[demangler] improve test harness

[urnathan]

Summary

The demangler test harness is a little unclear. The failed demangling message always causes me to think about 'reality', changing to a simple 'Found' seems clearer.

The expected-to-fail tests abort as soon as one passes, rather than continue, and then abort if any passed. This changes that loop to fail at the end, in a similar manner to the expected-to-work loop.

I've not addressed the obvious clang-format fails of the entire file :)

[ChuanqiXu]

I don't familiar with CXXABI. But I thought this one should be NFC and good.

libcxxabi/test/test_demangle.pass.cpp

 void test()
 {
     std::size_t len = 0;
     char* buf = nullptr;
     bool failed = false;
     for (unsigned i = 0; i < N; ++i)
     {
         int status;
-        char* demang = __cxxabiv1::__cxa_demangle(cases[i][0], buf, &len, &status);
-        if (demang == 0 || std::strcmp(demang, cases[i][1]) != 0)
+        char* demang =
+            __cxxabiv1::__cxa_demangle(cases[i][0], buf, &len, &status);
+        if (!demang || std::strcmp(demang, cases[i][1]) != 0)
         {
-            std::printf("ERROR demangling %s\nexpected: %s\n", cases[i][0], cases[i][1]);
-            if (demang)
-            {
-                std::printf(" reality: %s\n", demang);
-                buf = demang;
-                failed = true;
-            }
-            else
-            {
-                std::printf("Got instead: NULL, %d\n", status);
-                failed = true;
-            }
-        }
-        else
-        {
-            buf = demang;
-        }
-    }
-    assert(!failed);
+            std::printf("ERROR demangling %s\nexpected: %s\n",
+                        cases[i][0], cases[i][1]);
+            std::printf("Got: %d, %s\n", status, demang ? demang : "(null)");
+        if (demang)
     free(buf);
+    assert(!failed && "demangle failed");
 }
 
 void test_invalid_cases()
 {
     std::size_t len = 0;
     char* buf = nullptr;
+    bool passed = false;
     for (unsigned i = 0; i < NI; ++i)
     {
         int status;
-        char* demang = __cxxabiv1::__cxa_demangle(invalid_cases[i], buf, &len, &status);
+        char* demang =
+            __cxxabiv1::__cxa_demangle(invalid_cases[i], buf, &len, &status);
         if (status != -2)
         {
             std::printf("%s should be invalid but is not\n", invalid_cases[i]);
-            std::printf("Got status %d\n", status);
-            assert(status == -2);
+            std::printf("Got: %d, %s\n", status, demang ? demang : "(null)");
+            passed = true;
         }
-        else
-        {
-            buf = demang;
-        }
-    }
+        if (demang)
     free(buf);
+    assert(!passed && "demangle did not fail");
 }
 
 const char *xfail_cases[] = {
     "_ZW6FooBarE2f3v", // C++ modules TS
 
     // FIXME: Why does clang generate the "cp" expr?
     "_ZN5test11bIsEEDTcp3foocvT__EEES1_",
 };