From 95abfcbe51b2896e0e2b30aaf014059be49cbad6 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Fri, 15 May 2026 14:55:33 -0400
Subject: [PATCH] LLVMFlang: Add support for MSVC_RUNTIME_CHECKS abstraction on
 Windows

Extend commit 2b2344b412 (MSVC: Add abstraction for runtime checks,
2025-01-22, v4.0.0-rc1~92^2) to cover LLVMFlang.  This is necessary
to configure with CMP0184's NEW behavior.
---
 Modules/Platform/Windows-LLVMFlang-Fortran.cmake | 5 +++++
 Tests/MSVCRuntimeChecks/override-common.cmake    | 6 ++++++
 Tests/MSVCRuntimeChecks/verify.h                 | 3 ++-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Modules/Platform/Windows-LLVMFlang-Fortran.cmake b/Modules/Platform/Windows-LLVMFlang-Fortran.cmake
index c2ccec6471..0f753dfd46 100644
--- a/Modules/Platform/Windows-LLVMFlang-Fortran.cmake
+++ b/Modules/Platform/Windows-LLVMFlang-Fortran.cmake
@@ -5,6 +5,11 @@ elseif("x${CMAKE_Fortran_SIMULATE_ID}" STREQUAL "xMSVC")
   include(Platform/Windows-MSVC)
   __windows_compiler_msvc(Fortran)
 
+  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_RUNTIME_CHECKS_PossibleDataLoss      "")
+  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_RUNTIME_CHECKS_StackFrameErrorCheck  "")
+  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_RUNTIME_CHECKS_UninitializedVariable "")
+  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_RUNTIME_CHECKS_RTCsu                 "")
+
   if(CMAKE_Fortran_COMPILER_VERSION VERSION_GREATER_EQUAL 18.0)
     set(_LLVMFlang_LINK_RUNTIME "")
     set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_RUNTIME_LIBRARY_MultiThreaded         "-fms-runtime-lib=static")
diff --git a/Tests/MSVCRuntimeChecks/override-common.cmake b/Tests/MSVCRuntimeChecks/override-common.cmake
index 024170232a..01d1322032 100644
--- a/Tests/MSVCRuntimeChecks/override-common.cmake
+++ b/Tests/MSVCRuntimeChecks/override-common.cmake
@@ -4,6 +4,12 @@ if("${CMAKE_${lang}_COMPILER_ID};${CMAKE_${lang}_SIMULATE_ID};${CMAKE_${lang}_CO
   set(empty_StackFrameErrorCheck 1)
   set(empty_UninitializedVariable 1)
   set(empty_RTCsu 1)
+elseif("${CMAKE_${lang}_COMPILER_ID};${CMAKE_${lang}_SIMULATE_ID};${lang}" STREQUAL "LLVMFlang;MSVC;Fortran")
+  # LLVMFlang does not actually support these, so Windows-LLVMFlang-Fortran passes no flags.
+  set(empty_PossibleDataLoss 1)
+  set(empty_StackFrameErrorCheck 1)
+  set(empty_UninitializedVariable 1)
+  set(empty_RTCsu 1)
 elseif("${CMAKE_${lang}_COMPILER_ID};${CMAKE_${lang}_SIMULATE_ID};${lang}" MATCHES "^Intel(LLVM)?;MSVC;Fortran$")
   # IntelLLVM Fortran does not actually support these, so Windows-IntelLLVM-Fortran passes no flags.
   set(empty_PossibleDataLoss 1)
diff --git a/Tests/MSVCRuntimeChecks/verify.h b/Tests/MSVCRuntimeChecks/verify.h
index aae595b98c..3d26926a7a 100644
--- a/Tests/MSVCRuntimeChecks/verify.h
+++ b/Tests/MSVCRuntimeChecks/verify.h
@@ -1,6 +1,7 @@
 /* Some compilers ignore the -RTC flags even if specified.  */
 #if (defined(_MSC_VER) && _MSC_VER <= 1310) || defined(__clang__) ||          \
-  defined(__INTEL_LLVM_COMPILER) || defined(__INTEL_COMPILER)
+  defined(__flang__) || defined(__INTEL_LLVM_COMPILER) ||                     \
+  defined(__INTEL_COMPILER)
 #  define NO__MSVC_RUNTIME_CHECKS
 #endif