[flang-commits] [flang] [flang] fix flang builds with clang 20 after #100692 (PR #106718)

[via flang-commits]

https://github.com/jeanPerier created https://github.com/llvm/llvm-project/pull/106718

#100692 changes clang template deduction, and an error was now emitted when building flang with top of the tree clang when mapping std::pow in intrinsics-library.cpp for constant folding `error: address of overloaded function 'pow' is ambiguous`

See https://lab.llvm.org/buildbot/#/builders/4/builds/1670

I I am not expert enough to understand if the new error is justified or not here, but it is easy to help the compiler here with explicit wrappers to fix the builds.


>From 938052d9dad2760898571ec3e2089431601efd19 Mon Sep 17 00:00:00 2001
From: Jean Perier <jperier at nvidia.com>
Date: Fri, 30 Aug 2024 05:20:42 -0700
Subject: [PATCH] [flang] fix flang build with clang 20 after #100692

---
 flang/lib/Evaluate/intrinsics-library.cpp | 25 ++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/flang/lib/Evaluate/intrinsics-library.cpp b/flang/lib/Evaluate/intrinsics-library.cpp
index 65636b9956e780..ed28d8130808fa 100644
--- a/flang/lib/Evaluate/intrinsics-library.cpp
+++ b/flang/lib/Evaluate/intrinsics-library.cpp
@@ -255,6 +255,25 @@ struct HostRuntimeLibrary<HostT, LibraryVersion::Libm> {
   static constexpr HostRuntimeMap map{table};
   static_assert(map.Verify(), "map must be sorted");
 };
+
+// Helpers to map complex std::pow whose resolution in F2{std::pow} is
+// ambiguous as of clang++ 20.
+template <typename HostT>
+static std::complex<HostT> StdPowF2(
+    const std::complex<HostT> &x, const std::complex<HostT> &y) {
+  return std::pow(x, y);
+}
+template <typename HostT>
+static std::complex<HostT> StdPowF2A(
+    const HostT &x, const std::complex<HostT> &y) {
+  return std::pow(x, y);
+}
+template <typename HostT>
+static std::complex<HostT> StdPowF2B(
+    const std::complex<HostT> &x, const HostT &y) {
+  return std::pow(x, y);
+}
+
 template <typename HostT>
 struct HostRuntimeLibrary<std::complex<HostT>, LibraryVersion::Libm> {
   using F = FuncPointer<std::complex<HostT>, const std::complex<HostT> &>;
@@ -275,9 +294,9 @@ struct HostRuntimeLibrary<std::complex<HostT>, LibraryVersion::Libm> {
       FolderFactory<F, F{std::cosh}>::Create("cosh"),
       FolderFactory<F, F{std::exp}>::Create("exp"),
       FolderFactory<F, F{std::log}>::Create("log"),
-      FolderFactory<F2, F2{std::pow}>::Create("pow"),
-      FolderFactory<F2A, F2A{std::pow}>::Create("pow"),
-      FolderFactory<F2B, F2B{std::pow}>::Create("pow"),
+      FolderFactory<F2, F2{StdPowF2}>::Create("pow"),
+      FolderFactory<F2A, F2A{StdPowF2A}>::Create("pow"),
+      FolderFactory<F2B, F2B{StdPowF2B}>::Create("pow"),
       FolderFactory<F, F{std::sin}>::Create("sin"),
       FolderFactory<F, F{std::sinh}>::Create("sinh"),
       FolderFactory<F, F{std::sqrt}>::Create("sqrt"),