[libc++] Fix tests on musl (#85085) (#86934)

One or two of the tests need slight tweaks to make them pass when
building with musl.

This patch is a re-application of b61fb18 which was reverted in 0847c90
because it broke the build.

rdar://118885724

Co-authored-by: Alastair Houghton <ahoughton@apple.com>

3 files changed, 47 insertions, 42 deletions

diff --git a/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/generic_category.pass.cpp b/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/generic_category.pass.cpp
index 068202c..d4bbde7 100644
--- a/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/generic_category.pass.cpp
+++ b/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/generic_category.pass.cpp
@@ -44,14 +44,19 @@ int main(int, char**)
         errno = E2BIG; // something that message will never generate
         const std::error_category& e_cat1 = std::generic_category();
         const std::string msg = e_cat1.message(-1);
-        // Exact message format varies by platform.
-#if defined(_AIX)
-        LIBCPP_ASSERT(msg.rfind("Error -1 occurred", 0) == 0);
-#elif defined(_NEWLIB_VERSION)
-        LIBCPP_ASSERT(msg.empty());
-#else
-        LIBCPP_ASSERT(msg.rfind("Unknown error", 0) == 0);
+        // Exact message format varies by platform.  We can't detect
+        // some of these (Musl in particular) using the preprocessor,
+        // so accept a few sensible messages.  Newlib unfortunately
+        // responds with an empty message, which we probably want to
+        // treat as a failure code otherwise, but we can detect that
+        // with the preprocessor.
+        LIBCPP_ASSERT(msg.rfind("Error -1 occurred", 0) == 0       // AIX
+                      || msg.rfind("No error information", 0) == 0 // Musl
+                      || msg.rfind("Unknown error", 0) == 0        // Glibc
+#if defined(_NEWLIB_VERSION)
+                      || msg.empty()
 #endif
+        );
         assert(errno == E2BIG);
     }
 
diff --git a/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/system_category.pass.cpp b/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/system_category.pass.cpp
index 42fdd1c..eefbddd 100644
--- a/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/system_category.pass.cpp
+++ b/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/system_category.pass.cpp
@@ -50,14 +50,19 @@ int main(int, char**) {
     errno                             = E2BIG; // something that message will never generate
     const std::error_category& e_cat1 = std::system_category();
     const std::string msg             = e_cat1.message(-1);
-    // Exact message format varies by platform.
-#if defined(_AIX)
-    LIBCPP_ASSERT(msg.rfind("Error -1 occurred", 0) == 0);
-#elif defined(_NEWLIB_VERSION)
-    LIBCPP_ASSERT(msg.empty());
-#else
-    LIBCPP_ASSERT(msg.rfind("Unknown error", 0) == 0);
+    // Exact message format varies by platform.  We can't detect
+    // some of these (Musl in particular) using the preprocessor,
+    // so accept a few sensible messages.  Newlib unfortunately
+    // responds with an empty message, which we probably want to
+    // treat as a failure code otherwise, but we can detect that
+    // with the preprocessor.
+    LIBCPP_ASSERT(msg.rfind("Error -1 occurred", 0) == 0       // AIX
+                  || msg.rfind("No error information", 0) == 0 // Musl
+                  || msg.rfind("Unknown error", 0) == 0        // Glibc
+#if defined(_NEWLIB_VERSION)
+                  || msg.empty()
 #endif
+    );
     assert(errno == E2BIG);
   }
 
diff --git a/libcxx/test/std/localization/locale.categories/category.numeric/locale.nm.put/facet.num.put.members/put_long_double.pass.cpp b/libcxx/test/std/localization/locale.categories/category.numeric/locale.nm.put/facet.num.put.members/put_long_double.pass.cpp
index 8637a93..16e4ea7 100644
--- a/libcxx/test/std/localization/locale.categories/category.numeric/locale.nm.put/facet.num.put.members/put_long_double.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.numeric/locale.nm.put/facet.num.put.members/put_long_double.pass.cpp
@@ -13,15 +13,11 @@
 // iter_type put(iter_type s, ios_base& iob, char_type fill, long double v) const;
 
 // XFAIL: win32-broken-printf-g-precision
-// XFAIL: LIBCXX-PICOLIBC-FIXME
-
-// Needs more investigation, but this is probably failing on Android M (API 23)
-// and up because the printf formatting of NAN changed.
-// XFAIL: LIBCXX-ANDROID-FIXME && !android-device-api={{21|22}}
 
 #include <locale>
 #include <ios>
 #include <cassert>
+#include <cstdio>
 #include <streambuf>
 #include <cmath>
 #include "test_macros.h"
@@ -8934,11 +8930,10 @@ void test4()
     char str[200];
     std::locale lc = std::locale::classic();
     std::locale lg(lc, new my_numpunct);
-#ifdef _AIX
-    std::string inf = "INF";
-#else
-    std::string inf = "inf";
-#endif
+
+    // This should match the underlying C library
+    std::snprintf(str, sizeof(str), "%f", INFINITY);
+    std::string inf = str;
 
     const my_facet f(1);
     {
@@ -10727,24 +10722,24 @@ void test5()
     std::locale lc = std::locale::classic();
     std::locale lg(lc, new my_numpunct);
     const my_facet f(1);
-#if defined(_AIX)
-    std::string nan= "NaNQ";
-    std::string NaN = "NaNQ";
-    std::string nan_padding25 = "*********************";
-    std::string pnan_sign = "+";
-    std::string pnan_padding25 = "********************";
-#else
-    std::string nan= "nan";
-    std::string NaN = "NAN";
-    std::string nan_padding25 = "**********************";
-#if defined(TEST_HAS_GLIBC) || defined(_WIN32)
-    std::string pnan_sign = "+";
-    std::string pnan_padding25 = "*********************";
-#else
-    std::string pnan_sign = "";
-    std::string pnan_padding25 = "**********************";
-#endif
-#endif
+
+    // The output here depends on the underlying C library, so work out what
+    // that does.
+    std::snprintf(str, sizeof(str), "%f", std::nan(""));
+    std::string nan = str;
+
+    std::snprintf(str, sizeof(str), "%F", std::nan(""));
+    std::string NaN = str;
+
+    std::snprintf(str, sizeof(str), "%+f", std::nan(""));
+    std::string pnan_sign;
+    if (str[0] == '+') {
+      pnan_sign = "+";
+    }
+
+    std::string nan_padding25  = std::string(25 - nan.length(), '*');
+    std::string pnan_padding25 = std::string(25 - nan.length() - pnan_sign.length(), '*');
+
     {
         long double v = std::nan("");
         std::ios ios(0);