Doctests: Fix all complexity lint docs

cc #4319

33 files changed, 155 insertions, 83 deletions

diff --git a/clippy_lints/src/assign_ops.rs b/clippy_lints/src/assign_ops.rs
index 28a5f8246f7..ec4c8f5faa3 100644
--- a/clippy_lints/src/assign_ops.rs
+++ b/clippy_lints/src/assign_ops.rs
@@ -45,7 +45,8 @@ declare_clippy_lint! {
     /// **Example:**
     /// ```rust
     /// let mut a = 5;
-    /// ...
+    /// let b = 2;
+    /// // ...
     /// a += a + b;
     /// ```
     pub MISREFACTORED_ASSIGN_OP,
diff --git a/clippy_lints/src/double_comparison.rs b/clippy_lints/src/double_comparison.rs
index 0c7c81f40bf..d48bfea73b3 100644
--- a/clippy_lints/src/double_comparison.rs
+++ b/clippy_lints/src/double_comparison.rs
@@ -18,13 +18,17 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// x == y || x < y
+    /// # let x = 1;
+    /// # let y = 2;
+    /// if x == y || x < y {}
     /// ```
     ///
     /// Could be written as:
     ///
     /// ```rust
-    /// x <= y
+    /// # let x = 1;
+    /// # let y = 2;
+    /// if x <= y {}
     /// ```
     pub DOUBLE_COMPARISONS,
     complexity,
diff --git a/clippy_lints/src/double_parens.rs b/clippy_lints/src/double_parens.rs
index f39ea6a3cc5..e55490325ec 100644
--- a/clippy_lints/src/double_parens.rs
+++ b/clippy_lints/src/double_parens.rs
@@ -13,9 +13,10 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// ((0))
-    /// foo((0))
-    /// ((1, 2))
+    /// # fn foo(bar: usize) {}
+    /// ((0));
+    /// foo((0));
+    /// ((1, 2));
     /// ```
     pub DOUBLE_PARENS,
     complexity,
diff --git a/clippy_lints/src/duration_subsec.rs b/clippy_lints/src/duration_subsec.rs
index 60470ede541..1346aea3ed0 100644
--- a/clippy_lints/src/duration_subsec.rs
+++ b/clippy_lints/src/duration_subsec.rs
@@ -20,6 +20,7 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
+    /// # use std::time::Duration;
     /// let dur = Duration::new(5, 0);
     /// let _micros = dur.subsec_nanos() / 1_000;
     /// let _millis = dur.subsec_nanos() / 1_000_000;
diff --git a/clippy_lints/src/eval_order_dependence.rs b/clippy_lints/src/eval_order_dependence.rs
index 2db3a2bc00b..b915d50671b 100644
--- a/clippy_lints/src/eval_order_dependence.rs
+++ b/clippy_lints/src/eval_order_dependence.rs
@@ -42,7 +42,9 @@ declare_clippy_lint! {
     /// shorthand.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,no_run
+    /// # fn b() -> bool { true }
+    /// # fn c() -> bool { true }
     /// let a = b() || panic!() || c();
     /// // `c()` is dead, `panic!()` is only called if `b()` returns `false`
     /// let x = (a, b, c, panic!());
diff --git a/clippy_lints/src/explicit_write.rs b/clippy_lints/src/explicit_write.rs
index dc76bb0b2b9..a2edb4855b6 100644
--- a/clippy_lints/src/explicit_write.rs
+++ b/clippy_lints/src/explicit_write.rs
@@ -16,8 +16,10 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
+    /// # use std::io::Write;
+    /// # let bar = "furchtbar";
     /// // this would be clearer as `eprintln!("foo: {:?}", bar);`
-    /// writeln!(&mut io::stderr(), "foo: {:?}", bar).unwrap();
+    /// writeln!(&mut std::io::stderr(), "foo: {:?}", bar).unwrap();
     /// ```
     pub EXPLICIT_WRITE,
     complexity,
diff --git a/clippy_lints/src/format.rs b/clippy_lints/src/format.rs
index aed1142d9ae..751d8fd0083 100644
--- a/clippy_lints/src/format.rs
+++ b/clippy_lints/src/format.rs
@@ -26,8 +26,9 @@ declare_clippy_lint! {
     ///
     /// **Examples:**
     /// ```rust
-    /// format!("foo")
-    /// format!("{}", foo)
+    /// # let foo = "foo";
+    /// format!("foo");
+    /// format!("{}", foo);
     /// ```
     pub USELESS_FORMAT,
     complexity,
diff --git a/clippy_lints/src/functions.rs b/clippy_lints/src/functions.rs
index 1a163e682ef..9772a603ba0 100644
--- a/clippy_lints/src/functions.rs
+++ b/clippy_lints/src/functions.rs
@@ -23,8 +23,9 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
+    /// # struct Color;
     /// fn foo(x: u32, y: u32, name: &str, c: Color, w: f32, h: f32, a: f32, b: f32) {
-    ///     ..
+    ///     // ..
     /// }
     /// ```
     pub TOO_MANY_ARGUMENTS,
diff --git a/clippy_lints/src/identity_op.rs b/clippy_lints/src/identity_op.rs
index b3ab46781ad..1cd58a37094 100644
--- a/clippy_lints/src/identity_op.rs
+++ b/clippy_lints/src/identity_op.rs
@@ -17,7 +17,8 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// x / 1 + 0 * 1 - 0 | 0
+    /// # let x = 1;
+    /// x / 1 + 0 * 1 - 0 | 0;
     /// ```
     pub IDENTITY_OP,
     complexity,
diff --git a/clippy_lints/src/int_plus_one.rs b/clippy_lints/src/int_plus_one.rs
index b59179618a6..22ebf562d3b 100644
--- a/clippy_lints/src/int_plus_one.rs
+++ b/clippy_lints/src/int_plus_one.rs
@@ -17,13 +17,17 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// x >= y + 1
+    /// # let x = 1;
+    /// # let y = 1;
+    /// if x >= y + 1 {}
     /// ```
     ///
-    /// Could be written:
+    /// Could be written as:
     ///
     /// ```rust
-    /// x > y
+    /// # let x = 1;
+    /// # let y = 1;
+    /// if x > y {}
     /// ```
     pub INT_PLUS_ONE,
     complexity,
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 1e9e17f599c..d05e815c231 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -100,7 +100,7 @@ macro_rules! declare_clippy_lint {
     };
     { $(#[$attr:meta])* pub $name:tt, complexity, $description:tt } => {
         declare_tool_lint! {
-            pub clippy::$name, Warn, $description, report_in_external_macro: true
+            $(#[$attr])* pub clippy::$name, Warn, $description, report_in_external_macro: true
         }
     };
     { $(#[$attr:meta])* pub $name:tt, perf, $description:tt } => {
diff --git a/clippy_lints/src/lifetimes.rs b/clippy_lints/src/lifetimes.rs
index 47cced9d9a4..73d4a32574b 100644
--- a/clippy_lints/src/lifetimes.rs
+++ b/clippy_lints/src/lifetimes.rs
@@ -47,7 +47,7 @@ declare_clippy_lint! {
     /// **Example:**
     /// ```rust
     /// fn unused_lifetime<'a>(x: u8) {
-    ///     ..
+    ///     // ..
     /// }
     /// ```
     pub EXTRA_UNUSED_LIFETIMES,
diff --git a/clippy_lints/src/loops.rs b/clippy_lints/src/loops.rs
index 02074c79b41..3c66c74324e 100644
--- a/clippy_lints/src/loops.rs
+++ b/clippy_lints/src/loops.rs
@@ -217,18 +217,19 @@ declare_clippy_lint! {
     /// **Known problems:** Sometimes the wrong binding is displayed (#383).
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,no_run
+    /// # let y = Some(1);
     /// loop {
     ///     let x = match y {
     ///         Some(x) => x,
     ///         None => break,
-    ///     }
+    ///     };
     ///     // .. do something with x
     /// }
     /// // is easier written as
     /// while let Some(x) = y {
     ///     // .. do something with x
-    /// }
+    /// };
     /// ```
     pub WHILE_LET_LOOP,
     complexity,
@@ -309,8 +310,11 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```ignore
-    /// for i in 0..v.len() { foo(v[i]);
+    /// ```rust
+    /// # let v = vec![1];
+    /// # fn foo(bar: usize) {}
+    /// # fn bar(bar: usize, baz: usize) {}
+    /// for i in 0..v.len() { foo(v[i]); }
     /// for i in 0..v.len() { bar(i, v[i]); }
     /// ```
     pub EXPLICIT_COUNTER_LOOP,
diff --git a/clippy_lints/src/map_unit_fn.rs b/clippy_lints/src/map_unit_fn.rs
index 2e97f44b317..22093bfbee8 100644
--- a/clippy_lints/src/map_unit_fn.rs
+++ b/clippy_lints/src/map_unit_fn.rs
@@ -20,20 +20,29 @@ declare_clippy_lint! {
     /// **Example:**
     ///
     /// ```rust
-    /// let x: Option<&str> = do_stuff();
+    /// # fn do_stuff() -> Option<String> { Some(String::new()) }
+    /// # fn log_err_msg(foo: String) -> Option<String> { Some(foo) }
+    /// # fn format_msg(foo: String) -> String { String::new() }
+    /// let x: Option<String> = do_stuff();
     /// x.map(log_err_msg);
-    /// x.map(|msg| log_err_msg(format_msg(msg)))
+    /// # let x: Option<String> = do_stuff();
+    /// x.map(|msg| log_err_msg(format_msg(msg)));
     /// ```
     ///
     /// The correct use would be:
     ///
     /// ```rust
-    /// let x: Option<&str> = do_stuff();
+    /// # fn do_stuff() -> Option<String> { Some(String::new()) }
+    /// # fn log_err_msg(foo: String) -> Option<String> { Some(foo) }
+    /// # fn format_msg(foo: String) -> String { String::new() }
+    /// let x: Option<String> = do_stuff();
     /// if let Some(msg) = x {
-    ///     log_err_msg(msg)
+    ///     log_err_msg(msg);
     /// }
+    ///
+    /// # let x: Option<String> = do_stuff();
     /// if let Some(msg) = x {
-    ///     log_err_msg(format_msg(msg))
+    ///     log_err_msg(format_msg(msg));
     /// }
     /// ```
     pub OPTION_MAP_UNIT_FN,
@@ -53,21 +62,29 @@ declare_clippy_lint! {
     /// **Example:**
     ///
     /// ```rust
-    /// let x: Result<&str, &str> = do_stuff();
+    /// # fn do_stuff() -> Result<String, String> { Ok(String::new()) }
+    /// # fn log_err_msg(foo: String) -> Result<String, String> { Ok(foo) }
+    /// # fn format_msg(foo: String) -> String { String::new() }
+    /// let x: Result<String, String> = do_stuff();
     /// x.map(log_err_msg);
-    /// x.map(|msg| log_err_msg(format_msg(msg)))
+    /// # let x: Result<String, String> = do_stuff();
+    /// x.map(|msg| log_err_msg(format_msg(msg)));
     /// ```
     ///
     /// The correct use would be:
     ///
     /// ```rust
-    /// let x: Result<&str, &str> = do_stuff();
+    /// # fn do_stuff() -> Result<String, String> { Ok(String::new()) }
+    /// # fn log_err_msg(foo: String) -> Result<String, String> { Ok(foo) }
+    /// # fn format_msg(foo: String) -> String { String::new() }
+    /// let x: Result<String, String> = do_stuff();
     /// if let Ok(msg) = x {
-    ///     log_err_msg(msg)
-    /// }
+    ///     log_err_msg(msg);
+    /// };
+    /// # let x: Result<String, String> = do_stuff();
     /// if let Ok(msg) = x {
-    ///     log_err_msg(format_msg(msg))
-    /// }
+    ///     log_err_msg(format_msg(msg));
+    /// };
     /// ```
     pub RESULT_MAP_UNIT_FN,
     complexity,
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
index 02dfb3e32aa..473f3892f22 100644
--- a/clippy_lints/src/methods/mod.rs
+++ b/clippy_lints/src/methods/mod.rs
@@ -247,7 +247,8 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// iter.filter(|x| x == 0).next()
+    /// # let vec = vec![1];
+    /// vec.iter().filter(|x| **x == 0).next();
     /// ```
     pub FILTER_NEXT,
     complexity,
@@ -345,7 +346,8 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// iter.find(|x| x == 0).is_some()
+    /// # let vec = vec![1];
+    /// vec.iter().find(|x| **x == 0).is_some();
     /// ```
     pub SEARCH_IS_SOME,
     complexity,
@@ -363,7 +365,8 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// name.chars().next() == Some('_')
+    /// let name = "foo";
+    /// name.chars().next() == Some('_');
     /// ```
     pub CHARS_NEXT_CMP,
     complexity,
@@ -434,7 +437,7 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// 42u64.clone()
+    /// 42u64.clone();
     /// ```
     pub CLONE_ON_COPY,
     complexity,
@@ -708,11 +711,13 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
+    /// # fn do_stuff(x: &[i32]) {}
     /// let x: &[i32] = &[1, 2, 3, 4, 5];
     /// do_stuff(x.as_ref());
     /// ```
     /// The correct use would be:
     /// ```rust
+    /// # fn do_stuff(x: &[i32]) {}
     /// let x: &[i32] = &[1, 2, 3, 4, 5];
     /// do_stuff(x);
     /// ```
diff --git a/clippy_lints/src/misc.rs b/clippy_lints/src/misc.rs
index d89f886a39b..6d24aa008fb 100644
--- a/clippy_lints/src/misc.rs
+++ b/clippy_lints/src/misc.rs
@@ -184,7 +184,7 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// f() && g(); // We should write `if f() { g(); }`.
     /// ```
     pub SHORT_CIRCUIT_STATEMENT,
diff --git a/clippy_lints/src/misc_early.rs b/clippy_lints/src/misc_early.rs
index c9df436dae7..7d6f29c521b 100644
--- a/clippy_lints/src/misc_early.rs
+++ b/clippy_lints/src/misc_early.rs
@@ -53,7 +53,7 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// (|| 42)()
     /// ```
     pub REDUNDANT_CLOSURE_CALL,
diff --git a/clippy_lints/src/needless_bool.rs b/clippy_lints/src/needless_bool.rs
index 9857e17563c..167f00fee51 100644
--- a/clippy_lints/src/needless_bool.rs
+++ b/clippy_lints/src/needless_bool.rs
@@ -24,7 +24,7 @@ declare_clippy_lint! {
     /// shorter code.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// if x {
     ///     false
     /// } else {
@@ -46,7 +46,7 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// if x == true {} // could be `if x { }`
     /// ```
     pub BOOL_COMPARISON,
diff --git a/clippy_lints/src/needless_borrowed_ref.rs b/clippy_lints/src/needless_borrowed_ref.rs
index b6104f6cc9a..b6598ac55b3 100644
--- a/clippy_lints/src/needless_borrowed_ref.rs
+++ b/clippy_lints/src/needless_borrowed_ref.rs
@@ -18,7 +18,7 @@ declare_clippy_lint! {
     ///
     /// **Known problems:** It seems that the `&ref` pattern is sometimes useful.
     /// For instance in the following snippet:
-    /// ```rust
+    /// ```rust,ignore
     /// enum Animal {
     ///     Cat(u64),
     ///     Dog(u64),
@@ -26,8 +26,7 @@ declare_clippy_lint! {
     ///
     /// fn foo(a: &Animal, b: &Animal) {
     ///     match (a, b) {
-    /// (&Animal::Cat(v), k) | (k, &Animal::Cat(v)) => (), // lifetime
-    /// mismatch error
+    ///         (&Animal::Cat(v), k) | (k, &Animal::Cat(v)) => (), // lifetime mismatch error
     ///         (&Animal::Dog(ref c), &Animal::Dog(_)) => ()
     ///     }
     /// }
diff --git a/clippy_lints/src/needless_update.rs b/clippy_lints/src/needless_update.rs
index 316395acf26..fdaa14dfb6a 100644
--- a/clippy_lints/src/needless_update.rs
+++ b/clippy_lints/src/needless_update.rs
@@ -15,11 +15,17 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
+    /// # struct Point {
+    /// #     x: i32,
+    /// #     y: i32,
+    /// #     z: i32,
+    /// # }
+    /// # let zero_point = Point { x: 0, y: 0, z: 0 };
     /// Point {
     ///     x: 1,
-    ///     y: 0,
+    ///     y: 1,
     ///     ..zero_point
-    /// }
+    /// };
     /// ```
     pub NEEDLESS_UPDATE,
     complexity,
diff --git a/clippy_lints/src/no_effect.rs b/clippy_lints/src/no_effect.rs
index 8c5ddaf4140..2fe866a1d95 100644
--- a/clippy_lints/src/no_effect.rs
+++ b/clippy_lints/src/no_effect.rs
@@ -34,7 +34,7 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// compute_array()[0];
     /// ```
     pub UNNECESSARY_OPERATION,
diff --git a/clippy_lints/src/overflow_check_conditional.rs b/clippy_lints/src/overflow_check_conditional.rs
index c598e915a5a..f4c301958b9 100644
--- a/clippy_lints/src/overflow_check_conditional.rs
+++ b/clippy_lints/src/overflow_check_conditional.rs
@@ -14,7 +14,9 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// a + b < a
+    /// # let a = 1;
+    /// # let b = 2;
+    /// a + b < a;
     /// ```
     pub OVERFLOW_CHECK_CONDITIONAL,
     complexity,
diff --git a/clippy_lints/src/partialeq_ne_impl.rs b/clippy_lints/src/partialeq_ne_impl.rs
index 1091ed0d6de..805efa7cf20 100644
--- a/clippy_lints/src/partialeq_ne_impl.rs
+++ b/clippy_lints/src/partialeq_ne_impl.rs
@@ -19,7 +19,7 @@ declare_clippy_lint! {
     /// struct Foo;
     ///
     /// impl PartialEq for Foo {
-    ///    fn eq(&self, other: &Foo) -> bool { ... }
+    ///    fn eq(&self, other: &Foo) -> bool { true }
     ///    fn ne(&self, other: &Foo) -> bool { !(self == other) }
     /// }
     /// ```
diff --git a/clippy_lints/src/ranges.rs b/clippy_lints/src/ranges.rs
index af2342634a1..a0391e3364e 100644
--- a/clippy_lints/src/ranges.rs
+++ b/clippy_lints/src/ranges.rs
@@ -40,7 +40,8 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// x.iter().zip(0..x.len())
+    /// # let x = vec![1];
+    /// x.iter().zip(0..x.len());
     /// ```
     pub RANGE_ZIP_WITH_LEN,
     complexity,
@@ -60,7 +61,7 @@ declare_clippy_lint! {
     /// I.e., `let _ = (f()+1)..(f()+1)` results in `let _ = ((f()+1)..=f())`.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// for x..(y+1) { .. }
     /// ```
     pub RANGE_PLUS_ONE,
@@ -78,7 +79,7 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// for x..=(y-1) { .. }
     /// ```
     pub RANGE_MINUS_ONE,
diff --git a/clippy_lints/src/reference.rs b/clippy_lints/src/reference.rs
index 2ee00a2f103..35e214faae8 100644
--- a/clippy_lints/src/reference.rs
+++ b/clippy_lints/src/reference.rs
@@ -15,7 +15,7 @@ declare_clippy_lint! {
     /// the suggested fix for `x = **&&y` is `x = *&y`, which is still incorrect.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// let a = f(*&mut b);
     /// let c = *&d;
     /// ```
@@ -64,8 +64,8 @@ declare_clippy_lint! {
     /// **Example:**
     /// ```rust
     /// struct Point(u32, u32);
-    /// let point = Foo(30, 20);
-    /// let x = (&point).x;
+    /// let point = Point(30, 20);
+    /// let x = (&point).0;
     /// ```
     pub REF_IN_DEREF,
     complexity,
diff --git a/clippy_lints/src/swap.rs b/clippy_lints/src/swap.rs
index fc5b2150d52..11ab5b87628 100644
--- a/clippy_lints/src/swap.rs
+++ b/clippy_lints/src/swap.rs
@@ -20,12 +20,17 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
+    /// let mut a = 42;
+    /// let mut b = 1337;
+    ///
     /// let t = b;
     /// b = a;
     /// a = t;
     /// ```
     /// Use std::mem::swap():
     /// ```rust
+    /// let mut a = 1;
+    /// let mut b = 2;
     /// std::mem::swap(&mut a, &mut b);
     /// ```
     pub MANUAL_SWAP,
diff --git a/clippy_lints/src/trait_bounds.rs b/clippy_lints/src/trait_bounds.rs
index 8a719c0dd04..bf4c5d65db6 100644
--- a/clippy_lints/src/trait_bounds.rs
+++ b/clippy_lints/src/trait_bounds.rs
@@ -15,13 +15,13 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// pub fn foo<T>(t: T) where T: Copy, T: Clone
+    /// pub fn foo<T>(t: T) where T: Copy, T: Clone {}
     /// ```
     ///
     /// Could be written as:
     ///
     /// ```rust
-    /// pub fn foo<T>(t: T) where T: Copy + Clone
+    /// pub fn foo<T>(t: T) where T: Copy + Clone {}
     /// ```
     pub TYPE_REPETITION_IN_BOUNDS,
     complexity,
diff --git a/clippy_lints/src/transmute.rs b/clippy_lints/src/transmute.rs
index e2534dae09b..a514b9c512d 100644
--- a/clippy_lints/src/transmute.rs
+++ b/clippy_lints/src/transmute.rs
@@ -36,8 +36,8 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
-    /// core::intrinsics::transmute(t) // where the result type is the same as `t`'s
+    /// ```rust,ignore
+    /// core::intrinsics::transmute(t); // where the result type is the same as `t`'s
     /// ```
     pub USELESS_TRANSMUTE,
     complexity,
@@ -53,7 +53,7 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// core::intrinsics::transmute(t) // where the result type is the same as
     ///                                // `*t` or `&t`'s
     /// ```
@@ -70,8 +70,10 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
-    /// let _: &T = std::mem::transmute(p); // where p: *const T
+    /// ```rust,ignore
+    /// unsafe {
+    ///     let _: &T = std::mem::transmute(p); // where p: *const T
+    /// }
     ///
     /// // can be written:
     /// let _: &T = &*p;
@@ -99,7 +101,10 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// let _: char = std::mem::transmute(x); // where x: u32
+    /// let x = 1_u32;
+    /// unsafe {
+    ///     let _: char = std::mem::transmute(x); // where x: u32
+    /// }
     ///
     /// // should be:
     /// let _ = std::char::from_u32(x).unwrap();
@@ -127,7 +132,10 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// let _: &str = std::mem::transmute(b); // where b: &[u8]
+    /// let b: &[u8] = &[1_u8, 2_u8];
+    /// unsafe {
+    ///     let _: &str = std::mem::transmute(b); // where b: &[u8]
+    /// }
     ///
     /// // should be:
     /// let _ = std::str::from_utf8(b).unwrap();
@@ -146,7 +154,10 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// let _: bool = std::mem::transmute(x); // where x: u8
+    /// let x = 1_u8;
+    /// unsafe {
+    ///     let _: bool = std::mem::transmute(x); // where x: u8
+    /// }
     ///
     /// // should be:
     /// let _: bool = x != 0;
@@ -166,10 +177,12 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// let _: f32 = std::mem::transmute(x); // where x: u32
+    /// unsafe {
+    ///     let _: f32 = std::mem::transmute(1_u32); // where x: u32
+    /// }
     ///
     /// // should be:
-    /// let _: f32 = f32::from_bits(x);
+    /// let _: f32 = f32::from_bits(1_u32);
     /// ```
     pub TRANSMUTE_INT_TO_FLOAT,
     complexity,
@@ -195,7 +208,7 @@ declare_clippy_lint! {
     ///     let _: &f32 = std::mem::transmute(&1u32);
     /// }
     /// // These can be respectively written:
-    /// let _ = ptr as *const f32
+    /// let _ = ptr as *const f32;
     /// let _ = unsafe{ &*(&1u32 as *const u32 as *const f32) };
     /// ```
     pub TRANSMUTE_PTR_TO_PTR,
diff --git a/clippy_lints/src/types.rs b/clippy_lints/src/types.rs
index 549ba56eec2..838ec76704d 100644
--- a/clippy_lints/src/types.rs
+++ b/clippy_lints/src/types.rs
@@ -557,7 +557,7 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// foo({
     ///     let a = bar();
     ///     baz(a);
@@ -775,7 +775,7 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// let _ = 2i32 as i32
+    /// let _ = 2i32 as i32;
     /// ```
     pub UNNECESSARY_CAST,
     complexity,
@@ -1295,6 +1295,7 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
+    /// # use std::rc::Rc;
     /// struct Foo {
     ///     inner: Rc<Vec<Vec<Box<(u32, u32, u32, u32)>>>>,
     /// }
@@ -1458,13 +1459,13 @@ declare_clippy_lint! {
     /// **Known problems:** None.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// 'x' as u8
     /// ```
     ///
     /// A better version, using the byte literal:
     ///
-    /// ```rust
+    /// ```rust,ignore
     /// b'x'
     /// ```
     pub CHAR_LIT_AS_U8,
diff --git a/clippy_lints/src/utils/author.rs b/clippy_lints/src/utils/author.rs
index f419338097d..811bdce18e8 100644
--- a/clippy_lints/src/utils/author.rs
+++ b/clippy_lints/src/utils/author.rs
@@ -15,7 +15,7 @@ declare_clippy_lint! {
     /// **What it does:** Generates clippy code that detects the offending pattern
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// // ./tests/ui/my_lint.rs
     /// fn foo() {
     ///     // detect the following pattern
@@ -24,13 +24,14 @@ declare_clippy_lint! {
     ///         // but ignore everything from here on
     ///         #![clippy::author = "ignore"]
     ///     }
+    ///     ()
     /// }
     /// ```
     ///
     /// Running `TESTNAME=ui/my_lint cargo uitest` will produce
     /// a `./tests/ui/new_lint.stdout` file with the generated code:
     ///
-    /// ```rust
+    /// ```rust,ignore
     /// // ./tests/ui/new_lint.stdout
     /// if_chain! {
     ///     if let ExprKind::If(ref cond, ref then, None) = item.node,
diff --git a/clippy_lints/src/utils/inspector.rs b/clippy_lints/src/utils/inspector.rs
index ea169481ac6..48dc98c0556 100644
--- a/clippy_lints/src/utils/inspector.rs
+++ b/clippy_lints/src/utils/inspector.rs
@@ -13,14 +13,14 @@ declare_clippy_lint! {
     /// attribute
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// #[clippy::dump]
     /// extern crate foo;
     /// ```
     ///
     /// prints
     ///
-    /// ```
+    /// ```text
     /// item `foo`
     /// visibility inherited from outer item
     /// extern crate dylib source: "/path/to/foo.so"
diff --git a/clippy_lints/src/utils/internal_lints.rs b/clippy_lints/src/utils/internal_lints.rs
index 6393bf2add4..0dcac112184 100644
--- a/clippy_lints/src/utils/internal_lints.rs
+++ b/clippy_lints/src/utils/internal_lints.rs
@@ -38,7 +38,7 @@ declare_clippy_lint! {
     /// `declare_lint_pass!`, `impl_lint_pass!`, and `lint_array!` macros.
     ///
     /// **Example:**
-    /// ```rust
+    /// ```rust,ignore
     /// declare_lint! { pub LINT_1, ... }
     /// declare_lint! { pub LINT_2, ... }
     /// declare_lint! { pub FORGOTTEN_LINT, ... }
@@ -62,12 +62,12 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// Bad:
-    /// ```rust
+    /// ```rust,ignore
     /// cx.span_lint(LINT_NAME, "message");
     /// ```
     ///
     /// Good:
-    /// ```rust
+    /// ```rust,ignore
     /// utils::span_lint(cx, LINT_NAME, "message");
     /// ```
     pub COMPILER_LINT_FUNCTIONS,
@@ -85,12 +85,12 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// Bad:
-    /// ```rust
+    /// ```rust,ignore
     /// expr.span.ctxt().outer().expn_info()
     /// ```
     ///
     /// Good:
-    /// ```rust
+    /// ```rust,ignore
     /// expr.span.ctxt().outer_expn_info()
     /// ```
     pub OUTER_EXPN_EXPN_INFO,
diff --git a/clippy_lints/src/zero_div_zero.rs b/clippy_lints/src/zero_div_zero.rs
index 094cb627dc3..1c4c54f2626 100644
--- a/clippy_lints/src/zero_div_zero.rs
+++ b/clippy_lints/src/zero_div_zero.rs
@@ -15,7 +15,7 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
-    /// 0.0f32 / 0.0
+    /// 0.0f32 / 0.0;
     /// ```
     pub ZERO_DIVIDED_BY_ZERO,
     complexity,