Add UI test for #100199

src/test/ui/macros/auxiliary/issue-100199.rs

@@ -0,0 +1,18 @@
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+#![feature(proc_macro_quote)]
+
+extern crate proc_macro;
+
+use proc_macro::{quote, Ident, Span, TokenStream, TokenTree};
+
+#[proc_macro_attribute]
+pub fn struct_with_bound(_: TokenStream, _: TokenStream) -> TokenStream {
+    let crate_ident = TokenTree::Ident(Ident::new("crate", Span::call_site()));
+    let trait_ident = TokenTree::Ident(Ident::new("MyTrait", Span::call_site()));
+    quote!(
+        struct Foo<T: $crate_ident::$trait_ident> {}
+    )
+}

src/test/ui/macros/issue-100199.rs

@@ -0,0 +1,16 @@
+#[issue_100199::struct_with_bound] //~ ERROR cannot find trait `MyTrait` in the crate root
+struct Foo {}
+// The above must be on the first line so that it's span points to pos 0.
+// This used to trigger an ICE because the diagnostic emitter would get
+// an unexpected dummy span (lo == 0 == hi) while attempting to print a
+// suggestion.
+
+// aux-build: issue-100199.rs
+
+extern crate issue_100199;
+
+mod traits {
+    pub trait MyTrait {}
+}
+
+fn main() {}

src/test/ui/macros/issue-100199.stderr

@@ -0,0 +1,15 @@
+error[E0405]: cannot find trait `MyTrait` in the crate root
+  --> $DIR/issue-100199.rs:1:1
+   |
+LL | #[issue_100199::struct_with_bound]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not found in the crate root
+   |
+   = note: this error originates in the attribute macro `issue_100199::struct_with_bound` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing this trait
+   |
+LL | use traits::MyTrait;
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0405`.