From 152811d8bf389fce7328ba7bc50c26c34afb0d81 Mon Sep 17 00:00:00 2001
From: David <daboross@daboross.net>
Date: Sun, 2 Feb 2020 11:28:32 -0800
Subject: [PATCH] Change expansion error to be non-fatal

Changes the error handler for inner attributes that replace the root
with a non-module. Previously it would emit a fatal error. It now emits
an empty expasion and a non-fatal error like the existing handler for a
failed expansion.
---
 src/librustc_expand/expand.rs                       |  4 +++-
 .../proc-macro/issue-59191-replace-root-with-fn.rs  |  1 +
 .../issue-59191-replace-root-with-fn.stderr         | 13 +++++++++++--
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/librustc_expand/expand.rs b/src/librustc_expand/expand.rs
index 1aa4f11a130..4e0fec9ce1d 100644
--- a/src/librustc_expand/expand.rs
+++ b/src/librustc_expand/expand.rs
@@ -364,7 +364,9 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 krate.module = ast::Mod { inner: orig_mod_span, items: vec![], inline: true };
             }
             Some(ast::Item { span, kind, .. }) => {
-                self.cx.span_fatal(
+                krate.attrs = vec![];
+                krate.module = ast::Mod { inner: orig_mod_span, items: vec![], inline: true };
+                self.cx.span_err(
                     span,
                     &format!(
                         "expected crate top-level item to be a module after macro expansion, found a {}",
diff --git a/src/test/ui/proc-macro/issue-59191-replace-root-with-fn.rs b/src/test/ui/proc-macro/issue-59191-replace-root-with-fn.rs
index 039878af56e..a59cacb8bde 100644
--- a/src/test/ui/proc-macro/issue-59191-replace-root-with-fn.rs
+++ b/src/test/ui/proc-macro/issue-59191-replace-root-with-fn.rs
@@ -3,5 +3,6 @@
 // Test that using a macro to replace the entire crate tree with a non-'mod' item errors out nicely.
 // `issue_59191::no_main` replaces whatever's passed in with `fn main() {}`.
 #![feature(custom_inner_attributes)]
+//~^ ERROR `main` function not found in crate `issue_59191_replace_root_with_fn` [E0601]
 #![issue_59191::no_main]
 //~^ ERROR expected crate top-level item to be a module after macro expansion, found a function
diff --git a/src/test/ui/proc-macro/issue-59191-replace-root-with-fn.stderr b/src/test/ui/proc-macro/issue-59191-replace-root-with-fn.stderr
index 1bda86551d4..e0a3caef9db 100644
--- a/src/test/ui/proc-macro/issue-59191-replace-root-with-fn.stderr
+++ b/src/test/ui/proc-macro/issue-59191-replace-root-with-fn.stderr
@@ -1,8 +1,17 @@
 error: expected crate top-level item to be a module after macro expansion, found a function
-  --> $DIR/issue-59191-replace-root-with-fn.rs:6:1
+  --> $DIR/issue-59191-replace-root-with-fn.rs:7:1
    |
 LL | #![issue_59191::no_main]
    | ^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to previous error
+error[E0601]: `main` function not found in crate `issue_59191_replace_root_with_fn`
+  --> $DIR/issue-59191-replace-root-with-fn.rs:5:1
+   |
+LL | / #![feature(custom_inner_attributes)]
+LL | |
+LL | | #![issue_59191::no_main]
+   | |________________________^ consider adding a `main` function to `$DIR/issue-59191-replace-root-with-fn.rs`
 
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0601`.