libgfortran: EN0.0E0 and ES0.0E0 format editing.

F2018 and F2023 standards added zero width exponents. This required
additional special handing in the process of building formatted
floating point strings.

G formatting uses either F or E formatting as documented in
write_float.def comments. This logic changes the format token from FMT_G
to FMT_F or FMT_E. The new formatting requirements interfere with this
process when a FMT_G float string is being built.  To avoid this, a new
component called 'pushed' is added to the fnode structure to save this
condition.  The 'pushed' condition is then used to bypass portions of
the new ES,E,EN, and D formatting, falling through to the existing
default formatting which is retained.

libgfortran/ChangeLog:
	PR libfortran/111022
	* io/format.c (get_fnode): Update initialization of fnode.
	(parse_format_list): Initialization.
	* io/format.h (struct fnode): Added the new 'pushed' component.
	* io/write.c (select_buffer): Whitespace.
	(write_real): Whitespace.
	(write_real_w0): Adjust logic for the d == 0 condition.
	* io/write_float.def (determine_precision): Whitespace.
	(build_float_string): Calculate width of ..E0 exponents and
	adjust logic accordingly.
	(build_infnan_string): Whitespace.
	(CALCULATE_EXP): Whitespace.
	(quadmath_snprintf): Whitespace.
	(determine_en_precision): Whitespace.

gcc/testsuite/ChangeLog:
	PR libfortran/111022
	* gfortran.dg/fmt_error_10.f: Show D+0 exponent.
	* gfortran.dg/pr96436_4.f90: Show E+0 exponent.
	* gfortran.dg/pr96436_5.f90: Show E+0 exponent.
	* gfortran.dg/pr111022.f90: New test.

4 files changed, 77 insertions, 5 deletions

diff --git a/gcc/testsuite/gfortran.dg/fmt_error_10.f b/gcc/testsuite/gfortran.dg/fmt_error_10.f
index 6e1a5f6..fc6620a 100644
--- a/gcc/testsuite/gfortran.dg/fmt_error_10.f
+++ b/gcc/testsuite/gfortran.dg/fmt_error_10.f
@@ -18,7 +18,7 @@
 
       str = '(1pd0.15)'
       write (line,str,iostat=istat, iomsg=msg) 1.0d0
-      if (line.ne."1.000000000000000") STOP 5
+      if (line.ne."1.000000000000000D+0") STOP 5
       read (*,str,iostat=istat, iomsg=msg) x
       if (istat.ne.5006 .or. msg(1:10).ne."Zero width") STOP 6
       if (x.ne.555.25) STOP 7
diff --git a/gcc/testsuite/gfortran.dg/pr111022.f90 b/gcc/testsuite/gfortran.dg/pr111022.f90
new file mode 100644
index 0000000..eef55ff
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr111022.f90
@@ -0,0 +1,72 @@
+! { dg-do run }
+program pr111022
+  character(20) :: buffer
+  write(buffer,"(EN0.3E0)") .6660_4
+  if (buffer.ne."666.000E-3") stop 1
+  write(buffer,"(EN0.3E0)") 6.660_4
+  if (buffer.ne."6.660E+0") stop 2
+  write(buffer,"(EN0.3E0)") 66.60_4
+  if (buffer.ne."66.600E+0") stop 3
+  write(buffer,"(EN0.3E0)") 666.0_4
+  if (buffer.ne."666.000E+0") stop 4
+  write(buffer,"(EN0.3E0)") 6660.0_4
+  if (buffer.ne."6.660E+3") stop 5
+  write(buffer,"(EN0.3E0)") 66600.0_4
+  if (buffer.ne."66.600E+3") stop 6
+  
+  write(buffer,"(EN0.0E0)") 666.0_4
+  if (buffer.ne."666.E+0") stop 7
+  write(buffer,"(EN0.0E1)") 666.0_4
+  if (buffer.ne."666.E+0") stop 8
+  write(buffer,"(EN0.0E2)") 666.0_4
+  if (buffer.ne."666.E+00") stop 9
+  write(buffer,"(EN0.0E3)") 666.0_4
+  if (buffer.ne."666.E+000") stop 10
+  write(buffer,"(EN0.0E4)") 666.0_4
+  if (buffer.ne."666.E+0000") stop 11
+  write(buffer,"(EN0.0E5)") 666.0_4
+  if (buffer.ne."666.E+00000") stop 12
+  write(buffer,"(EN0.0E6)") 666.0_4
+  if (buffer.ne."666.E+000000") stop 13
+  
+  write(buffer,"(ES0.3E0)") .6660_4
+  if (buffer.ne."6.660E-1") stop 14
+  write(buffer,"(ES0.3E0)") 6.660_4
+  if (buffer.ne."6.660E+0") stop 15
+  write(buffer,"(ES0.3E0)") 66.60_4
+  if (buffer.ne."6.660E+1") stop 16
+  write(buffer,"(ES0.3E0)") 666.0_4
+  if (buffer.ne."6.660E+2") stop 17
+  write(buffer,"(ES0.3E0)") 6660.0_4
+  if (buffer.ne."6.660E+3") stop 18
+  write(buffer,"(ES0.3E0)") 66600.0_4
+  if (buffer.ne."6.660E+4") stop 19
+  
+  write(buffer,"(ES0.0E0)") 666.0_4
+  if (buffer.ne."7.E+2") stop 20
+  write(buffer,"(ES0.0E1)") 666.0_4
+  if (buffer.ne."7.E+2") stop 21
+  write(buffer,"(ES0.0E2)") 666.0_4
+  if (buffer.ne."7.E+02") stop 22
+  write(buffer,"(ES0.0E3)") 666.0_4
+  if (buffer.ne."7.E+002") stop 23
+  write(buffer,"(ES0.0E4)") 666.0_4
+  if (buffer.ne."7.E+0002") stop 24
+  write(buffer,"(ES0.0E5)") 666.0_4
+  if (buffer.ne."7.E+00002") stop 25
+  write(buffer,"(ES0.0E6)") 666.0_4
+  if (buffer.ne."7.E+000002") stop 26
+  
+  write(buffer,"(E0.3E0)") .6660_4
+  if (buffer.ne."0.666E+0") stop 27
+  write(buffer,"(E0.3)") .6660_4
+  if (buffer.ne."0.666E+0") stop 28
+  write(buffer,"(E0.1E0)") .6660_4
+  if (buffer.ne."0.7E+0") stop 29
+  write(buffer,"(E0.1)") .6660_4
+  if (buffer.ne."0.7E+0") stop 30
+  write(buffer,"(E0.5E0)") .6660_4
+  if (buffer.ne."0.66600E+0") stop 31
+  write(buffer,"(E0.5)") .6660_4
+  if (buffer.ne."0.66600E+0") stop 32
+end program pr111022
diff --git a/gcc/testsuite/gfortran.dg/pr96436_4.f90 b/gcc/testsuite/gfortran.dg/pr96436_4.f90
index 335ce5f..7d2cfef 100644
--- a/gcc/testsuite/gfortran.dg/pr96436_4.f90
+++ b/gcc/testsuite/gfortran.dg/pr96436_4.f90
@@ -17,9 +17,9 @@ write(buffer,fmt) ">", 3.0, "<"
 if (buffer.ne.">0.30E+1<") stop 4
 fmt = "(1a1,en0.2,1a1)"
 write(buffer,fmt) ">", 3.0, "<"
-if (buffer.ne.">3.00<") stop 5
+if (buffer.ne.">3.00E+0<") stop 5
 fmt = "(1a1,es0.2,1a1)"
 write(buffer,fmt) ">", 3.0, "<"
-if (buffer.ne.">3.00<") stop 6
+if (buffer.ne.">3.00E+0<") stop 6
 end
 
diff --git a/gcc/testsuite/gfortran.dg/pr96436_5.f90 b/gcc/testsuite/gfortran.dg/pr96436_5.f90
index a45df89..3870d98 100644
--- a/gcc/testsuite/gfortran.dg/pr96436_5.f90
+++ b/gcc/testsuite/gfortran.dg/pr96436_5.f90
@@ -17,9 +17,9 @@ write(buffer,fmt) ">", 3.0, "<"
 if (buffer.ne.">0.30E+1<") stop 4
 fmt = "(1a1,en0.2,1a1)"
 write(buffer,fmt) ">", 3.0, "<"
-if (buffer.ne.">3.00<") stop 5
+if (buffer.ne.">3.00E+0<") stop 5
 fmt = "(1a1,es0.2,1a1)"
 write(buffer,fmt) ">", 3.0, "<"
-if (buffer.ne.">3.00<") stop 6
+if (buffer.ne.">3.00E+0<") stop 6
 end