+    "Using explicit `'static` lifetime for constants when elision rules would allow omitting them."
+}
+
+pub struct StaticConst;
+
+impl LintPass for StaticConst {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(CONST_STATIC_LIFETIME)
+    }
+}
+
+impl StaticConst {
+    // Recursively visit types
+    fn visit_type(&mut self, ty: &Ty, cx: &EarlyContext) {
+        match ty.node {
+            // Be carefull of nested structures (arrays and tuples)
+            TyKind::Array(ref ty, _) => {
+                self.visit_type(&*ty, cx);
+            },
+            TyKind::Tup(ref tup) => {
+                for tup_ty in tup {
+                    self.visit_type(&*tup_ty, cx);
+                }
+            },
+            // This is what we are looking for !
+            TyKind::Rptr(ref optional_lifetime, ref borrow_type) => {
+                // Match the 'static lifetime
+                if let Some(lifetime) = *optional_lifetime {
+                    if let TyKind::Path(_, _) = borrow_type.ty.node {
+                        // Verify that the path is a str
+                        if lifetime.ident.name == "'static" {
+                            let mut sug: String = String::new();
+                            span_lint_and_then(cx,
+                                               CONST_STATIC_LIFETIME,
+                                               lifetime.span,
+                                               "Constants have by default a `'static` lifetime",
+                                               |db| {db.span_suggestion(lifetime.span,"consider removing `'static`",sug);});
+                        }
+                    }
+                }
+                self.visit_type(&*borrow_type.ty, cx);
+            },
+            TyKind::Slice(ref ty) => {
+                self.visit_type(ty, cx);
+            },
+            _ => {},
+        }
+    }
+}
+
+impl EarlyLintPass for StaticConst {
+    fn check_item(&mut self, cx: &EarlyContext, item: &Item) {
+        if !in_macro(item.span) {
+            // Match only constants...
+            if let ItemKind::Const(ref var_type, _) = item.node {
+                self.visit_type(var_type, cx);
+            }
+        }
+    }
+}

clippy_lints/src/doc.rs

@@ -88,7 +88,7 @@ impl<'a> Iterator for Parser<'a> {
 #[allow(cast_possible_truncation)]
 pub fn strip_doc_comment_decoration(comment: &str, span: Span) -> (String, Vec<(usize, Span)>) {
     // one-line comments lose their prefix
-    const ONELINERS: &'static [&'static str] = &["///!", "///", "//!", "//"];
+    const ONELINERS: &[&str] = &["///!", "///", "//!", "//"];
     for prefix in ONELINERS {
         if comment.starts_with(*prefix) {
             let doc = &comment[prefix.len()..];

clippy_lints/src/lib.rs

@@ -76,6 +76,7 @@ pub mod block_in_if_condition;
 pub mod booleans;
 pub mod bytecount;
 pub mod collapsible_if;
+pub mod const_static_lifetime;
 pub mod copies;
 pub mod cyclomatic_complexity;
 pub mod derive;
@@ -339,6 +340,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
     reg.register_late_lint_pass(box invalid_ref::InvalidRef);
     reg.register_late_lint_pass(box identity_conversion::IdentityConversion::default());
     reg.register_late_lint_pass(box types::ImplicitHasher);
+    reg.register_early_lint_pass(box const_static_lifetime::StaticConst);
 
     reg.register_lint_group("clippy_restrictions", vec![
         arithmetic::FLOAT_ARITHMETIC,
@@ -349,6 +351,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
 
     reg.register_lint_group("clippy_pedantic", vec![
         booleans::NONMINIMAL_BOOL,
+        const_static_lifetime::CONST_STATIC_LIFETIME,
         empty_enum::EMPTY_ENUM,
         enum_glob_use::ENUM_GLOB_USE,
         enum_variants::PUB_ENUM_VARIANT_NAMES,

clippy_lints/src/methods.rs

@@ -1531,7 +1531,7 @@ enum Convention {
 }
 
 #[cfg_attr(rustfmt, rustfmt_skip)]
-const CONVENTIONS: [(Convention, &'static [SelfKind]); 6] = [
+const CONVENTIONS: [(Convention, &[SelfKind]); 6] = [
     (Convention::Eq("new"), &[SelfKind::No]),
     (Convention::StartsWith("as_"), &[SelfKind::Ref, SelfKind::RefMut]),
     (Convention::StartsWith("from_"), &[SelfKind::No]),
@@ -1541,7 +1541,7 @@ const CONVENTIONS: [(Convention, &'static [SelfKind]); 6] = [
 ];
 
 #[cfg_attr(rustfmt, rustfmt_skip)]
-const TRAIT_METHODS: [(&'static str, usize, SelfKind, OutType, &'static str); 30] = [
+const TRAIT_METHODS: [(&str, usize, SelfKind, OutType, &str); 30] = [
     ("add", 2, SelfKind::Value, OutType::Any, "std::ops::Add"),
     ("as_mut", 1, SelfKind::RefMut, OutType::Ref, "std::convert::AsMut"),
     ("as_ref", 1, SelfKind::Ref, OutType::Ref, "std::convert::AsRef"),
@@ -1575,7 +1575,7 @@ const TRAIT_METHODS: [(&'static str, usize, SelfKind, OutType, &'static str); 30
 ];
 
 #[cfg_attr(rustfmt, rustfmt_skip)]
-const PATTERN_METHODS: [(&'static str, usize); 17] = [
+const PATTERN_METHODS: [(&str, usize); 17] = [
     ("contains", 1),
     ("starts_with", 1),
     ("ends_with", 1),

clippy_lints/src/needless_continue.rs

@@ -252,15 +252,15 @@ struct LintData<'a> {
     block_stmts: &'a [ast::Stmt],
 }
 
-const MSG_REDUNDANT_ELSE_BLOCK: &'static str = "This else block is redundant.\n";
+const MSG_REDUNDANT_ELSE_BLOCK: &str = "This else block is redundant.\n";
 
-const MSG_ELSE_BLOCK_NOT_NEEDED: &'static str = "There is no need for an explicit `else` block for this `if` \
+const MSG_ELSE_BLOCK_NOT_NEEDED: &str = "There is no need for an explicit `else` block for this `if` \
                                                  expression\n";
 
-const DROP_ELSE_BLOCK_AND_MERGE_MSG: &'static str = "Consider dropping the else clause and merging the code that \
+const DROP_ELSE_BLOCK_AND_MERGE_MSG: &str = "Consider dropping the else clause and merging the code that \
                                                      follows (in the loop) with the if block, like so:\n";
 
-const DROP_ELSE_BLOCK_MSG: &'static str = "Consider dropping the else clause, and moving out the code in the else \
+const DROP_ELSE_BLOCK_MSG: &str = "Consider dropping the else clause, and moving out the code in the else \
                                            block, like so:\n";
 
 

clippy_lints/src/non_expressive_names.rs

@@ -69,7 +69,7 @@ struct SimilarNamesLocalVisitor<'a, 'tcx: 'a> {
 // this list contains lists of names that are allowed to be similar
 // the assumption is that no name is ever contained in multiple lists.
 #[cfg_attr(rustfmt, rustfmt_skip)]
-const WHITELIST: &'static [&'static [&'static str]] = &[
+const WHITELIST: &[&[&str]] = &[
     &["parsed", "parser"],
     &["lhs", "rhs"],
     &["tx", "rx"],

clippy_lints/src/utils/conf.rs

@@ -182,7 +182,7 @@ define_Conf! {
 /// Search for the configuration file.
 pub fn lookup_conf_file() -> io::Result<Option<path::PathBuf>> {
     /// Possible filename to search for.
-    const CONFIG_FILE_NAMES: [&'static str; 2] = [".clippy.toml", "clippy.toml"];
+    const CONFIG_FILE_NAMES: [&str; 2] = [".clippy.toml", "clippy.toml"];
 
     let mut current = try!(env::current_dir());
 

clippy_lints/src/utils/constants.rs

@@ -7,7 +7,7 @@
 /// See also [the reference][reference-types] for a list of such types.
 ///
 /// [reference-types]: https://doc.rust-lang.org/reference.html#types
-pub const BUILTIN_TYPES: &'static [&'static str] = &[
+pub const BUILTIN_TYPES: &[&str] = &[
     "i8",
     "u8",
     "i16",

clippy_lints/src/utils/mod.rs

@@ -169,7 +169,7 @@ pub fn match_def_path(tcx: TyCtxt, def_id: DefId, path: &[&str]) -> bool {
 
     impl ty::item_path::ItemPathBuffer for AbsolutePathBuffer {
         fn root_mode(&self) -> &ty::item_path::RootMode {
-            const ABSOLUTE: &'static ty::item_path::RootMode = &ty::item_path::RootMode::Absolute;
+            const ABSOLUTE: &ty::item_path::RootMode = &ty::item_path::RootMode::Absolute;
             ABSOLUTE
         }