[Static analysis] Encodes a filename before inserting it into a URL. (#120810)

This fixes a bug where report links generated from files such as
StylePrimitiveNumericTypes+Conversions.h in WebKit result in an error.

---------

Co-authored-by: Brianna Fan <[email protected]>

Author: rniwa

clang/tools/scan-build/bin/scan-build

@@ -820,7 +820,8 @@ ENDTEXT
       }
 
       # Emit the "View" link.
-      print OUT "<td><a href=\"$ReportFile#EndPath\">View Report</a></td>";
+      my $EncodedReport = URLEscape($ReportFile);
+      print OUT "<td><a href=\"$EncodedReport#EndPath\">View Report</a></td>";
 
       # Emit REPORTBUG markers.
       print OUT "\n<!-- REPORTBUG id=\"$ReportFile\" -->\n";
@@ -1465,6 +1466,16 @@ sub HtmlEscape {
   return $tmp;
 }
 
+##----------------------------------------------------------------------------##
+# URLEscape - encode characters that are special in URLs
+##----------------------------------------------------------------------------##
+
+sub URLEscape {
+  my $arg = shift || '';
+  $arg =~ s/\+/%2B/g;
+  return $arg;
+}
+
 ##----------------------------------------------------------------------------##
 # ShellEscape - backslash escape characters that are special to the shell
 ##----------------------------------------------------------------------------##