[committed] libstdc++: Fix std::format("{:F}", inf) to use uppercase

[Jonathan Wakely <jwakely@redhat.com>]

Tested x86_64-linux. Pushed to trunk. Backport to gcc-13 will follow.

-- >8 --

std::format was treating {:f} and {:F} identically on the basis that for
the fixed 1.234567 format there are no alphabetical characters that need
to be in uppercase. But that's wrong for infinities and NaNs, which
should be formatted as "INF" and "NAN" for {:F}.

libstdc++-v3/ChangeLog:

	* include/std/format (__format::_Pres_type): Add _Pres_F.
	(__formatter_fp::parse): Use _Pres_F for 'F'.
	(__formatter_fp::format): Set __upper for _Pres_F.
	* testsuite/std/format/functions/format.cc: Check formatting of
	infinity and NaN for each presentation type.
---
 libstdc++-v3/include/std/format                      | 10 ++++++++--
 .../testsuite/std/format/functions/format.cc         | 12 ++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index a8db10d6460..40c7d6128f6 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -309,7 +309,7 @@ namespace __format
     // Presentation types for integral types (including bool and charT).
     _Pres_d = 1, _Pres_b, _Pres_B, _Pres_o, _Pres_x, _Pres_X, _Pres_c,
     // Presentation types for floating-point types.
-    _Pres_a = 1, _Pres_A, _Pres_e, _Pres_E, _Pres_f, _Pres_g, _Pres_G,
+    _Pres_a = 1, _Pres_A, _Pres_e, _Pres_E, _Pres_f, _Pres_F, _Pres_g, _Pres_G,
     _Pres_p = 0, _Pres_P,   // For pointers.
     _Pres_s = 0,            // For strings and bool.
     _Pres_esc = 0xf,        // For strings and charT.
@@ -1382,10 +1382,13 @@ namespace __format
 	    ++__first;
 	    break;
 	  case 'f':
-	  case 'F':
 	    __spec._M_type = _Pres_f;
 	    ++__first;
 	    break;
+	  case 'F':
+	    __spec._M_type = _Pres_F;
+	    ++__first;
+	    break;
 	  case 'g':
 	    __spec._M_type = _Pres_g;
 	    ++__first;
@@ -1442,6 +1445,9 @@ namespace __format
 	      __use_prec = true;
 	      __fmt = chars_format::scientific;
 	      break;
+	    case _Pres_F:
+	      __upper = true;
+	      [[fallthrough]];
 	    case _Pres_f:
 	      __use_prec = true;
 	      __fmt = chars_format::fixed;
diff --git a/libstdc++-v3/testsuite/std/format/functions/format.cc b/libstdc++-v3/testsuite/std/format/functions/format.cc
index 4db5202815d..59ed3be8baa 100644
--- a/libstdc++-v3/testsuite/std/format/functions/format.cc
+++ b/libstdc++-v3/testsuite/std/format/functions/format.cc
@@ -159,6 +159,18 @@ test_alternate_forms()
   VERIFY( s == "1.e+01 1.e+01 1.e+01" );
 }
 
+void
+test_infnan()
+{
+  double inf = std::numeric_limits<double>::infinity();
+  double nan = std::numeric_limits<double>::quiet_NaN();
+  std::string s;
+  s = std::format("{0} {0:e} {0:E} {0:f} {0:F} {0:g} {0:G} {0:a} {0:A}", inf);
+  VERIFY( s == "inf inf INF inf INF inf INF inf INF" );
+  s = std::format("{0} {0:e} {0:E} {0:f} {0:F} {0:g} {0:G} {0:a} {0:A}", nan);
+  VERIFY( s == "nan nan NAN nan NAN nan NAN nan NAN" );
+}
+
 struct euro_punc : std::numpunct<char>
 {
   std::string do_grouping() const override { return "\3\3"; }
-- 
2.41.0