diff --git a/src/librustc/lint/builtin.rs b/src/librustc/lint/builtin.rs
index 495b4d32e065..4184cba7db3e 100644
--- a/src/librustc/lint/builtin.rs
+++ b/src/librustc/lint/builtin.rs
@@ -335,7 +335,7 @@ declare_lint! {
 pub mod parser {
     declare_lint! {
         pub QUESTION_MARK_MACRO_SEP,
-        Warn,
+        Allow,
         "detects the use of `?` as a macro separator"
     }
 }
diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index 9748e2947eeb..4b077aa8dd4c 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -1807,6 +1807,7 @@ mod tests {
             raw_identifier_spans: Lock::new(Vec::new()),
             registered_diagnostics: Lock::new(ErrorMap::new()),
             non_modrs_mods: Lock::new(vec![]),
+            buffered_lints: Lock::new(vec![]),
         }
     }
 
diff --git a/src/test/run-pass-fulldeps/auxiliary/procedural_mbe_matching.rs b/src/test/run-pass-fulldeps/auxiliary/procedural_mbe_matching.rs
index 664e9eeb3e04..f1777745e06c 100644
--- a/src/test/run-pass-fulldeps/auxiliary/procedural_mbe_matching.rs
+++ b/src/test/run-pass-fulldeps/auxiliary/procedural_mbe_matching.rs
@@ -20,7 +20,7 @@ extern crate rustc_plugin;
 
 use syntax::feature_gate::Features;
 use syntax::parse::token::{NtExpr, NtPat};
-use syntax::ast::{Ident, Pat};
+use syntax::ast::{Ident, Pat, NodeId};
 use syntax::tokenstream::{TokenTree};
 use syntax::ext::base::{ExtCtxt, MacResult, MacEager};
 use syntax::ext::build::AstBuilder;
@@ -41,7 +41,9 @@ fn expand_mbe_matches(cx: &mut ExtCtxt, _: Span, args: &[TokenTree])
                                     cx.parse_sess,
                                     &Features::new(),
                                     &[],
-                                    Edition::Edition2015);
+                                    Edition::Edition2015,
+                                    // not used...
+                                    NodeId::new(0));
     let map = match TokenTree::parse(cx, &mbe_matcher, args.iter().cloned().collect()) {
         Success(map) => map,
         Failure(_, tok) => {
diff --git a/src/test/ui/issue-39388.stderr b/src/test/ui/issue-39388.stderr
index a38d38a51ade..dc19487f3af6 100644
--- a/src/test/ui/issue-39388.stderr
+++ b/src/test/ui/issue-39388.stderr
@@ -1,7 +1,7 @@
-error: expected one of: `*`, `+`, or `?`
+error: expected `*` or `+`
   --> $DIR/issue-39388.rs:14:22
    |
-LL |     (($($a:tt)*) = ($($b:tt))*) => { //~ ERROR expected one of: `*`, `+`, or `?`
+LL |     (($($a:tt)*) = ($($b:tt))*) => { //~ ERROR expected `*` or `+`
    |                      ^^^^^^^
 
 error: aborting due to previous error
diff --git a/src/test/ui/macros/macro-at-most-once-rep-2015-ques-sep.rs b/src/test/ui/macros/macro-at-most-once-rep-2015-ques-sep.rs
index 4b3dfbdc2e8a..2e06b4bd5c24 100644
--- a/src/test/ui/macros/macro-at-most-once-rep-2015-ques-sep.rs
+++ b/src/test/ui/macros/macro-at-most-once-rep-2015-ques-sep.rs
@@ -14,12 +14,16 @@
 // compile-flags: --edition=2015
 // compile-pass
 
+#![warn(rust_2018_compatibility)]
+
 macro_rules! bar {
     ($(a)?*) => {} //~WARN using `?` as a separator
+    //~^WARN this was previously accepted
 }
 
 macro_rules! baz {
     ($(a)?+) => {} //~WARN using `?` as a separator
+    //~^WARN this was previously accepted
 }
 
 fn main() {
diff --git a/src/test/ui/macros/macro-at-most-once-rep-2015-ques-sep.stderr b/src/test/ui/macros/macro-at-most-once-rep-2015-ques-sep.stderr
index 0ab4138864e0..db1872c24134 100644
--- a/src/test/ui/macros/macro-at-most-once-rep-2015-ques-sep.stderr
+++ b/src/test/ui/macros/macro-at-most-once-rep-2015-ques-sep.stderr
@@ -1,12 +1,24 @@
 warning: using `?` as a separator is deprecated and will be a hard error in an upcoming edition
-  --> $DIR/macro-at-most-once-rep-2015-ques-sep.rs:18:10
+  --> $DIR/macro-at-most-once-rep-2015-ques-sep.rs:20:10
    |
 LL |     ($(a)?*) => {} //~WARN using `?` as a separator
    |          ^
+   |
+note: lint level defined here
+  --> $DIR/macro-at-most-once-rep-2015-ques-sep.rs:17:9
+   |
+LL | #![warn(rust_2018_compatibility)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^
+   = note: #[warn(question_mark_macro_sep)] implied by #[warn(rust_2018_compatibility)]
+   = 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 #48075 <https://github.com/rust-lang/rust/issues/48075>
 
 warning: using `?` as a separator is deprecated and will be a hard error in an upcoming edition
-  --> $DIR/macro-at-most-once-rep-2015-ques-sep.rs:22:10
+  --> $DIR/macro-at-most-once-rep-2015-ques-sep.rs:25:10
    |
 LL |     ($(a)?+) => {} //~WARN using `?` as a separator
    |          ^
+   |
+   = 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 #48075 <https://github.com/rust-lang/rust/issues/48075>