[gcc r14-3283] libstdc++: Fix std::format("{:F}", inf) to use uppercase

[gcc r14-3283] libstdc++: Fix std::format("{:F}", inf) to use uppercase

[Jonathan Wakely]

https://gcc.gnu.org/g:d07bce478f9d770de5acb0480a3f0cec2f8b72d8

commit r14-3283-gd07bce478f9d770de5acb0480a3f0cec2f8b72d8
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Aug 17 13:02:27 2023 +0100

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

Diff:
---
 libstdc++-v3/include/std/format                       | 10 ++++++++--
 libstdc++-v3/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 a8db10d6460c..40c7d6128f60 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 4db5202815d6..59ed3be8baa3 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"; }