[clang-tidy] Properly forward clang-tidy output when running tests

[nicovank]

Summary

When running tests, the check_clang_tidy script encodes the output string, making it hard to read when debugging checks. This removes the .encode() call.

Test Plan:
Making a new default check for testing (as of right now, it includes a failing test):

[~/llvm-project/clang-tools-extra] python3 clang-tidy/add_new_check.py bugprone example
<...>

Pre-changes:

[~/llvm-project/build] ninja check-clang-tools
<...>
------------------------ clang-tidy output -----------------------
b"1 warning generated.\n/data/users/nvankempen/llvm-project/build/Debug/tools/clang/tools/extra/test/clang-tidy/checkers/Output/bugprone-example.cpp.tmp.cpp:4:6: warning: function 'f' is insufficiently awesome [bugprone-example]\nvoid f();\n     ^\n/data/users/nvankempen/llvm-project/build/Debug/tools/clang/tools/extra/test/clang-tidy/checkers/Output/bugprone-example.cpp.tmp.cpp:4:6: note: insert 'awesome'\nvoid f();\n     ^\n     awesome_\n"

------------------------------------------------------------------
<...>

Post-changes:

[~/llvm-project/build] ninja check-clang-tools
<...>
------------------------ clang-tidy output -----------------------
1 warning generated.
/data/users/nvankempen/llvm-project/build/Debug/tools/clang/tools/extra/test/clang-tidy/checkers/Output/bugprone-example.cpp.tmp.cpp:4:6: warning: function 'f' is insufficiently awesome [bugprone-example]
void f();
     ^
/data/users/nvankempen/llvm-project/build/Debug/tools/clang/tools/extra/test/clang-tidy/checkers/Output/bugprone-example.cpp.tmp.cpp:4:6: note: insert 'awesome'
void f();
     ^
     awesome_

------------------------------------------------------------------
<...>

[nicovank]

Rebase.

[nicovank]

Looks like this causes the misc-misleading-identifier test to fail on the BuildKite Windows setup because it uses cp1252 and not utf-8. I think this is why the encode was added in the first place. This workaround should hopefully fix this, it will display unicode characters as '?' when stdout does not support utf-8.

[njames93]

Thank you for this, it has been annoying me for a while.
I'll give a tentative LG, but I'm no expert in this area so see what everyone else says first.

[nicovank]

Ping, adding one more person who has history changing this script.

[aaron.ballman]

FWIW, I'm also a tentative LG on these changes. I'm not certain if there's a reason why we did things this way in the first place, but I think the new output is more readable.

[nicovank]

Did some digging, looks like this was added in rG7f92a1a84b96, most likely to also fix that CI build error with misc-misleading-identifier.

[LegalizeAdulthood]

Thanks for this, like Nathan James this has been pestering me for a while :)

[njames93]

I'd say land this, but keep a close eye on the build bots as it may need reverting.

[nicovank]

I do not have commit access for the LLVM repository, could one of you commit this for me (Nicolas van Kempen <[e-mail]>)?

I can keep an eye on this today, otherwise I will discuss with someone internally and commit Tuesday.

[LegalizeAdulthood]

I will submit it

clang-tools-extra/test/clang-tidy/check_clang_tidy.py

class CheckRunner:
   def run_clang_tidy(self):
     args = ['clang-tidy', self.temp_file_name, '-fix', '--checks=-*,' + self.check_name] + \
         self.clang_tidy_extra_args + ['--'] + self.clang_extra_args
     if self.expect_clang_tidy_error:
       args.insert(0, 'not')
     print('Running ' + repr(args) + '...')
     clang_tidy_output = try_run(args)
     print('------------------------ clang-tidy output -----------------------')
-    print(clang_tidy_output.encode())
-    print('\n------------------------------------------------------------------')
+    print(clang_tidy_output.encode(sys.stdout.encoding, errors="replace").decode(sys.stdout.encoding))
+    print('------------------------------------------------------------------')
 
     diff_output = try_run(['diff', '-u', self.original_file_name, self.temp_file_name], False)
-    print('------------------------------ Fixes -----------------------------\n' +
-          diff_output +
-          '\n------------------------------------------------------------------')
+    print('------------------------------ Fixes -----------------------------')
+    print(diff_output)
+    print('------------------------------------------------------------------')
     return clang_tidy_output
 
   def check_fixes(self):
     if self.has_check_fixes:
       try_run(['FileCheck', '-input-file=' + self.temp_file_name, self.input_file_name,
               '-check-prefixes=' + ','.join(self.fixes.prefixes),
               '-strict-whitespace'])