Allow file names to end with '>'

The `rustc_span::FileName` enum already differentiates between real
files and "fake" files such as `<anon>`. We do not need to artificially
forbid real file names from ending in `>`.

compiler/rustc_span/src/lib.rs

@@ -305,7 +305,6 @@ pub enum FileName {
 
 impl From<PathBuf> for FileName {
     fn from(p: PathBuf) -> Self {
-        assert!(!p.to_string_lossy().ends_with('>'));
         FileName::Real(RealFileName::LocalPath(p))
     }
 }

tests/ui/include-macros/silly-file-names.rs

@@ -0,0 +1,7 @@
+// run-pass
+// check-run-results
+
+fn main() {
+    println!(include!("silly-file-names/<leading-lt"));
+    println!(include!("silly-file-names/trailing-gt>"));
+}

tests/ui/include-macros/silly-file-names.run.stdout

@@ -0,0 +1,2 @@
+comes from a file with a name that begins with '<'
+comes from a file with a name that ends with '>'

tests/ui/include-macros/silly-file-names/<leading-lt

@@ -0,0 +1 @@
+"comes from a file with a name that begins with '<'"

tests/ui/include-macros/silly-file-names/trailing-gt>

@@ -0,0 +1 @@
+"comes from a file with a name that ends with '>'"