[libfuzzer] Use cl driver mode for tests and enable another test on Windows

[metzman]

Summary

When targeting MSVC: compile using clang's cl driver mode (this is needed for
libfuzzer's exit_on_src_pos feature). Don't use -lstdc++ when linking,
it isn't needed and causes a warning.
On Windows: Fix exit_on_src_pos.test by making sure debug info isn't
overwritten during compilation of second binary by using .exe extension.

[metzman]

• Remove /Z7 flag.

[metzman]

• undo accidental change

[metzman]

Matt, please take a look when you get a chance (no rush).

I suspect this is the last exe related problem, but there may be others that have this problem combined with another (like exit_on_src.pos did).

Also, do you know if there is a way to conditionally add a compile flag to a particular compile command in a lit file? If I ever need to add a windows only flag to just one command, I'm not sure what I would need to do (maybe a separate lit file? or I can define an expansion?).

By the way, I can commit this one myself (hooray!)

[metzman]

compiler-rt/test/fuzzer/exit_on_src_pos.test

9 ↗

(On Diff #164304)

I'm not sure why this line has so much whitespace, do you think I should get rid of it.

[morehouse]

compiler-rt/test/fuzzer/exit_on_src_pos.test

9 ↗

(On Diff #164304)

Yes, please fix whitespace.

compiler-rt/test/fuzzer/lit.cfg

72 ↗

(On Diff #164304)

Should we be checking config.target_triple instead?

[metzman]

• remove extra whitespace.
• use target triple

[metzman]

compiler-rt/test/fuzzer/exit_on_src_pos.test

9 ↗

(On Diff #164304)

Done

compiler-rt/test/fuzzer/lit.cfg

72 ↗

(On Diff #164304)

Good idea. Done.

test/fuzzer/exit_on_src_pos.test

-# FIXME: Disabled on Windows until symbolization works properly.
-UNSUPPORTED: windows
 # Temporary use -mllvm -use-unknown-locations=Disable so that
 # all instructions have debug info (file line numbers) attached.
 # TODO: Find out why test fails on Darwin with -O2.
-RUN: %cpp_compiler -O0 %S/SimpleTest.cpp -o %t-SimpleTest -mllvm -use-unknown-locations=Disable
-RUN: %cpp_compiler -O0 %S/ShrinkControlFlowTest.cpp -o %t-ShrinkControlFlowTest
+# Binaries must end in .exe or else symbolization will break on Windows because of how periods
+# in expansion of %t cause the compiler to overwrite .lib and .exp files.
+RUN: %cpp_compiler -O0 %S/SimpleTest.cpp -o %t-SimpleTest.exe -mllvm -use-unknown-locations=Disable
+RUN: %cpp_compiler -O0 %S/ShrinkControlFlowTest.cpp -o %t-ShrinkControlFlowTest.exe
 
-RUN: %run %t-SimpleTest  -exit_on_src_pos=SimpleTest.cpp:18                 2>&1 | FileCheck %s --check-prefix=EXIT_ON_SRC_POS
-RUN: %run %t-ShrinkControlFlowTest  -exit_on_src_pos=Foo 2>&1 | FileCheck %s --check-prefix=EXIT_ON_SRC_POS
+RUN: %run %t-SimpleTest.exe  -exit_on_src_pos=SimpleTest.cpp:18 2>&1 | FileCheck %s --check-prefix=EXIT_ON_SRC_POS
+RUN: %run %t-ShrinkControlFlowTest.exe  -exit_on_src_pos=Foo 2>&1 | FileCheck %s --check-prefix=EXIT_ON_SRC_POS
 EXIT_ON_SRC_POS: INFO: found line matching '{{.*}}', exiting.

test/fuzzer/lit.cfg

def generate_compiler_cmd(is_cpp=True, fuzzer_enabled=True, msan_enabled=False):
   extra_cmd = config.target_flags
   if config.clang and config.stdlib == 'libc++':
     link_cmd = '-stdlib=libc++ -Wl,-rpath=%s' % config.runtime_library_dir
   elif config.clang and config.stdlib == 'static-libc++':
     link_cmd = '-stdlib=libc++ -lc++abi -static-libstdc++ -Wl,-rpath=%s' % (
         config.runtime_library_dir)
   elif any(x in config.target_triple for x in ('darwin', 'freebsd')):
     link_cmd = '-lc++'
+  elif 'windows-msvc' in config.target_triple:
+    link_cmd = ''
   else:
     link_cmd = '-lstdc++'
 
-  if is_cpp and not sys.platform.startswith('win'):
+  if is_cpp and 'windows-msvc' in config.target_triple:
+    std_cmd = '--driver-mode=cl'
+  elif is_cpp:
     std_cmd = '--driver-mode=g++ -std=c++11'
   else:
     std_cmd = ''
 
   if msan_enabled:
     sanitizers = ['memory']
   else:
     sanitizers = ['address']