Make hex float test more stable on different libc (fmtlib#3762)

Signed-off-by: Vladislav Shchapov <[email protected]>

test/format-test.cc

@@ -1361,14 +1361,11 @@ TEST(format_test, format_double) {
   EXPECT_EQ(fmt::format("{0:e}", 392.65), "3.926500e+02");
   EXPECT_EQ(fmt::format("{0:E}", 392.65), "3.926500E+02");
   EXPECT_EQ(fmt::format("{0:+010.4g}", 392.65), "+0000392.6");
-  char buffer[buffer_size];
 
 #if FMT_CPLUSPLUS >= 201703L
   double xd = 0x1.ffffffffffp+2;
-  safe_sprintf(buffer, "%.*a", 10, xd);
-  EXPECT_EQ(fmt::format("{:.10a}", xd), buffer);
-  safe_sprintf(buffer, "%.*a", 9, xd);
-  EXPECT_EQ(fmt::format("{:.9a}", xd), buffer);
+  EXPECT_EQ(fmt::format("{:.10a}", xd), "0x1.ffffffffffp+2");
+  EXPECT_EQ(fmt::format("{:.9a}", xd), "0x2.000000000p+2");
 
   if (std::numeric_limits<long double>::digits == 64) {
     auto ld = 0xf.ffffffffffp-3l;
@@ -1384,8 +1381,7 @@ TEST(format_test, format_double) {
     EXPECT_EQ(fmt::format("{:#a}", d), "0x1.p-1022");
 
     d = (std::numeric_limits<double>::max)();
-    safe_sprintf(buffer, "%a", d);
-    EXPECT_EQ(fmt::format("{:a}", d), buffer);
+    EXPECT_EQ(fmt::format("{:a}", d), "0x1.fffffffffffffp+1023");
 
     d = std::numeric_limits<double>::denorm_min();
     EXPECT_EQ(fmt::format("{:a}", d), "0x0.0000000000001p-1022");
@@ -1402,8 +1398,7 @@ TEST(format_test, format_double) {
     EXPECT_EQ(fmt::format("{:a}", ld), "0x0.000000000000001p-16382");
   }
 
-  safe_sprintf(buffer, "%.*a", 10, 4.2);
-  EXPECT_EQ(fmt::format("{:.10a}", 4.2), buffer);
+  EXPECT_EQ(fmt::format("{:.10a}", 4.2), "0x1.0ccccccccdp+2");
 
   EXPECT_EQ(fmt::format("{:a}", -42.0), "-0x1.5p+5");
   EXPECT_EQ(fmt::format("{:A}", -42.0), "-0X1.5P+5");