Move 'no runtime' warning to flang

Author: Meinersbur

flang/CMakeLists.txt

@@ -242,8 +242,10 @@ else()
   include_directories(SYSTEM ${MLIR_TABLEGEN_OUTPUT_DIR})
 endif()
 
-if (NOT "flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
-  message(STATUS "Not building Flang-RT. For a usable Fortran toolchain, either add LLVM_ENABLE_RUNTIMES=flang-rt, or compile a standalone Flang-RT.")
+if (FLANG_STANDALONE_BUILD)
+  message(STATUS "Not building Flang-RT. For a usable Fortran toolchain, compile a standalone Flang-RT.")
+elseif (NOT "flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
+  message(STATUS "Not building Flang-RT. For a usable Fortran toolchain, either set FLANG_ENABLE_FLANG_RT=ON, add LLVM_ENABLE_RUNTIMES=flang-rt, or compile a standalone Flang-RT.")
 endif ()
 
 set(FLANG_TOOLS_INSTALL_DIR "${CMAKE_INSTALL_BINDIR}" CACHE PATH

llvm/CMakeLists.txt

@@ -187,16 +187,13 @@ foreach(proj IN LISTS LLVM_ENABLE_RUNTIMES)
   endif()
 endforeach()
 
-option(FLANG_ENABLE_FLANG_RT "Implicitly add LLVM_ENABLE_RUNTIMES=flang-rt when compiling Flang" ON)
 if ("flang" IN_LIST LLVM_ENABLE_PROJECTS)
+  option(FLANG_ENABLE_FLANG_RT "Implicitly add LLVM_ENABLE_RUNTIMES=flang-rt when compiling Flang" ON)
   if (NOT "flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
-    message(STATUS "Enabling Flang-RT as a dependency of Flang"
-      "Flang-RT is required for a fully working Flang toolchain."
-      "If you intend to compile Flang-RT separately following the instructions at"
-      "https://github.com/llvm/llvm-project/blob/main/flang-rt/README.md#standalone-runtimes-build"
-      "you should use -DFLANG_ENABLE_FLANG_RT=OFF to not build Flang-RT as part of this build."
-    )
-    list(APPEND LLVM_ENABLE_RUNTIMES "flang-rt")
+    if (FLANG_ENABLE_FLANG_RT)
+      message(STATUS "Enabling Flang-RT as a dependency of Flang")
+      list(APPEND LLVM_ENABLE_RUNTIMES "flang-rt")
+    endf ()
   endif()
 endif ()