Fortran: Use _Float128 rather than __float128 for c_float128 kind.

The GNU Fortran manual documents that the c_float128 kind corresponds
to __float128, but in fact the implementation uses float128_type_node,
which is _Float128.  Both refer to the 128-bit IEEE/ISO encoding, but
some targets including aarch64 only define _Float128 and not __float128,
and do not provide quadmath.h.  This caused errors in some test cases
referring to __float128.

This patch changes the documentation (including code comments) and
test cases to use _Float128 to match the implementation.

2021-09-16  Sandra Loosemore  <sandra@codesourcery.com>

gcc/fortran/

	* intrinsic.texi (ISO_C_BINDING): Change C_FLOAT128 to correspond
	to _Float128 rather than __float128.
	* iso-c-binding.def (c_float128): Update comments.
	* trans-intrinsic.c (gfc_builtin_decl_for_float_kind): Likewise.
	(build_round_expr): Likewise.
	(gfc_build_intrinsic_lib_fndcecls): Likewise.
	* trans-types.h (gfc_real16_is_float128): Likewise.

gcc/testsuite/
	* gfortran.dg/PR100914.c: Do not include quadmath.h.  Use
	_Float128 _Complex instead of __complex128.
	* gfortran.dg/PR100914.f90: Add -Wno-pedantic to suppress error
	about use of _Float128.
	* gfortran.dg/c-interop/typecodes-array-float128-c.c: Use
	_Float128 instead of __float128.
	* gfortran.dg/c-interop/typecodes-sanity-c.c: Likewise.
	* gfortran.dg/c-interop/typecodes-scalar-float128-c.c: Likewise.
	* lib/target-supports.exp
	(check_effective_target_fortran_real_c_float128): Update comments.

libgfortran/
	* ISO_Fortran_binding.h: Update comments.
	* runtime/ISO_Fortran_binding.c: Likewise.

6 files changed, 12 insertions, 13 deletions

diff --git a/gcc/testsuite/gfortran.dg/PR100914.c b/gcc/testsuite/gfortran.dg/PR100914.c
index c6bd973..ea339e7 100644
--- a/gcc/testsuite/gfortran.dg/PR100914.c
+++ b/gcc/testsuite/gfortran.dg/PR100914.c
@@ -5,7 +5,6 @@
 #include <stdbool.h>
 #include <stdio.h>
 #include <math.h>
-#include <quadmath.h>
 
 #include <ISO_Fortran_binding.h>
 
@@ -29,7 +28,7 @@
 #define CMPLXL(x, y) ((long double complex)((long double)(x) + (long double complex)I * (long double)(y)))
 
 #undef CMPLX
-#define CMPLX(x, y) ((__complex128 )((double)(x) + (double complex)I * (double)(y)))
+#define CMPLX(x, y) ((_Float128 _Complex )((double)(x) + (double complex)I * (double)(y)))
 
 #define N 11
 #define M 7
@@ -37,7 +36,7 @@
 typedef float _Complex c_float_complex;
 typedef double _Complex c_double_complex;
 typedef long double _Complex c_long_double_complex;
-typedef __complex128 c_float128_complex;
+typedef _Float128 _Complex c_float128_complex;
 
 bool c_vrfy_c_float_complex (const CFI_cdesc_t *restrict);
 
diff --git a/gcc/testsuite/gfortran.dg/PR100914.f90 b/gcc/testsuite/gfortran.dg/PR100914.f90
index 64b3335..d8057fd 100644
--- a/gcc/testsuite/gfortran.dg/PR100914.f90
+++ b/gcc/testsuite/gfortran.dg/PR100914.f90
@@ -2,6 +2,7 @@
 ! { dg-do run { xfail { { x86_64*-*-* i?86*-*-* } && longdouble128 } } }
 ! { dg-additional-sources PR100914.c }
 ! { dg-require-effective-target fortran_real_c_float128 }
+! { dg-additional-options "-Wno-pedantic" }
 !
 ! Test the fix for PR100914
 ! 
diff --git a/gcc/testsuite/gfortran.dg/c-interop/typecodes-array-float128-c.c b/gcc/testsuite/gfortran.dg/c-interop/typecodes-array-float128-c.c
index d081feb..4fcb6e2 100644
--- a/gcc/testsuite/gfortran.dg/c-interop/typecodes-array-float128-c.c
+++ b/gcc/testsuite/gfortran.dg/c-interop/typecodes-array-float128-c.c
@@ -32,7 +32,7 @@ void
 ctest (CFI_cdesc_t *arg_float128,
        CFI_cdesc_t *arg_complex128)
 {
-  check (arg_float128, sizeof (__float128), CFI_type_float128);
-  check (arg_complex128, sizeof (__float128) * 2,
+  check (arg_float128, sizeof (_Float128), CFI_type_float128);
+  check (arg_complex128, sizeof (_Float128) * 2,
 	 CFI_type_float128_Complex);
 }
diff --git a/gcc/testsuite/gfortran.dg/c-interop/typecodes-sanity-c.c b/gcc/testsuite/gfortran.dg/c-interop/typecodes-sanity-c.c
index a1d044b..90f0b20 100644
--- a/gcc/testsuite/gfortran.dg/c-interop/typecodes-sanity-c.c
+++ b/gcc/testsuite/gfortran.dg/c-interop/typecodes-sanity-c.c
@@ -23,8 +23,7 @@ static struct tc_info tc_table[] =
 {
   /* Extension types.
      Note there is no portable C equivalent type for CFI_type_ucs4_char type
-     (4-byte Unicode characters), and GCC rejects "__float128 _Complex",
-     so this is kind of hacky...  */
+     (4-byte Unicode characters), so this is kind of hacky...  */
 #if CFI_type_int128_t > 0
   { CFI_type_int128_t, "CFI_type_int128_t",
     sizeof (__int128), 1 },
@@ -38,9 +37,9 @@ static struct tc_info tc_table[] =
 #endif
 #if CFI_type_float128 > 0  
   { CFI_type_float128, "CFI_type_float128",
-    sizeof (__float128), 1 },
+    sizeof (_Float128), 1 },
   { CFI_type_float128_Complex, "CFI_type_float128_Complex",
-    sizeof (__float128) * 2, 1 },
+    sizeof (_Float128 _Complex), 1 },
 #endif
 #if CFI_type_cfunptr > 0  
   { CFI_type_cfunptr, "CFI_type_cfunptr",
diff --git a/gcc/testsuite/gfortran.dg/c-interop/typecodes-scalar-float128-c.c b/gcc/testsuite/gfortran.dg/c-interop/typecodes-scalar-float128-c.c
index f1833aa..7eafa93 100644
--- a/gcc/testsuite/gfortran.dg/c-interop/typecodes-scalar-float128-c.c
+++ b/gcc/testsuite/gfortran.dg/c-interop/typecodes-scalar-float128-c.c
@@ -31,8 +31,8 @@ void
 ctest (CFI_cdesc_t *arg_float128,
        CFI_cdesc_t *arg_complex128)
 {
-  check (arg_float128, sizeof (__float128), CFI_type_float128);
-  check (arg_complex128, sizeof (__float128) * 2,
+  check (arg_float128, sizeof (_Float128), CFI_type_float128);
+  check (arg_complex128, sizeof (_Float128) * 2,
 	 CFI_type_float128_Complex);
 }
 
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 8697ceb..f11c4e6 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -1578,8 +1578,8 @@ proc check_effective_target_fortran_real_10 { } {
 
 # Return 1 if the target supports Fortran real kind C_FLOAT128,
 # 0 otherwise.  This differs from check_effective_target_fortran_real_16
-# because __float128 has the additional requirement that it be the
-# 128-bit IEEE encoding; even if __float128 is available in C, it may not
+# because _Float128 has the additional requirement that it be the
+# 128-bit IEEE encoding; even if _Float128 is available in C, it may not
 # have a corresponding Fortran kind on targets (PowerPC) that use some 
 # other encoding for long double/TFmode/real(16).
 proc check_effective_target_fortran_real_c_float128 { } {