From 11f3476c59ee013c017e669676cfaca00a67b3f1 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Tue, 6 Oct 2020 14:29:42 +0200
Subject: [PATCH] Enforce whitespace ascii character check for doc alias

---
 compiler/rustc_passes/src/check_attr.rs         | 10 ++++++++++
 src/test/rustdoc-ui/check-doc-alias-attr.rs     |  2 ++
 src/test/rustdoc-ui/check-doc-alias-attr.stderr | 14 +++++++++++++-
 src/test/ui/check-doc-alias-attr.rs             |  2 ++
 src/test/ui/check-doc-alias-attr.stderr         | 14 +++++++++++++-
 5 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index e8e54c3cfaa..1acaa4c6eff 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -303,6 +303,16 @@ impl CheckAttrVisitor<'tcx> {
                                 .emit();
                             return false;
                         }
+                        if doc_alias.starts_with(' ') || doc_alias.ends_with(' ') {
+                            self.tcx
+                                .sess
+                                .struct_span_err(
+                                    meta.span(),
+                                    "`#[doc(alias = \"...\")]` cannot start or end with ' '",
+                                )
+                                .emit();
+                            return false;
+                        }
                         if let Some(err) = match target {
                             Target::Impl => Some("implementation block"),
                             Target::ForeignMod => Some("extern block"),
diff --git a/src/test/rustdoc-ui/check-doc-alias-attr.rs b/src/test/rustdoc-ui/check-doc-alias-attr.rs
index d55be9f120c..0ca2349a43b 100644
--- a/src/test/rustdoc-ui/check-doc-alias-attr.rs
+++ b/src/test/rustdoc-ui/check-doc-alias-attr.rs
@@ -12,4 +12,6 @@ pub struct Bar;
 #[doc(alias = "
 ")] //~^ ERROR
 #[doc(alias = "\t")] //~ ERROR
+#[doc(alias = " hello")] //~ ERROR
+#[doc(alias = "hello ")] //~ ERROR
 pub struct Foo;
diff --git a/src/test/rustdoc-ui/check-doc-alias-attr.stderr b/src/test/rustdoc-ui/check-doc-alias-attr.stderr
index 97444c69ff1..2c417a3bb65 100644
--- a/src/test/rustdoc-ui/check-doc-alias-attr.stderr
+++ b/src/test/rustdoc-ui/check-doc-alias-attr.stderr
@@ -42,5 +42,17 @@ error: '\t' character isn't allowed in `#[doc(alias = "...")]`
 LL | #[doc(alias = "\t")]
    |       ^^^^^^^^^^^^
 
-error: aborting due to 7 previous errors
+error: `#[doc(alias = "...")]` cannot start or end with ' '
+  --> $DIR/check-doc-alias-attr.rs:15:7
+   |
+LL | #[doc(alias = " hello")]
+   |       ^^^^^^^^^^^^^^^^
+
+error: `#[doc(alias = "...")]` cannot start or end with ' '
+  --> $DIR/check-doc-alias-attr.rs:16:7
+   |
+LL | #[doc(alias = "hello ")]
+   |       ^^^^^^^^^^^^^^^^
+
+error: aborting due to 9 previous errors
 
diff --git a/src/test/ui/check-doc-alias-attr.rs b/src/test/ui/check-doc-alias-attr.rs
index d55be9f120c..0ca2349a43b 100644
--- a/src/test/ui/check-doc-alias-attr.rs
+++ b/src/test/ui/check-doc-alias-attr.rs
@@ -12,4 +12,6 @@ pub struct Bar;
 #[doc(alias = "
 ")] //~^ ERROR
 #[doc(alias = "\t")] //~ ERROR
+#[doc(alias = " hello")] //~ ERROR
+#[doc(alias = "hello ")] //~ ERROR
 pub struct Foo;
diff --git a/src/test/ui/check-doc-alias-attr.stderr b/src/test/ui/check-doc-alias-attr.stderr
index 97444c69ff1..2c417a3bb65 100644
--- a/src/test/ui/check-doc-alias-attr.stderr
+++ b/src/test/ui/check-doc-alias-attr.stderr
@@ -42,5 +42,17 @@ error: '\t' character isn't allowed in `#[doc(alias = "...")]`
 LL | #[doc(alias = "\t")]
    |       ^^^^^^^^^^^^
 
-error: aborting due to 7 previous errors
+error: `#[doc(alias = "...")]` cannot start or end with ' '
+  --> $DIR/check-doc-alias-attr.rs:15:7
+   |
+LL | #[doc(alias = " hello")]
+   |       ^^^^^^^^^^^^^^^^
+
+error: `#[doc(alias = "...")]` cannot start or end with ' '
+  --> $DIR/check-doc-alias-attr.rs:16:7
+   |
+LL | #[doc(alias = "hello ")]
+   |       ^^^^^^^^^^^^^^^^
+
+error: aborting due to 9 previous errors