Merge commit '70c0f90453701e7d6d9b99aaa1fc6a765937b736' into clippyup

37 files changed, 644 insertions, 22 deletions

diff --git a/src/tools/clippy/tests/compile-test.rs b/src/tools/clippy/tests/compile-test.rs
index 94f5e616cac..c0b40add109 100644
--- a/src/tools/clippy/tests/compile-test.rs
+++ b/src/tools/clippy/tests/compile-test.rs
@@ -214,6 +214,7 @@ fn run_ui_cargo(config: &mut compiletest::Config) {
                         Some("main.rs") => {},
                         _ => continue,
                     }
+                    set_var("CLIPPY_CONF_DIR", case.path());
                     let paths = compiletest::common::TestPaths {
                         file: file_path,
                         base: config.src_base.clone(),
@@ -241,9 +242,11 @@ fn run_ui_cargo(config: &mut compiletest::Config) {
     let tests = compiletest::make_tests(&config);
 
     let current_dir = env::current_dir().unwrap();
+    let conf_dir = var("CLIPPY_CONF_DIR").unwrap_or_default();
     let filter = env::var("TESTNAME").ok();
     let res = run_tests(&config, &filter, tests);
     env::set_current_dir(current_dir).unwrap();
+    set_var("CLIPPY_CONF_DIR", conf_dir);
 
     match res {
         Ok(true) => {},
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail/clippy.toml b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail/clippy.toml
new file mode 100644
index 00000000000..de4f04b24fc
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail/clippy.toml
@@ -0,0 +1 @@
+cargo-ignore-publish = true
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish/Cargo.toml b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish/Cargo.toml
new file mode 100644
index 00000000000..7595696353c
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "cargo_common_metadata"
+version = "0.1.0"
+publish = ["some-registry-name"]
+
+[workspace]
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish/src/main.rs b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish/src/main.rs
new file mode 100644
index 00000000000..27841e18aa9
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish/src/main.rs
@@ -0,0 +1,4 @@
+// compile-flags: --crate-name=cargo_common_metadata
+#![warn(clippy::cargo_common_metadata)]
+
+fn main() {}
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish/src/main.stderr b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish/src/main.stderr
new file mode 100644
index 00000000000..c8ae6c820df
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish/src/main.stderr
@@ -0,0 +1,18 @@
+error: package `cargo_common_metadata` is missing `package.authors` metadata
+   |
+   = note: `-D clippy::cargo-common-metadata` implied by `-D warnings`
+
+error: package `cargo_common_metadata` is missing `package.description` metadata
+
+error: package `cargo_common_metadata` is missing `either package.license or package.license_file` metadata
+
+error: package `cargo_common_metadata` is missing `package.repository` metadata
+
+error: package `cargo_common_metadata` is missing `package.readme` metadata
+
+error: package `cargo_common_metadata` is missing `package.keywords` metadata
+
+error: package `cargo_common_metadata` is missing `package.categories` metadata
+
+error: aborting due to 7 previous errors
+
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish_true/Cargo.toml b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish_true/Cargo.toml
new file mode 100644
index 00000000000..7e5b88383cc
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish_true/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "cargo_common_metadata"
+version = "0.1.0"
+publish = true
+
+[workspace]
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish_true/src/main.rs b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish_true/src/main.rs
new file mode 100644
index 00000000000..27841e18aa9
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish_true/src/main.rs
@@ -0,0 +1,4 @@
+// compile-flags: --crate-name=cargo_common_metadata
+#![warn(clippy::cargo_common_metadata)]
+
+fn main() {}
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish_true/src/main.stderr b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish_true/src/main.stderr
new file mode 100644
index 00000000000..c8ae6c820df
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/fail_publish_true/src/main.stderr
@@ -0,0 +1,18 @@
+error: package `cargo_common_metadata` is missing `package.authors` metadata
+   |
+   = note: `-D clippy::cargo-common-metadata` implied by `-D warnings`
+
+error: package `cargo_common_metadata` is missing `package.description` metadata
+
+error: package `cargo_common_metadata` is missing `either package.license or package.license_file` metadata
+
+error: package `cargo_common_metadata` is missing `package.repository` metadata
+
+error: package `cargo_common_metadata` is missing `package.readme` metadata
+
+error: package `cargo_common_metadata` is missing `package.keywords` metadata
+
+error: package `cargo_common_metadata` is missing `package.categories` metadata
+
+error: aborting due to 7 previous errors
+
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass/clippy.toml b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass/clippy.toml
new file mode 100644
index 00000000000..de4f04b24fc
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass/clippy.toml
@@ -0,0 +1 @@
+cargo-ignore-publish = true
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_empty/Cargo.toml b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_empty/Cargo.toml
new file mode 100644
index 00000000000..0a879c99b5b
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_empty/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "cargo_common_metadata"
+version = "0.1.0"
+publish = []
+
+[workspace]
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_empty/src/main.rs b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_empty/src/main.rs
new file mode 100644
index 00000000000..27841e18aa9
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_empty/src/main.rs
@@ -0,0 +1,4 @@
+// compile-flags: --crate-name=cargo_common_metadata
+#![warn(clippy::cargo_common_metadata)]
+
+fn main() {}
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_false/Cargo.toml b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_false/Cargo.toml
new file mode 100644
index 00000000000..ae0a6032996
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_false/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "cargo_common_metadata"
+version = "0.1.0"
+publish = false
+
+[workspace]
diff --git a/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_false/src/main.rs b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_false/src/main.rs
new file mode 100644
index 00000000000..27841e18aa9
--- /dev/null
+++ b/src/tools/clippy/tests/ui-cargo/cargo_common_metadata/pass_publish_false/src/main.rs
@@ -0,0 +1,4 @@
+// compile-flags: --crate-name=cargo_common_metadata
+#![warn(clippy::cargo_common_metadata)]
+
+fn main() {}
diff --git a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/clippy.toml b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/clippy.toml
index a1f515e443d..c0df3b6e8af 100644
--- a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/clippy.toml
+++ b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/clippy.toml
@@ -1 +1 @@
-disallowed-methods = ["core::iter::traits::iterator::Iterator::sum", "regex::re_unicode::Regex::is_match"]
+disallowed-methods = ["core::iter::traits::iterator::Iterator::sum", "regex::re_unicode::Regex::is_match", "regex::re_unicode::Regex::new"]
diff --git a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.rs b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.rs
index 3d3f0729abd..1901a99377e 100644
--- a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.rs
+++ b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.rs
@@ -4,10 +4,9 @@ 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");
 
+    let a = vec![1, 2, 3, 4];
     a.iter().sum::<i32>();
 }
diff --git a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr
index ed91b5a6796..2b628c67fa7 100644
--- a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr
+++ b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr
@@ -1,16 +1,22 @@
+error: use of a disallowed method `regex::re_unicode::Regex::new`
+  --> $DIR/conf_disallowed_method.rs:7:14
+   |
+LL |     let re = Regex::new(r"ab.*c").unwrap();
+   |              ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::disallowed-method` implied by `-D warnings`
+
 error: use of a disallowed method `regex::re_unicode::Regex::is_match`
-  --> $DIR/conf_disallowed_method.rs:10:5
+  --> $DIR/conf_disallowed_method.rs:8:5
    |
 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
+  --> $DIR/conf_disallowed_method.rs:11:5
    |
 LL |     a.iter().sum::<i32>();
    |     ^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
diff --git a/src/tools/clippy/tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr b/src/tools/clippy/tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr
index 7b3c476461d..7ccd0b54845 100644
--- a/src/tools/clippy/tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr
+++ b/src/tools/clippy/tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr
@@ -1,4 +1,4 @@
-error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `msrv`, `blacklisted-names`, `cognitive-complexity-threshold`, `cyclomatic-complexity-threshold`, `doc-valid-idents`, `too-many-arguments-threshold`, `type-complexity-threshold`, `single-char-binding-names-threshold`, `too-large-for-stack`, `enum-variant-name-threshold`, `enum-variant-size-threshold`, `verbose-bit-mask-threshold`, `literal-representation-threshold`, `trivial-copy-size-limit`, `pass-by-value-size-limit`, `too-many-lines-threshold`, `array-size-threshold`, `vec-box-size-threshold`, `max-trait-bounds`, `max-struct-bools`, `max-fn-params-bools`, `warn-on-all-wildcard-imports`, `disallowed-methods`, `unreadable-literal-lint-fractions`, `third-party` at line 5 column 1
+error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `msrv`, `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`, `pass-by-value-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`, `unreadable-literal-lint-fractions`, `cargo-ignore-publish`, `third-party` at line 5 column 1
 
 error: aborting due to previous error
 
diff --git a/src/tools/clippy/tests/ui/bytes_nth.fixed b/src/tools/clippy/tests/ui/bytes_nth.fixed
new file mode 100644
index 00000000000..bf68a7bbbf1
--- /dev/null
+++ b/src/tools/clippy/tests/ui/bytes_nth.fixed
@@ -0,0 +1,11 @@
+// run-rustfix
+
+#![allow(clippy::unnecessary_operation)]
+#![warn(clippy::bytes_nth)]
+
+fn main() {
+    let s = String::from("String");
+    s.as_bytes().get(3);
+    &s.as_bytes().get(3);
+    s[..].as_bytes().get(3);
+}
diff --git a/src/tools/clippy/tests/ui/bytes_nth.rs b/src/tools/clippy/tests/ui/bytes_nth.rs
new file mode 100644
index 00000000000..629812cc02c
--- /dev/null
+++ b/src/tools/clippy/tests/ui/bytes_nth.rs
@@ -0,0 +1,11 @@
+// run-rustfix
+
+#![allow(clippy::unnecessary_operation)]
+#![warn(clippy::bytes_nth)]
+
+fn main() {
+    let s = String::from("String");
+    s.bytes().nth(3);
+    &s.bytes().nth(3);
+    s[..].bytes().nth(3);
+}
diff --git a/src/tools/clippy/tests/ui/bytes_nth.stderr b/src/tools/clippy/tests/ui/bytes_nth.stderr
new file mode 100644
index 00000000000..9a5742928cd
--- /dev/null
+++ b/src/tools/clippy/tests/ui/bytes_nth.stderr
@@ -0,0 +1,22 @@
+error: called `.byte().nth()` on a `String`
+  --> $DIR/bytes_nth.rs:8:5
+   |
+LL |     s.bytes().nth(3);
+   |     ^^^^^^^^^^^^^^^^ help: try: `s.as_bytes().get(3)`
+   |
+   = note: `-D clippy::bytes-nth` implied by `-D warnings`
+
+error: called `.byte().nth()` on a `String`
+  --> $DIR/bytes_nth.rs:9:6
+   |
+LL |     &s.bytes().nth(3);
+   |      ^^^^^^^^^^^^^^^^ help: try: `s.as_bytes().get(3)`
+
+error: called `.byte().nth()` on a `str`
+  --> $DIR/bytes_nth.rs:10:5
+   |
+LL |     s[..].bytes().nth(3);
+   |     ^^^^^^^^^^^^^^^^^^^^ help: try: `s[..].as_bytes().get(3)`
+
+error: aborting due to 3 previous errors
+
diff --git a/src/tools/clippy/tests/ui/collapsible_match.rs b/src/tools/clippy/tests/ui/collapsible_match.rs
index a83e6c77b12..3294da7e814 100644
--- a/src/tools/clippy/tests/ui/collapsible_match.rs
+++ b/src/tools/clippy/tests/ui/collapsible_match.rs
@@ -224,6 +224,14 @@ fn negative_cases(res_opt: Result<Option<u32>, String>, res_res: Result<Result<u
         },
         _ => return,
     }
+    if let Ok(val) = res_opt {
+        if let Some(n) = val {
+            let _ = || {
+                // usage in closure
+                println!("{:?}", val);
+            };
+        }
+    }
 }
 
 fn make<T>() -> T {
diff --git a/src/tools/clippy/tests/ui/filter_map_identity.fixed b/src/tools/clippy/tests/ui/filter_map_identity.fixed
new file mode 100644
index 00000000000..23ce28d8e9b
--- /dev/null
+++ b/src/tools/clippy/tests/ui/filter_map_identity.fixed
@@ -0,0 +1,16 @@
+// run-rustfix
+
+#![allow(unused_imports)]
+#![warn(clippy::filter_map_identity)]
+
+fn main() {
+    let iterator = vec![Some(1), None, Some(2)].into_iter();
+    let _ = iterator.flatten();
+
+    let iterator = vec![Some(1), None, Some(2)].into_iter();
+    let _ = iterator.flatten();
+
+    use std::convert::identity;
+    let iterator = vec![Some(1), None, Some(2)].into_iter();
+    let _ = iterator.flatten();
+}
diff --git a/src/tools/clippy/tests/ui/filter_map_identity.rs b/src/tools/clippy/tests/ui/filter_map_identity.rs
new file mode 100644
index 00000000000..e698df13eea
--- /dev/null
+++ b/src/tools/clippy/tests/ui/filter_map_identity.rs
@@ -0,0 +1,16 @@
+// run-rustfix
+
+#![allow(unused_imports)]
+#![warn(clippy::filter_map_identity)]
+
+fn main() {
+    let iterator = vec![Some(1), None, Some(2)].into_iter();
+    let _ = iterator.filter_map(|x| x);
+
+    let iterator = vec![Some(1), None, Some(2)].into_iter();
+    let _ = iterator.filter_map(std::convert::identity);
+
+    use std::convert::identity;
+    let iterator = vec![Some(1), None, Some(2)].into_iter();
+    let _ = iterator.filter_map(identity);
+}
diff --git a/src/tools/clippy/tests/ui/filter_map_identity.stderr b/src/tools/clippy/tests/ui/filter_map_identity.stderr
new file mode 100644
index 00000000000..596a6320608
--- /dev/null
+++ b/src/tools/clippy/tests/ui/filter_map_identity.stderr
@@ -0,0 +1,22 @@
+error: called `filter_map(|x| x)` on an `Iterator`
+  --> $DIR/filter_map_identity.rs:8:22
+   |
+LL |     let _ = iterator.filter_map(|x| x);
+   |                      ^^^^^^^^^^^^^^^^^ help: try: `flatten()`
+   |
+   = note: `-D clippy::filter-map-identity` implied by `-D warnings`
+
+error: called `filter_map(std::convert::identity)` on an `Iterator`
+  --> $DIR/filter_map_identity.rs:11:22
+   |
+LL |     let _ = iterator.filter_map(std::convert::identity);
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
+
+error: called `filter_map(std::convert::identity)` on an `Iterator`
+  --> $DIR/filter_map_identity.rs:15:22
+   |
+LL |     let _ = iterator.filter_map(identity);
+   |                      ^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
+
+error: aborting due to 3 previous errors
+
diff --git a/src/tools/clippy/tests/ui/unnecessary_flat_map.fixed b/src/tools/clippy/tests/ui/flat_map_identity.fixed
index dfe3bd47e13..dfe3bd47e13 100644
--- a/src/tools/clippy/tests/ui/unnecessary_flat_map.fixed
+++ b/src/tools/clippy/tests/ui/flat_map_identity.fixed
diff --git a/src/tools/clippy/tests/ui/unnecessary_flat_map.rs b/src/tools/clippy/tests/ui/flat_map_identity.rs
index 393b9569255..393b9569255 100644
--- a/src/tools/clippy/tests/ui/unnecessary_flat_map.rs
+++ b/src/tools/clippy/tests/ui/flat_map_identity.rs
diff --git a/src/tools/clippy/tests/ui/unnecessary_flat_map.stderr b/src/tools/clippy/tests/ui/flat_map_identity.stderr
index a1cd5745e49..e4686ae5a54 100644
--- a/src/tools/clippy/tests/ui/unnecessary_flat_map.stderr
+++ b/src/tools/clippy/tests/ui/flat_map_identity.stderr
@@ -1,5 +1,5 @@
 error: called `flat_map(|x| x)` on an `Iterator`
-  --> $DIR/unnecessary_flat_map.rs:10:22
+  --> $DIR/flat_map_identity.rs:10:22
    |
 LL |     let _ = iterator.flat_map(|x| x);
    |                      ^^^^^^^^^^^^^^^ help: try: `flatten()`
@@ -7,7 +7,7 @@ LL |     let _ = iterator.flat_map(|x| x);
    = note: `-D clippy::flat-map-identity` implied by `-D warnings`
 
 error: called `flat_map(std::convert::identity)` on an `Iterator`
-  --> $DIR/unnecessary_flat_map.rs:13:22
+  --> $DIR/flat_map_identity.rs:13:22
    |
 LL |     let _ = iterator.flat_map(convert::identity);
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
diff --git a/src/tools/clippy/tests/ui/from_iter_instead_of_collect.fixed b/src/tools/clippy/tests/ui/from_iter_instead_of_collect.fixed
new file mode 100644
index 00000000000..b5f548810e6
--- /dev/null
+++ b/src/tools/clippy/tests/ui/from_iter_instead_of_collect.fixed
@@ -0,0 +1,48 @@
+// run-rustfix
+
+#![warn(clippy::from_iter_instead_of_collect)]
+#![allow(unused_imports)]
+
+use std::collections::{BTreeMap, BTreeSet, HashMap, VecDeque};
+use std::iter::FromIterator;
+
+fn main() {
+    let iter_expr = std::iter::repeat(5).take(5);
+    let _ = iter_expr.collect::<Vec<_>>();
+
+    let _ = vec![5, 5, 5, 5].iter().enumerate().collect::<HashMap<usize, &i8>>();
+
+    Vec::from_iter(vec![42u32]);
+
+    let a = vec![0, 1, 2];
+    assert_eq!(a, (0..3).collect::<Vec<_>>());
+    assert_eq!(a, (0..3).collect::<Vec<i32>>());
+
+    let mut b = (0..3).collect::<VecDeque<_>>();
+    b.push_back(4);
+
+    let mut b = (0..3).collect::<VecDeque<i32>>();
+    b.push_back(4);
+
+    {
+        use std::collections;
+        let mut b = (0..3).collect::<collections::VecDeque<i32>>();
+        b.push_back(4);
+    }
+
+    let values = [(0, 'a'), (1, 'b'), (2, 'c'), (3, 'd')];
+    let bm = values.iter().cloned().collect::<BTreeMap<_, _>>();
+    let mut bar = bm.range(0..2).collect::<BTreeMap<_, _>>();
+    bar.insert(&4, &'e');
+
+    let mut bts = (0..3).collect::<BTreeSet<_>>();
+    bts.insert(2);
+    {
+        use std::collections;
+        let _ = (0..3).collect::<collections::BTreeSet<_>>();
+        let _ = (0..3).collect::<collections::BTreeSet<u32>>();
+    }
+
+    for _i in [1, 2, 3].iter().collect::<Vec<_>>() {}
+    for _i in [1, 2, 3].iter().collect::<Vec<&i32>>() {}
+}
diff --git a/src/tools/clippy/tests/ui/from_iter_instead_of_collect.rs b/src/tools/clippy/tests/ui/from_iter_instead_of_collect.rs
index 045eb3133d3..b842b5451d1 100644
--- a/src/tools/clippy/tests/ui/from_iter_instead_of_collect.rs
+++ b/src/tools/clippy/tests/ui/from_iter_instead_of_collect.rs
@@ -1,13 +1,48 @@
+// run-rustfix
+
 #![warn(clippy::from_iter_instead_of_collect)]
+#![allow(unused_imports)]
 
-use std::collections::HashMap;
+use std::collections::{BTreeMap, BTreeSet, HashMap, VecDeque};
 use std::iter::FromIterator;
 
 fn main() {
     let iter_expr = std::iter::repeat(5).take(5);
-    Vec::from_iter(iter_expr);
+    let _ = Vec::from_iter(iter_expr);
 
-    HashMap::<usize, &i8>::from_iter(vec![5, 5, 5, 5].iter().enumerate());
+    let _ = HashMap::<usize, &i8>::from_iter(vec![5, 5, 5, 5].iter().enumerate());
 
     Vec::from_iter(vec![42u32]);
+
+    let a = vec![0, 1, 2];
+    assert_eq!(a, Vec::from_iter(0..3));
+    assert_eq!(a, Vec::<i32>::from_iter(0..3));
+
+    let mut b = VecDeque::from_iter(0..3);
+    b.push_back(4);
+
+    let mut b = VecDeque::<i32>::from_iter(0..3);
+    b.push_back(4);
+
+    {
+        use std::collections;
+        let mut b = collections::VecDeque::<i32>::from_iter(0..3);
+        b.push_back(4);
+    }
+
+    let values = [(0, 'a'), (1, 'b'), (2, 'c'), (3, 'd')];
+    let bm = BTreeMap::from_iter(values.iter().cloned());
+    let mut bar = BTreeMap::from_iter(bm.range(0..2));
+    bar.insert(&4, &'e');
+
+    let mut bts = BTreeSet::from_iter(0..3);
+    bts.insert(2);
+    {
+        use std::collections;
+        let _ = collections::BTreeSet::from_iter(0..3);
+        let _ = collections::BTreeSet::<u32>::from_iter(0..3);
+    }
+
+    for _i in Vec::from_iter([1, 2, 3].iter()) {}
+    for _i in Vec::<&i32>::from_iter([1, 2, 3].iter()) {}
 }
diff --git a/src/tools/clippy/tests/ui/from_iter_instead_of_collect.stderr b/src/tools/clippy/tests/ui/from_iter_instead_of_collect.stderr
index 46bdc2f4e19..434734c9a21 100644
--- a/src/tools/clippy/tests/ui/from_iter_instead_of_collect.stderr
+++ b/src/tools/clippy/tests/ui/from_iter_instead_of_collect.stderr
@@ -1,16 +1,88 @@
 error: usage of `FromIterator::from_iter`
-  --> $DIR/from_iter_instead_of_collect.rs:8:5
+  --> $DIR/from_iter_instead_of_collect.rs:11:13
    |
-LL |     Vec::from_iter(iter_expr);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `iter_expr.collect()`
+LL |     let _ = Vec::from_iter(iter_expr);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `iter_expr.collect::<Vec<_>>()`
    |
    = note: `-D clippy::from-iter-instead-of-collect` implied by `-D warnings`
 
 error: usage of `FromIterator::from_iter`
-  --> $DIR/from_iter_instead_of_collect.rs:10:5
+  --> $DIR/from_iter_instead_of_collect.rs:13:13
    |
-LL |     HashMap::<usize, &i8>::from_iter(vec![5, 5, 5, 5].iter().enumerate());
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `vec![5, 5, 5, 5].iter().enumerate().collect()`
+LL |     let _ = HashMap::<usize, &i8>::from_iter(vec![5, 5, 5, 5].iter().enumerate());
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `vec![5, 5, 5, 5].iter().enumerate().collect::<HashMap<usize, &i8>>()`
 
-error: aborting due to 2 previous errors
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:18:19
+   |
+LL |     assert_eq!(a, Vec::from_iter(0..3));
+   |                   ^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `(0..3).collect::<Vec<_>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:19:19
+   |
+LL |     assert_eq!(a, Vec::<i32>::from_iter(0..3));
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `(0..3).collect::<Vec<i32>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:21:17
+   |
+LL |     let mut b = VecDeque::from_iter(0..3);
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `(0..3).collect::<VecDeque<_>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:24:17
+   |
+LL |     let mut b = VecDeque::<i32>::from_iter(0..3);
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `(0..3).collect::<VecDeque<i32>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:29:21
+   |
+LL |         let mut b = collections::VecDeque::<i32>::from_iter(0..3);
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `(0..3).collect::<collections::VecDeque<i32>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:34:14
+   |
+LL |     let bm = BTreeMap::from_iter(values.iter().cloned());
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `values.iter().cloned().collect::<BTreeMap<_, _>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:35:19
+   |
+LL |     let mut bar = BTreeMap::from_iter(bm.range(0..2));
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `bm.range(0..2).collect::<BTreeMap<_, _>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:38:19
+   |
+LL |     let mut bts = BTreeSet::from_iter(0..3);
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `(0..3).collect::<BTreeSet<_>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:42:17
+   |
+LL |         let _ = collections::BTreeSet::from_iter(0..3);
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `(0..3).collect::<collections::BTreeSet<_>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:43:17
+   |
+LL |         let _ = collections::BTreeSet::<u32>::from_iter(0..3);
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `(0..3).collect::<collections::BTreeSet<u32>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:46:15
+   |
+LL |     for _i in Vec::from_iter([1, 2, 3].iter()) {}
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `[1, 2, 3].iter().collect::<Vec<_>>()`
+
+error: usage of `FromIterator::from_iter`
+  --> $DIR/from_iter_instead_of_collect.rs:47:15
+   |
+LL |     for _i in Vec::<&i32>::from_iter([1, 2, 3].iter()) {}
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `[1, 2, 3].iter().collect::<Vec<&i32>>()`
+
+error: aborting due to 14 previous errors
 
diff --git a/src/tools/clippy/tests/ui/let_underscore_drop.rs b/src/tools/clippy/tests/ui/let_underscore_drop.rs
index 98593edb9c5..50744f81c3c 100644
--- a/src/tools/clippy/tests/ui/let_underscore_drop.rs
+++ b/src/tools/clippy/tests/ui/let_underscore_drop.rs
@@ -16,4 +16,12 @@ fn main() {
     let _ = Box::new(());
     let _ = Droppable;
     let _ = Some(Droppable);
+
+    // no lint for reference
+    let _ = droppable_ref();
+}
+
+#[must_use]
+fn droppable_ref() -> &'static mut Droppable {
+    unimplemented!()
 }
diff --git a/src/tools/clippy/tests/ui/manual_flatten.rs b/src/tools/clippy/tests/ui/manual_flatten.rs
new file mode 100644
index 00000000000..cff68eca933
--- /dev/null
+++ b/src/tools/clippy/tests/ui/manual_flatten.rs
@@ -0,0 +1,76 @@
+#![warn(clippy::manual_flatten)]
+
+fn main() {
+    // Test for loop over implicitly adjusted `Iterator` with `if let` expression
+    let x = vec![Some(1), Some(2), Some(3)];
+    for n in x {
+        if let Some(y) = n {
+            println!("{}", y);
+        }
+    }
+
+    // Test for loop over implicitly implicitly adjusted `Iterator` with `if let` statement
+    let y: Vec<Result<i32, i32>> = vec![];
+    for n in y.clone() {
+        if let Ok(n) = n {
+            println!("{}", n);
+        };
+    }
+
+    // Test for loop over by reference
+    for n in &y {
+        if let Ok(n) = n {
+            println!("{}", n);
+        }
+    }
+
+    // Test for loop over an implicit reference
+    // Note: if `clippy::manual_flatten` is made autofixable, this case will
+    // lead to a follow-up lint `clippy::into_iter_on_ref`
+    let z = &y;
+    for n in z {
+        if let Ok(n) = n {
+            println!("{}", n);
+        }
+    }
+
+    // Test for loop over `Iterator` with `if let` expression
+    let z = vec![Some(1), Some(2), Some(3)];
+    let z = z.iter();
+    for n in z {
+        if let Some(m) = n {
+            println!("{}", m);
+        }
+    }
+
+    // Using the `None` variant should not trigger the lint
+    // Note: for an autofixable suggestion, the binding in the for loop has to take the
+    // name of the binding in the `if let`
+    let z = vec![Some(1), Some(2), Some(3)];
+    for n in z {
+        if n.is_none() {
+            println!("Nada.");
+        }
+    }
+
+    // Using the `Err` variant should not trigger the lint
+    for n in y.clone() {
+        if let Err(e) = n {
+            println!("Oops: {}!", e);
+        }
+    }
+
+    // Having an else clause should not trigger the lint
+    for n in y.clone() {
+        if let Ok(n) = n {
+            println!("{}", n);
+        } else {
+            println!("Oops!");
+        }
+    }
+
+    // Using manual flatten should not trigger the lint
+    for n in vec![Some(1), Some(2), Some(3)].iter().flatten() {
+        println!("{}", n);
+    }
+}
diff --git a/src/tools/clippy/tests/ui/manual_flatten.stderr b/src/tools/clippy/tests/ui/manual_flatten.stderr
new file mode 100644
index 00000000000..855dd9130e2
--- /dev/null
+++ b/src/tools/clippy/tests/ui/manual_flatten.stderr
@@ -0,0 +1,108 @@
+error: unnecessary `if let` since only the `Some` variant of the iterator element is used
+  --> $DIR/manual_flatten.rs:6:5
+   |
+LL |       for n in x {
+   |       ^        - help: try: `x.into_iter().flatten()`
+   |  _____|
+   | |
+LL | |         if let Some(y) = n {
+LL | |             println!("{}", y);
+LL | |         }
+LL | |     }
+   | |_____^
+   |
+   = note: `-D clippy::manual-flatten` implied by `-D warnings`
+help: ...and remove the `if let` statement in the for loop
+  --> $DIR/manual_flatten.rs:7:9
+   |
+LL | /         if let Some(y) = n {
+LL | |             println!("{}", y);
+LL | |         }
+   | |_________^
+
+error: unnecessary `if let` since only the `Ok` variant of the iterator element is used
+  --> $DIR/manual_flatten.rs:14:5
+   |
+LL |       for n in y.clone() {
+   |       ^        --------- help: try: `y.clone().into_iter().flatten()`
+   |  _____|
+   | |
+LL | |         if let Ok(n) = n {
+LL | |             println!("{}", n);
+LL | |         };
+LL | |     }
+   | |_____^
+   |
+help: ...and remove the `if let` statement in the for loop
+  --> $DIR/manual_flatten.rs:15:9
+   |
+LL | /         if let Ok(n) = n {
+LL | |             println!("{}", n);
+LL | |         };
+   | |_________^
+
+error: unnecessary `if let` since only the `Ok` variant of the iterator element is used
+  --> $DIR/manual_flatten.rs:21:5
+   |
+LL |       for n in &y {
+   |       ^        -- help: try: `y.iter().flatten()`
+   |  _____|
+   | |
+LL | |         if let Ok(n) = n {
+LL | |             println!("{}", n);
+LL | |         }
+LL | |     }
+   | |_____^
+   |
+help: ...and remove the `if let` statement in the for loop
+  --> $DIR/manual_flatten.rs:22:9
+   |
+LL | /         if let Ok(n) = n {
+LL | |             println!("{}", n);
+LL | |         }
+   | |_________^
+
+error: unnecessary `if let` since only the `Ok` variant of the iterator element is used
+  --> $DIR/manual_flatten.rs:31:5
+   |
+LL |       for n in z {
+   |       ^        - help: try: `z.into_iter().flatten()`
+   |  _____|
+   | |
+LL | |         if let Ok(n) = n {
+LL | |             println!("{}", n);
+LL | |         }
+LL | |     }
+   | |_____^
+   |
+help: ...and remove the `if let` statement in the for loop
+  --> $DIR/manual_flatten.rs:32:9
+   |
+LL | /         if let Ok(n) = n {
+LL | |             println!("{}", n);
+LL | |         }
+   | |_________^
+
+error: unnecessary `if let` since only the `Some` variant of the iterator element is used
+  --> $DIR/manual_flatten.rs:40:5
+   |
+LL |       for n in z {
+   |       ^        - help: try: `z.flatten()`
+   |  _____|
+   | |
+LL | |         if let Some(m) = n {
+LL | |             println!("{}", m);
+LL | |         }
+LL | |     }
+   | |_____^
+   |
+help: ...and remove the `if let` statement in the for loop
+  --> $DIR/manual_flatten.rs:41:9
+   |
+LL | /         if let Some(m) = n {
+LL | |             println!("{}", m);
+LL | |         }
+   | |_________^
+
+error: aborting due to 5 previous errors
+
diff --git a/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.rs b/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.rs
new file mode 100644
index 00000000000..0abe2cca267
--- /dev/null
+++ b/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.rs
@@ -0,0 +1,55 @@
+#![warn(clippy::semicolon_if_nothing_returned)]
+#![feature(label_break_value)]
+
+fn get_unit() {}
+
+// the functions below trigger the lint
+fn main() {
+    println!("Hello")
+}
+
+fn hello() {
+    get_unit()
+}
+
+fn basic101(x: i32) {
+    let y: i32;
+    y = x + 1
+}
+
+// this is fine
+fn print_sum(a: i32, b: i32) {
+    println!("{}", a + b);
+    assert_eq!(true, false);
+}
+
+fn foo(x: i32) {
+    let y: i32;
+    if x < 1 {
+        y = 4;
+    } else {
+        y = 5;
+    }
+}
+
+fn bar(x: i32) {
+    let y: i32;
+    match x {
+        1 => y = 4,
+        _ => y = 32,
+    }
+}
+
+fn foobar(x: i32) {
+    let y: i32;
+    'label: {
+        y = x + 1;
+    }
+}
+
+fn loop_test(x: i32) {
+    let y: i32;
+    for &ext in &["stdout", "stderr", "fixed"] {
+        println!("{}", ext);
+    }
+}
diff --git a/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.stderr b/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.stderr
new file mode 100644
index 00000000000..b73f8967538
--- /dev/null
+++ b/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.stderr
@@ -0,0 +1,22 @@
+error: consider adding a `;` to the last statement for consistent formatting
+  --> $DIR/semicolon_if_nothing_returned.rs:8:5
+   |
+LL |     println!("Hello")
+   |     ^^^^^^^^^^^^^^^^^ help: add a `;` here: `println!("Hello");`
+   |
+   = note: `-D clippy::semicolon-if-nothing-returned` implied by `-D warnings`
+
+error: consider adding a `;` to the last statement for consistent formatting
+  --> $DIR/semicolon_if_nothing_returned.rs:12:5
+   |
+LL |     get_unit()
+   |     ^^^^^^^^^^ help: add a `;` here: `get_unit();`
+
+error: consider adding a `;` to the last statement for consistent formatting
+  --> $DIR/semicolon_if_nothing_returned.rs:17:5
+   |
+LL |     y = x + 1
+   |     ^^^^^^^^^ help: add a `;` here: `y = x + 1;`
+
+error: aborting due to 3 previous errors
+
diff --git a/src/tools/clippy/tests/ui/zero_div_zero.rs b/src/tools/clippy/tests/ui/zero_div_zero.rs
index 09db130a764..ed3a9208fc3 100644
--- a/src/tools/clippy/tests/ui/zero_div_zero.rs
+++ b/src/tools/clippy/tests/ui/zero_div_zero.rs
@@ -7,7 +7,7 @@ fn main() {
     let one_more_f64_nan = 0.0f64 / 0.0f64;
     let zero = 0.0;
     let other_zero = 0.0;
-    let other_nan = zero / other_zero; // fine - this lint doesn't propegate constants.
+    let other_nan = zero / other_zero; // fine - this lint doesn't propagate constants.
     let not_nan = 2.0 / 0.0; // not an error: 2/0 = inf
     let also_not_nan = 0.0 / 2.0; // not an error: 0/2 = 0
 }
diff --git a/src/tools/clippy/tests/versioncheck.rs b/src/tools/clippy/tests/versioncheck.rs
index 76b6126c76c..bc5ed0816cc 100644
--- a/src/tools/clippy/tests/versioncheck.rs
+++ b/src/tools/clippy/tests/versioncheck.rs
@@ -23,6 +23,12 @@ fn check_that_clippy_lints_has_the_same_version_as_clippy() {
 
 #[test]
 fn check_that_clippy_has_the_same_major_version_as_rustc() {
+    // do not run this test inside the upstream rustc repo:
+    // https://github.com/rust-lang/rust-clippy/issues/6683
+    if option_env!("RUSTC_TEST_SUITE").is_some() {
+        return;
+    }
+
     let clippy_version = rustc_tools_util::get_version_info!();
     let clippy_major = clippy_version.major;
     let clippy_minor = clippy_version.minor;