diff --git a/src/test/ui/dyn-keyword/dyn-2015-edition-keyword-ident-lint.fixed b/src/test/ui/dyn-keyword/dyn-2015-edition-keyword-ident-lint.fixed
new file mode 100644
index 00000000000..153d73c9ea5
--- /dev/null
+++ b/src/test/ui/dyn-keyword/dyn-2015-edition-keyword-ident-lint.fixed
@@ -0,0 +1,81 @@
+// Under the 2015 edition with the keyword_idents lint, `dyn` is not
+// entirely acceptable as an identifier. We currently do not attempt
+// to detect or fix uses of `dyn` under a macro. Since we are testing
+// this file via `rustfix`, we want the rustfix output to be
+// compilable; so the macros here carefully use `dyn` "correctly."
+
+// run-rustfix
+
+#![allow(non_camel_case_types)]
+#![deny(keyword_idents)]
+
+mod outer_mod {
+    pub mod r#dyn {
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+        pub struct r#dyn;
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+    }
+}
+use outer_mod::r#dyn::r#dyn;
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+
+fn main() {
+    match r#dyn { r#dyn => {} }
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+    macro_defn::r#dyn();
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+
+    macro_defn::boxed();
+}
+
+mod macro_defn {
+    use super::Trait;
+
+    macro_rules! r#dyn {
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+
+        // Note that we do not lint nor fix occurrences under macros
+        ($dyn:ident) => { Box<dyn Trait> }
+    }
+
+    pub fn r#dyn() -> ::outer_mod::r#dyn::r#dyn {
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+        ::outer_mod::r#dyn::r#dyn
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+    }
+
+
+
+    pub fn boxed() -> r#dyn!(
+        //~^ ERROR `dyn` is a keyword
+        //~| WARN was previously accepted
+
+            // Note that we do not lint nor fix occurrences under macros
+            dyn
+    )
+    {
+        Box::new(10)
+    }
+}
+
+pub trait Trait { }
+
+impl Trait for u32 { }
diff --git a/src/test/ui/dyn-keyword/dyn-2015-edition-keyword-ident-lint.rs b/src/test/ui/dyn-keyword/dyn-2015-edition-keyword-ident-lint.rs
new file mode 100644
index 00000000000..98ad3a78c13
--- /dev/null
+++ b/src/test/ui/dyn-keyword/dyn-2015-edition-keyword-ident-lint.rs
@@ -0,0 +1,81 @@
+// Under the 2015 edition with the keyword_idents lint, `dyn` is not
+// entirely acceptable as an identifier. We currently do not attempt
+// to detect or fix uses of `dyn` under a macro. Since we are testing
+// this file via `rustfix`, we want the rustfix output to be
+// compilable; so the macros here carefully use `dyn` "correctly."
+
+// run-rustfix
+
+#![allow(non_camel_case_types)]
+#![deny(keyword_idents)]
+
+mod outer_mod {
+    pub mod dyn {
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+        pub struct dyn;
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+    }
+}
+use outer_mod::dyn::dyn;
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+
+fn main() {
+    match dyn { dyn => {} }
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+    macro_defn::dyn();
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+
+    macro_defn::boxed();
+}
+
+mod macro_defn {
+    use super::Trait;
+
+    macro_rules! dyn {
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+
+        // Note that we do not lint nor fix occurrences under macros
+        ($dyn:ident) => { Box<dyn Trait> }
+    }
+
+    pub fn dyn() -> ::outer_mod::dyn::dyn {
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+        ::outer_mod::dyn::dyn
+//~^ ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+//~| ERROR `dyn` is a keyword
+//~| WARN was previously accepted
+    }
+
+
+
+    pub fn boxed() -> dyn!(
+        //~^ ERROR `dyn` is a keyword
+        //~| WARN was previously accepted
+
+            // Note that we do not lint nor fix occurrences under macros
+            dyn
+    )
+    {
+        Box::new(10)
+    }
+}
+
+pub trait Trait { }
+
+impl Trait for u32 { }
diff --git a/src/test/ui/dyn-keyword/dyn-2015-edition-keyword-ident-lint.stderr b/src/test/ui/dyn-keyword/dyn-2015-edition-keyword-ident-lint.stderr
new file mode 100644
index 00000000000..361727733bc
--- /dev/null
+++ b/src/test/ui/dyn-keyword/dyn-2015-edition-keyword-ident-lint.stderr
@@ -0,0 +1,133 @@
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:13:13
+   |
+LL |     pub mod dyn {
+   |             ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+note: lint level defined here
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:10:9
+   |
+LL | #![deny(keyword_idents)]
+   |         ^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:16:20
+   |
+LL |         pub struct dyn;
+   |                    ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:21:16
+   |
+LL | use outer_mod::dyn::dyn;
+   |                ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:21:21
+   |
+LL | use outer_mod::dyn::dyn;
+   |                     ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:28:11
+   |
+LL |     match dyn { dyn => {} }
+   |           ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:28:17
+   |
+LL |     match dyn { dyn => {} }
+   |                 ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:33:17
+   |
+LL |     macro_defn::dyn();
+   |                 ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:43:18
+   |
+LL |     macro_rules! dyn {
+   |                  ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:51:12
+   |
+LL |     pub fn dyn() -> ::outer_mod::dyn::dyn {
+   |            ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:51:34
+   |
+LL |     pub fn dyn() -> ::outer_mod::dyn::dyn {
+   |                                  ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:51:39
+   |
+LL |     pub fn dyn() -> ::outer_mod::dyn::dyn {
+   |                                       ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:58:22
+   |
+LL |         ::outer_mod::dyn::dyn
+   |                      ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:58:27
+   |
+LL |         ::outer_mod::dyn::dyn
+   |                           ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `dyn` is a keyword in the 2018 edition
+  --> $DIR/dyn-2015-edition-keyword-ident-lint.rs:67:23
+   |
+LL |     pub fn boxed() -> dyn!(
+   |                       ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: aborting due to 14 previous errors
+
diff --git a/src/test/ui/dyn-keyword/dyn-2015-idents-in-macros-unlinted.rs b/src/test/ui/dyn-keyword/dyn-2015-idents-in-macros-unlinted.rs
new file mode 100644
index 00000000000..a4ed970bc28
--- /dev/null
+++ b/src/test/ui/dyn-keyword/dyn-2015-idents-in-macros-unlinted.rs
@@ -0,0 +1,24 @@
+// compile-pass
+
+// Under the 2015 edition with the keyword_idents lint, `dyn` is
+// not entirely acceptable as an identifier.
+//
+// We currently do not attempt to detect or fix uses of `dyn` as an
+// identifier under a macro.
+
+#![allow(non_camel_case_types)]
+#![deny(keyword_idents)]
+
+mod outer_mod {
+    pub mod r#dyn {
+        pub struct r#dyn;
+    }
+}
+
+macro_rules! defn_has_dyn_idents {
+    ($arg:ident) => { ::outer_mod::dyn::dyn }
+}
+
+fn main() {
+    defn_has_dyn_idents!(dyn);
+}
diff --git a/src/test/ui/dyn-keyword/dyn-2015-no-warnings-without-lints.rs b/src/test/ui/dyn-keyword/dyn-2015-no-warnings-without-lints.rs
new file mode 100644
index 00000000000..8cef5c2b349
--- /dev/null
+++ b/src/test/ui/dyn-keyword/dyn-2015-no-warnings-without-lints.rs
@@ -0,0 +1,27 @@
+// Under the 2015 edition without the keyword_idents lint, `dyn` is
+// entirely acceptable as an identifier.
+
+// compile-pass
+
+#![allow(non_camel_case_types)]
+
+mod outer_mod {
+    pub mod dyn {
+        pub struct dyn;
+    }
+}
+use outer_mod::dyn::dyn;
+
+fn main() {
+    match dyn { dyn => {} }
+    macro_defn::dyn();
+}
+mod macro_defn {
+    macro_rules! dyn {
+        () => { ::outer_mod::dyn::dyn }
+    }
+
+    pub fn dyn() -> ::outer_mod::dyn::dyn {
+        dyn!()
+    }
+}