From 08bfc002885f874afb1e58814c27e2c461aa8130 Mon Sep 17 00:00:00 2001
From: Peter Klausler <pklausler@nvidia.com>
Date: Thu, 29 Jun 2023 14:22:30 -0700
Subject: [PATCH] [flang] Don't warn about a NaN argument to ISNAN()

Don't emit a warning when a compile-time constant argument to
ISNAN() or IEEE_IS_NAN() is a NaN.

Differential Revision: https://reviews.llvm.org/D154377
---
 flang/lib/Evaluate/fold-logical.cpp |  3 ++-
 flang/test/Evaluate/errors01.f90    | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/flang/lib/Evaluate/fold-logical.cpp b/flang/lib/Evaluate/fold-logical.cpp
index e900905..129a8fc 100644
--- a/flang/lib/Evaluate/fold-logical.cpp
+++ b/flang/lib/Evaluate/fold-logical.cpp
@@ -155,10 +155,11 @@ Expr<Type<TypeCategory::Logical, KIND>> FoldIntrinsicFunction(
       }
     }
   } else if (name == "isnan" || name == "__builtin_ieee_is_nan") {
-    using DefaultReal = Type<TypeCategory::Real, 4>;
     // Only replace the type of the function if we can do the fold
     if (args[0] && args[0]->UnwrapExpr() &&
         IsActuallyConstant(*args[0]->UnwrapExpr())) {
+      auto restorer{context.messages().DiscardMessages()};
+      using DefaultReal = Type<TypeCategory::Real, 4>;
       return FoldElementalIntrinsic<T, DefaultReal>(context, std::move(funcRef),
           ScalarFunc<T, DefaultReal>([](const Scalar<DefaultReal> &x) {
             return Scalar<T>{x.IsNotANumber()};
diff --git a/flang/test/Evaluate/errors01.f90 b/flang/test/Evaluate/errors01.f90
index cbb05ff..6f1f056 100644
--- a/flang/test/Evaluate/errors01.f90
+++ b/flang/test/Evaluate/errors01.f90
@@ -176,7 +176,21 @@ module m
     integer, parameter :: bad4 = dim(huge(1),-1)
     !CHECK: warning: HYPOT intrinsic folding overflow
     real, parameter :: bad5 = hypot(huge(0.), huge(0.))
+    !CHECK: warning: SUM() of INTEGER(4) data overflowed
+    integer, parameter :: bad6 = sum([huge(1),huge(1)])
+    !CHECK: warning: SUM() of REAL(4) data overflowed
+    real, parameter :: bad7 = sum([huge(1.),huge(1.)])
+    !CHECK: warning: SUM() of COMPLEX(4) data overflowed
+    complex, parameter :: bad8 = sum([(huge(1.),0.),(huge(1.),0.)])
+    !CHECK: warning: PRODUCT() of INTEGER(4) data overflowed
+    integer, parameter :: bad9 = product([huge(1),huge(1)])
+    !CHECK: warning: PRODUCT() of REAL(4) data overflowed
+    real, parameter :: bad10 = product([huge(1.),huge(1.)])
+    !CHECK: warning: PRODUCT() of COMPLEX(4) data overflowed
+    complex, parameter :: bad11 = product([(huge(1.),0.),(huge(1.),0.)])
     !CHECK: warning: overflow on REAL(8) to REAL(4) conversion
     x = 1.D40
+    !CHECK-NOT: warning: invalid argument
+    if (.not. isnan(real(z'ffffffffffffffff',8))) stop
   end subroutine
 end module
-- 
2.7.4