Don't trim non-alphanumeric characters in 'file not found' errors for include directives.

[jgorbe]

Summary

r342177 introduced a hint in cases where an #included file is not found. It tries to find a suggestion by removing leading or trailing non-alphanumeric characters and checking if a matching file exists, then it reports an error like:

include-likely-typo.c:3:10: error: '<empty_file_to_include.h>' file not found, did you mean 'empty_file_to_include.h'?
#include "<empty_file_to_include.h>" // expected-error {{'<empty_file_to_include.h>' file not found, did you mean 'empty_file_to_include.h'?}}
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
         "empty_file_to_include.h"
1 error generated.

However, if a hint is not found, the error message will show only the trimmed name we use to look for a hint, so:

#include "/non_existing_file."

will result in:

include-leading-nonalpha-no-suggest.c:3:10: fatal error: 'non_existing_file_to_include.h' file not found
#include "/non_existing_file_to_include.h" // expected-error {{'/non_existing_file_to_include.h' file not found}}
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

where the name reported after "fatal error:" doesn't match what the user wrote.

This change reports the original file name instead of the trimmed one when a suggestion is not found.

[christylee]

Thanks for the fix!

[aaron.ballman]

LGTM!

lib/Lex/PPDirectives.cpp

if (!SuppressIncludeNotFoundError) {
           Diag(FilenameTok, diag::err_pp_file_not_found_angled_include_not_fatal) <<
             Filename <<
             FixItHint::CreateReplacement(Range, "\"" + Filename.str() + "\"");
         }
       }
 
       // Check for likely typos due to leading or trailing non-isAlphanumeric
       // characters
-      if (!File) {
-        StringRef OriginalFilename = Filename;
+      if (!File) {
         while (!isAlphanumeric(Filename.front())) {
           Filename = Filename.drop_front();
         }
         while (!isAlphanumeric(Filename.back())) {
           Filename = Filename.drop_back();
         }
 
         File = LookupFile(
if (!SuppressIncludeNotFoundError) {
                                      Range, "\"" + Filename.str() + "\"");
           Diag(FilenameTok, diag::err_pp_file_not_found_typo_not_fatal)
               << OriginalFilename << Filename << Hint;
         }
       }
 
       // If the file is still not found, just go with the vanilla diagnostic
       if (!File)
-        Diag(FilenameTok, diag::err_pp_file_not_found) << Filename
+        Diag(FilenameTok, diag::err_pp_file_not_found) << OriginalFilename
                                                        << FilenameRange;
     }
   }
 
   if (usingPCHWithThroughHeader() && SkippingUntilPCHThroughHeader) {
     if (isPCHThroughHeader(File))
       SkippingUntilPCHThroughHeader = false;
     return;