diff --git a/Cargo.toml b/Cargo.toml
index c37104850..c41f0f585 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -47,7 +47,7 @@ rustc_tools_util = { version = "0.1.1", path = "rustc_tools_util"}
 [dev-dependencies]
 clippy_dev = { version = "0.0.1", path = "clippy_dev" }
 cargo_metadata = "0.7.1"
-compiletest_rs = "0.3.18"
+compiletest_rs = "=0.3.18"
 lazy_static = "1.0"
 serde_derive = "1.0"
 clippy-mini-macro-test = { version = "0.2", path = "mini-macro" }
diff --git a/clippy_lints/src/eta_reduction.rs b/clippy_lints/src/eta_reduction.rs
index 87a82b2a1..59e6ec768 100644
--- a/clippy_lints/src/eta_reduction.rs
+++ b/clippy_lints/src/eta_reduction.rs
@@ -129,18 +129,13 @@ fn get_ufcs_type_name(
     let actual_type_of_self = &cx.tables.node_type(self_arg.hir_id).sty;
 
     if let Some(trait_id) = cx.tcx.trait_of_item(method_def_id) {
-        //if the method expectes &self, ufcs requires explicit borrowing so closure can't be removed
-        return match (expected_type_of_self, actual_type_of_self) {
-            (ty::Ref(_, _, _), ty::Ref(_, _, _)) => Some(cx.tcx.item_path_str(trait_id)),
-            (l, r) => match (l, r) {
-                (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _)) => None,
-                (_, _) => Some(cx.tcx.item_path_str(trait_id)),
-            },
-        };
+        if match_borrow_depth(expected_type_of_self, actual_type_of_self) {
+            return Some(cx.tcx.item_path_str(trait_id));
+        }
     }
 
     cx.tcx.impl_of_method(method_def_id).and_then(|_| {
-        //a type may implicitly implement other types methods (e.g. Deref)
+        //a type may implicitly implement other type's methods (e.g. Deref)
         if match_types(expected_type_of_self, actual_type_of_self) {
             return Some(get_type_name(cx, &actual_type_of_self));
         }
@@ -148,6 +143,16 @@ fn get_ufcs_type_name(
     })
 }
 
+fn match_borrow_depth(lhs: &ty::TyKind<'_>, rhs: &ty::TyKind<'_>) -> bool {
+    match (lhs, rhs) {
+        (ty::Ref(_, t1, _), ty::Ref(_, t2, _)) => match_borrow_depth(&t1.sty, &t2.sty),
+        (l, r) => match (l, r) {
+            (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _)) => false,
+            (_, _) => true,
+        },
+    }
+}
+
 fn match_types(lhs: &ty::TyKind<'_>, rhs: &ty::TyKind<'_>) -> bool {
     match (lhs, rhs) {
         (ty::Bool, ty::Bool)
diff --git a/clippy_lints/src/functions.rs b/clippy_lints/src/functions.rs
index 7ea01ad5e..b58587087 100644
--- a/clippy_lints/src/functions.rs
+++ b/clippy_lints/src/functions.rs
@@ -150,7 +150,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
 
         let nodeid = cx.tcx.hir().hir_to_node_id(hir_id);
         self.check_raw_ptr(cx, unsafety, decl, body, nodeid);
-        self.check_line_number(cx, span);
+        self.check_line_number(cx, span, body);
     }
 
     fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
@@ -181,12 +181,12 @@ impl<'a, 'tcx> Functions {
         }
     }
 
-    fn check_line_number(self, cx: &LateContext<'_, '_>, span: Span) {
+    fn check_line_number(self, cx: &LateContext<'_, '_>, span: Span, body: &'tcx hir::Body) {
         if in_external_macro(cx.sess(), span) {
             return;
         }
 
-        let code_snippet = snippet(cx, span, "..");
+        let code_snippet = snippet(cx, body.value.span, "..");
         let mut line_count: u64 = 0;
         let mut in_comment = false;
         let mut code_in_line;
diff --git a/clippy_lints/src/missing_const_for_fn.rs b/clippy_lints/src/missing_const_for_fn.rs
index 00a3de063..633105ff6 100644
--- a/clippy_lints/src/missing_const_for_fn.rs
+++ b/clippy_lints/src/missing_const_for_fn.rs
@@ -1,8 +1,9 @@
 use crate::utils::{is_entrypoint_fn, span_lint};
+use if_chain::if_chain;
 use rustc::hir;
 use rustc::hir::intravisit::FnKind;
 use rustc::hir::{Body, Constness, FnDecl, HirId};
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintPass};
 use rustc::{declare_tool_lint, lint_array};
 use rustc_mir::transform::qualify_min_const_fn::is_min_const_fn;
 use syntax_pos::Span;
@@ -82,7 +83,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingConstForFn {
     ) {
         let def_id = cx.tcx.hir().local_def_id_from_hir_id(hir_id);
 
-        if is_entrypoint_fn(cx, def_id) {
+        if in_external_macro(cx.tcx.sess, span) || is_entrypoint_fn(cx, def_id) {
             return;
         }
 
@@ -95,7 +96,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingConstForFn {
                 }
             },
             FnKind::Method(_, sig, ..) => {
-                if already_const(sig.header) {
+                if is_trait_method(cx, hir_id) || already_const(sig.header) {
                     return;
                 }
             },
@@ -114,6 +115,18 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingConstForFn {
     }
 }
 
+fn is_trait_method(cx: &LateContext<'_, '_>, hir_id: HirId) -> bool {
+    // Get the implemented trait for the current function
+    let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
+    if_chain! {
+        if parent_impl != hir::CRATE_HIR_ID;
+        if let hir::Node::Item(item) = cx.tcx.hir().get_by_hir_id(parent_impl);
+        if let hir::ItemKind::Impl(_, _, _, _, Some(_trait_ref), _, _) = &item.node;
+        then { return true; }
+    }
+    false
+}
+
 // We don't have to lint on something that's already `const`
 fn already_const(header: hir::FnHeader) -> bool {
     header.constness == Constness::Const
diff --git a/tests/ui/crashes/ice-3747.rs b/tests/ui/crashes/ice-3747.rs
new file mode 100644
index 000000000..cdf018cbc
--- /dev/null
+++ b/tests/ui/crashes/ice-3747.rs
@@ -0,0 +1,17 @@
+/// Test for https://github.com/rust-lang/rust-clippy/issues/3747
+
+macro_rules! a {
+    ( $pub:tt $($attr:tt)* ) => {
+        $($attr)* $pub fn say_hello() {}
+    };
+}
+
+macro_rules! b {
+    () => {
+        a! { pub }
+    };
+}
+
+b! {}
+
+fn main() {}
diff --git a/tests/ui/eta.rs b/tests/ui/eta.rs
index 6eeb093ea..f777939c6 100644
--- a/tests/ui/eta.rs
+++ b/tests/ui/eta.rs
@@ -88,6 +88,14 @@ fn test_redundant_closures_containing_method_calls() {
     let c = Some(TestStruct { some_ref: &i })
         .as_ref()
         .map(|c| c.to_ascii_uppercase());
+
+    fn test_different_borrow_levels<T>(t: &[&T])
+    where
+        T: TestTrait,
+    {
+        t.iter().filter(|x| x.trait_foo_ref());
+        t.iter().map(|x| x.trait_foo_ref());
+    }
 }
 
 fn meta<F>(f: F)
diff --git a/tests/ui/missing_const_for_fn/cant_be_const.rs b/tests/ui/missing_const_for_fn/cant_be_const.rs
index 36efe16b8..115cc954d 100644
--- a/tests/ui/missing_const_for_fn/cant_be_const.rs
+++ b/tests/ui/missing_const_for_fn/cant_be_const.rs
@@ -55,3 +55,16 @@ trait Foo {
         33
     }
 }
+
+// Don't lint in external macros (derive)
+#[derive(PartialEq, Eq)]
+struct Point(isize, isize);
+
+impl std::ops::Add for Point {
+    type Output = Self;
+
+    // Don't lint in trait impls of derived methods
+    fn add(self, other: Self) -> Self {
+        Point(self.0 + other.0, self.1 + other.1)
+    }
+}