Auto merge of #6081 - ilknarf:master, r=matthiaskrgr

New Lint: disallowed_method

Fixes https://github.com/rust-lang/rust-clippy/issues/6073

I added a `disallowed_method` lint that works similar to `blacklisted_name`, e.g allows config-defined disallowed method calls.

This lint allows advanced users to patch in undesired method calls for specific projects. It basically uses the DefId of method calls and matches it to parsed strings. Is there an alternative approach that could use more easily digestible configuration strings?

All tests pass as expected except for a linting error on `ui/redundant_pattern_matching_option`, which I am not sure how to resolve since I don't think I changed anything affecting it.

changelog: Add disallowed_method lint to warn on user-defined method calls

10 files changed, 121 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d1dfe36ffd8..575cbd60792 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1559,6 +1559,7 @@ Released 2018-09-13
 [`deref_addrof`]: https://rust-lang.github.io/rust-clippy/master/index.html#deref_addrof
 [`derive_hash_xor_eq`]: https://rust-lang.github.io/rust-clippy/master/index.html#derive_hash_xor_eq
 [`derive_ord_xor_partial_ord`]: https://rust-lang.github.io/rust-clippy/master/index.html#derive_ord_xor_partial_ord
+[`disallowed_method`]: https://rust-lang.github.io/rust-clippy/master/index.html#disallowed_method
 [`diverging_sub_expression`]: https://rust-lang.github.io/rust-clippy/master/index.html#diverging_sub_expression
 [`doc_markdown`]: https://rust-lang.github.io/rust-clippy/master/index.html#doc_markdown
 [`double_comparisons`]: https://rust-lang.github.io/rust-clippy/master/index.html#double_comparisons
diff --git a/README.md b/README.md
index a2984d73641..62a8be0abf2 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are over 350 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are over 400 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
 
diff --git a/clippy_lints/src/disallowed_method.rs b/clippy_lints/src/disallowed_method.rs
new file mode 100644
index 00000000000..581c3242e37
--- /dev/null
+++ b/clippy_lints/src/disallowed_method.rs
@@ -0,0 +1,73 @@
+use crate::utils::span_lint;
+
+use rustc_data_structures::fx::FxHashSet;
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::Symbol;
+
+declare_clippy_lint! {
+    /// **What it does:** Lints for specific trait methods defined in clippy.toml
+    ///
+    /// **Why is this bad?** Some methods are undesirable in certain contexts,
+    /// and it would be beneficial to lint for them as needed.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust,ignore
+    /// // example code where clippy issues a warning
+    /// foo.bad_method(); // Foo::bad_method is disallowed in the configuration
+    /// ```
+    /// Use instead:
+    /// ```rust,ignore
+    /// // example code which does not raise clippy warning
+    /// goodStruct.bad_method(); // GoodStruct::bad_method is not disallowed
+    /// ```
+    pub DISALLOWED_METHOD,
+    nursery,
+    "use of a disallowed method call"
+}
+
+#[derive(Clone, Debug)]
+pub struct DisallowedMethod {
+    disallowed: FxHashSet<Vec<Symbol>>,
+}
+
+impl DisallowedMethod {
+    pub fn new(disallowed: &FxHashSet<String>) -> Self {
+        Self {
+            disallowed: disallowed
+                .iter()
+                .map(|s| s.split("::").map(|seg| Symbol::intern(seg)).collect::<Vec<_>>())
+                .collect(),
+        }
+    }
+}
+
+impl_lint_pass!(DisallowedMethod => [DISALLOWED_METHOD]);
+
+impl<'tcx> LateLintPass<'tcx> for DisallowedMethod {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        if let ExprKind::MethodCall(_path, _, _args, _) = &expr.kind {
+            let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
+
+            let method_call = cx.get_def_path(def_id);
+            if self.disallowed.contains(&method_call) {
+                let method = method_call
+                    .iter()
+                    .map(|s| s.to_ident_string())
+                    .collect::<Vec<_>>()
+                    .join("::");
+
+                span_lint(
+                    cx,
+                    DISALLOWED_METHOD,
+                    expr.span,
+                    &format!("use of a disallowed method `{}`", method),
+                );
+            }
+        }
+    }
+}
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 58112ac8da5..7b6efc660af 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -175,6 +175,7 @@ mod dbg_macro;
 mod default_trait_access;
 mod dereference;
 mod derive;
+mod disallowed_method;
 mod doc;
 mod double_comparison;
 mod double_parens;
@@ -525,6 +526,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &derive::DERIVE_ORD_XOR_PARTIAL_ORD,
         &derive::EXPL_IMPL_CLONE_ON_COPY,
         &derive::UNSAFE_DERIVE_DESERIALIZE,
+        &disallowed_method::DISALLOWED_METHOD,
         &doc::DOC_MARKDOWN,
         &doc::MISSING_ERRORS_DOC,
         &doc::MISSING_SAFETY_DOC,
@@ -1118,6 +1120,9 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box async_yields_async::AsyncYieldsAsync);
     store.register_late_pass(|| box manual_strip::ManualStrip);
     store.register_late_pass(|| box utils::internal_lints::MatchTypeOnDiagItem);
+    let disallowed_methods = conf.disallowed_methods.iter().cloned().collect::<FxHashSet<_>>();
+    store.register_late_pass(move || box disallowed_method::DisallowedMethod::new(&disallowed_methods));
+
 
     store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
         LintId::of(&arithmetic::FLOAT_ARITHMETIC),
@@ -1807,6 +1812,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_group(true, "clippy::nursery", Some("clippy_nursery"), vec![
         LintId::of(&attrs::EMPTY_LINE_AFTER_OUTER_ATTR),
         LintId::of(&cognitive_complexity::COGNITIVE_COMPLEXITY),
+        LintId::of(&disallowed_method::DISALLOWED_METHOD),
         LintId::of(&fallible_impl_from::FALLIBLE_IMPL_FROM),
         LintId::of(&floating_point_arithmetic::IMPRECISE_FLOPS),
         LintId::of(&floating_point_arithmetic::SUBOPTIMAL_FLOPS),
diff --git a/clippy_lints/src/utils/conf.rs b/clippy_lints/src/utils/conf.rs
index 9c5a12ea9c8..03f8c5a2c07 100644
--- a/clippy_lints/src/utils/conf.rs
+++ b/clippy_lints/src/utils/conf.rs
@@ -164,6 +164,8 @@ define_Conf! {
     (max_fn_params_bools, "max_fn_params_bools": u64, 3),
     /// Lint: WILDCARD_IMPORTS. Whether to allow certain wildcard imports (prelude, super in tests).
     (warn_on_all_wildcard_imports, "warn_on_all_wildcard_imports": bool, false),
+    /// Lint: DISALLOWED_METHOD. The list of blacklisted methods to lint about. NB: `bar` is not here since it has legitimate uses
+    (disallowed_methods, "disallowed_methods": Vec<String>, Vec::<String>::new()),
 }
 
 impl Default for Conf {
diff --git a/src/lintlist/mod.rs b/src/lintlist/mod.rs
index 9603023ed06..76e655ad603 100644
--- a/src/lintlist/mod.rs
+++ b/src/lintlist/mod.rs
@@ -382,6 +382,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         module: "derive",
     },
     Lint {
+        name: "disallowed_method",
+        group: "nursery",
+        desc: "use of a disallowed method call",
+        deprecation: None,
+        module: "disallowed_method",
+    },
+    Lint {
         name: "diverging_sub_expression",
         group: "complexity",
         desc: "whether an expression contains a diverging sub expression",
diff --git a/tests/ui-toml/toml_disallowed_method/clippy.toml b/tests/ui-toml/toml_disallowed_method/clippy.toml
new file mode 100644
index 00000000000..a1f515e443d
--- /dev/null
+++ b/tests/ui-toml/toml_disallowed_method/clippy.toml
@@ -0,0 +1 @@
+disallowed-methods = ["core::iter::traits::iterator::Iterator::sum", "regex::re_unicode::Regex::is_match"]
diff --git a/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.rs b/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.rs
new file mode 100644
index 00000000000..3d3f0729abd
--- /dev/null
+++ b/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.rs
@@ -0,0 +1,13 @@
+#![warn(clippy::disallowed_method)]
+
+extern crate regex;
+use regex::Regex;
+
+fn main() {
+    let a = vec![1, 2, 3, 4];
+    let re = Regex::new(r"ab.*c").unwrap();
+
+    re.is_match("abc");
+
+    a.iter().sum::<i32>();
+}
diff --git a/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr b/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr
new file mode 100644
index 00000000000..ed91b5a6796
--- /dev/null
+++ b/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr
@@ -0,0 +1,16 @@
+error: use of a disallowed method `regex::re_unicode::Regex::is_match`
+  --> $DIR/conf_disallowed_method.rs:10:5
+   |
+LL |     re.is_match("abc");
+   |     ^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::disallowed-method` implied by `-D warnings`
+
+error: use of a disallowed method `core::iter::traits::iterator::Iterator::sum`
+  --> $DIR/conf_disallowed_method.rs:12:5
+   |
+LL |     a.iter().sum::<i32>();
+   |     ^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr b/tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr
index 6fbba01416a..103ec27e7d7 100644
--- a/tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr
+++ b/tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr
@@ -1,4 +1,4 @@
-error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `blacklisted-names`, `cognitive-complexity-threshold`, `cyclomatic-complexity-threshold`, `doc-valid-idents`, `too-many-arguments-threshold`, `type-complexity-threshold`, `single-char-binding-names-threshold`, `too-large-for-stack`, `enum-variant-name-threshold`, `enum-variant-size-threshold`, `verbose-bit-mask-threshold`, `literal-representation-threshold`, `trivial-copy-size-limit`, `too-many-lines-threshold`, `array-size-threshold`, `vec-box-size-threshold`, `max-trait-bounds`, `max-struct-bools`, `max-fn-params-bools`, `warn-on-all-wildcard-imports`, `third-party` at line 5 column 1
+error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `blacklisted-names`, `cognitive-complexity-threshold`, `cyclomatic-complexity-threshold`, `doc-valid-idents`, `too-many-arguments-threshold`, `type-complexity-threshold`, `single-char-binding-names-threshold`, `too-large-for-stack`, `enum-variant-name-threshold`, `enum-variant-size-threshold`, `verbose-bit-mask-threshold`, `literal-representation-threshold`, `trivial-copy-size-limit`, `too-many-lines-threshold`, `array-size-threshold`, `vec-box-size-threshold`, `max-trait-bounds`, `max-struct-bools`, `max-fn-params-bools`, `warn-on-all-wildcard-imports`, `disallowed-methods`, `third-party` at line 5 column 1
 
 error: aborting due to previous error