From 0631e008adc759cc801d0d034224ee6b4bcf31aa Mon Sep 17 00:00:00 2001
From: Steve Kargl <sgk@troutmask.apl.washington.edu>
Date: Fri, 12 Feb 2021 07:58:16 -0800
Subject: [PATCH] libgfortran: Fix PR95647 by changing the interfaces of
 operators .eq. and .ne.

The FE converts the old school .eq. to ==,
and then tracks the ==.  The module starts with == and so it does not
properly overload the .eq.  Reversing the interfaces fixes this.

2021-02-12  Steve Kargl <sgk@troutmask.apl.washington.edu>

libgfortran/ChangeLog:

	PR libfortran/95647
	* ieee/ieee_arithmetic.F90: Flip interfaces of operators .eq. to
	== and .ne. to /= .

gcc/testsuite/ChangeLog:

	PR libfortran/95647
	* gfortran.dg/ieee/ieee_12.f90: New test.
---
 gcc/testsuite/gfortran.dg/ieee/ieee_12.f90 | 24 ++++++++++++++++++++++
 libgfortran/ieee/ieee_arithmetic.F90       |  9 ++++----
 2 files changed, 29 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/gfortran.dg/ieee/ieee_12.f90

diff --git a/gcc/testsuite/gfortran.dg/ieee/ieee_12.f90 b/gcc/testsuite/gfortran.dg/ieee/ieee_12.f90
new file mode 100644
index 00000000000..139a70142b8
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/ieee/ieee_12.f90
@@ -0,0 +1,24 @@
+! { dg-do run }
+! PR95647 operator(.eq.) and operator(==) treated differently
+program test
+  use, intrinsic :: ieee_arithmetic, only :                 &
+&                ieee_class,                                       &
+&                ieee_class_type,                                  &
+&                ieee_negative_normal,                             &
+&                ieee_positive_normal,                             &
+&                operator(.eq.), operator(.ne.)
+  integer :: good
+  real(4) r4
+  type(ieee_class_type) class1
+  good = 0
+  r4 = 1.0
+  class1 = ieee_class(r4)
+  if (class1 .eq. ieee_positive_normal) good = good + 1
+  if (class1 .ne. ieee_negative_normal) good = good + 1
+  r4 = -1.0
+  class1 = ieee_class(r4)
+  if (class1 .eq. ieee_negative_normal) good = good + 1
+  if (class1 .ne. ieee_positive_normal) good = good + 1
+  if (good /= 4) call abort
+end program test
+
diff --git a/libgfortran/ieee/ieee_arithmetic.F90 b/libgfortran/ieee/ieee_arithmetic.F90
index 55992232ce2..35a16938f8e 100644
--- a/libgfortran/ieee/ieee_arithmetic.F90
+++ b/libgfortran/ieee/ieee_arithmetic.F90
@@ -77,15 +77,16 @@ module IEEE_ARITHMETIC
 
 
   ! Equality operators on the derived types
-  interface operator (==)
+  ! Note, the FE overloads .eq. to == and .ne. to /=
+  interface operator (.eq.)
     module procedure IEEE_CLASS_TYPE_EQ, IEEE_ROUND_TYPE_EQ
   end interface
-  public :: operator(==)
+  public :: operator(.eq.)
 
-  interface operator (/=)
+  interface operator (.ne.)
     module procedure IEEE_CLASS_TYPE_NE, IEEE_ROUND_TYPE_NE
   end interface
-  public :: operator (/=)
+  public :: operator (.ne.)
 
 
   ! IEEE_IS_FINITE
-- 
2.30.2