From ef49ed0fe1034b1452bea4965f637671e68c008d Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Mon, 4 Dec 2023 20:04:03 -0500
Subject: LLVMFlang: Fix MSVC ABI debug information format options

In commit 26bf32cdc6 (LLVMFlang: Add support for targeting MSVC ABI on
Windows, 2023-09-28, v3.28.0-rc1~10^2) we incorrectly recorded `-g` as
supporting the `ProgramDatabase` format, but it is actually `Embedded`,
matching Clang.

In order to support easy integration with C and C++ projects that use
the `.pdb` debug formats, pretend LLVMFlang supports them and just don't
actually emit any debug information.

Issue: #24840
---
 Modules/Platform/Windows-LLVMFlang-Fortran.cmake        | 12 +++++++-----
 Tests/CMakeLists.txt                                    |  5 +----
 Tests/MSVCDebugInformationFormat/override-Fortran.cmake |  8 ++++++++
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/Modules/Platform/Windows-LLVMFlang-Fortran.cmake b/Modules/Platform/Windows-LLVMFlang-Fortran.cmake
index 3e22a6e..57e36c6 100644
--- a/Modules/Platform/Windows-LLVMFlang-Fortran.cmake
+++ b/Modules/Platform/Windows-LLVMFlang-Fortran.cmake
@@ -17,11 +17,13 @@ elseif("x${CMAKE_Fortran_SIMULATE_ID}" STREQUAL "xMSVC")
   set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_RUNTIME_LIBRARY_MultiThreadedDebug    "")
   set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_RUNTIME_LIBRARY_MultiThreadedDebugDLL "")
 
-  # FIXME(LLVMFlang): It does not provide all debug information format flags or predefines.
-  # It should be given a flag to enable Embedded debug information like MSVC -Z7.
-  #set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_Embedded)        # not supported by LLVMFlang
-  #set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_EditAndContinue) # not supported by LLVMFlang
-  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_ProgramDatabase "-g")
+  # LLVMFlang, like Clang, does not provide all debug information format flags.
+  # In order to provide easy integration with C and C++ projects that use the
+  # other debug information formats, pretend to support them, and just do not
+  # actually generate any debug information for Fortran.
+  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_Embedded        -g)
+  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_ProgramDatabase "") # not supported by LLVMFlang
+  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_EditAndContinue "") # not supported by LLVMFlang
 
   set(CMAKE_Fortran_COMPILE_OBJECT "<CMAKE_Fortran_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -o <OBJECT> -c <SOURCE>")
 
diff --git a/Tests/CMakeLists.txt b/Tests/CMakeLists.txt
index 4c61eab..a1619ec 100644
--- a/Tests/CMakeLists.txt
+++ b/Tests/CMakeLists.txt
@@ -2154,10 +2154,7 @@ if(BUILD_TESTING)
     endif()
 
     set(MSVCDebugInformationFormat_BUILD_OPTIONS -DCMake_TEST_CUDA=${CMake_TEST_CUDA})
-    if(CMAKE_Fortran_COMPILER
-        # FIXME(LLVMFlang): It does not provide debug information format flags or predefines.
-        AND NOT CMAKE_Fortran_COMPILER_ID STREQUAL "LLVMFlang"
-        )
+    if(CMAKE_Fortran_COMPILER)
       list(APPEND MSVCDebugInformationFormat_BUILD_OPTIONS -DCMake_TEST_Fortran=1)
     endif()
     ADD_TEST_MACRO(MSVCDebugInformationFormat)
diff --git a/Tests/MSVCDebugInformationFormat/override-Fortran.cmake b/Tests/MSVCDebugInformationFormat/override-Fortran.cmake
index 5d2db58..8bc2067 100644
--- a/Tests/MSVCDebugInformationFormat/override-Fortran.cmake
+++ b/Tests/MSVCDebugInformationFormat/override-Fortran.cmake
@@ -2,3 +2,11 @@ set(var "CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_Embedded")
 string(REPLACE "-Z7" "-Z7;-DTEST_Z7" "${var}" "${${var}}")
 set(var "CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_ProgramDatabase")
 string(REPLACE "-Zi" "-Zi;-DTEST_Zi" "${var}" "${${var}}")
+
+if(CMAKE_Fortran_COMPILER_ID STREQUAL "LLVMFlang")
+  set(var "CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_Embedded")
+  string(REPLACE "-g" "-g;-DTEST_Z7" "${var}" "${${var}}")
+  # LLVMFlang does not actually support these, but Windows-LLVMFlang-Fortran pretends it does.
+  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_ProgramDatabase "-DTEST_Zi")
+  set(CMAKE_Fortran_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_EditAndContinue "-DTEST_ZI")
+endif()
-- 
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