POSITION_INDEPENDENT_CODE: Manage link flags for executables

Fixes: #14983, #16561

1 files changed, 146 insertions, 0 deletions

diff --git a/Modules/Internal/CMakeCheckCompilerFlag.cmake b/Modules/Internal/CMakeCheckCompilerFlag.cmake
new file mode 100644
index 0000000..ca9b356
--- /dev/null
+++ b/Modules/Internal/CMakeCheckCompilerFlag.cmake
@@ -0,0 +1,146 @@
+# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+# file Copyright.txt or https://cmake.org/licensing for details.
+
+#[=[
+
+NOTE: This function is used internally by CMake. Projects should not include
+      this file directly.
+
+The cmake_check_compiler_flag() function can be used to compile and link a
+source file to check whether a specific compiler or linker flag is supported.
+The function does not use the try_compile() command so as to avoid infinite
+recursion.  It may not work for all platforms or toolchains, the caller is
+responsible for ensuring it is only called in valid situations.
+
+Parameters:
+  lang   - Language to check.
+  flag   - The flag to add to the compile/link command line.
+  result - Boolean output variable.  It will be stored in the cache as an
+           internal variable and if true, will cause future tests that assign
+           to that variable to be bypassed.
+
+Optional parameters:
+  SRC_EXT         - Overrides the extension of the source file used for the
+                    check.  Defaults are 'c' (C), 'cxx' (CXX), 'F' (Fortran).
+  COMMAND_PATTERN - Pattern to be used for the command line. The default is
+                    '<FLAG> -o <OUTPUT> <SOURCE>'
+  FAIL_REGEX      - List of additional regular expressions that, if matched by
+                    the output, give a failed result for the check.  A common
+                    set of regular expressions will be included in addition to
+                    those given by FAIL_REGEX.
+
+#]=]
+
+include_guard(GLOBAL)
+include(CMakeCheckCompilerFlagCommonPatterns)
+
+function(CMAKE_CHECK_COMPILER_FLAG lang flag result)
+  # Cache results between runs similar to check_<lang>_source_compiles()
+  if(DEFINED ${result})
+    return()
+  endif()
+
+  set(comment "Is the '${flag}' option(s) supported")
+  string(REPLACE ";" " " comment "${comment}")
+
+  if (NOT lang MATCHES "^(C|CXX|Fortran|ASM)$")
+    # other possible languages are not supported
+    # log message to keep trace of this problem...
+    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+      "Function 'CMAKE_CHECK_COMPILER_FLAG' called with unsupported language: ${lang}\n")
+    set(${result} FALSE CACHE INTERNAL ${comment})
+    return()
+  endif()
+  if (lang STREQUAL "ASM")
+    # assume ASM compiler is a multi-language compiler, so supports C language as well
+    set(check_lang C)
+  else()
+    set(check_lang ${lang})
+  endif()
+
+  cmake_parse_arguments(CCCF "" "SRC_EXT;COMMAND_PATTERN" "FAIL_REGEX" ${ARGN})
+
+  if (NOT CCCF_COMMAND_PATTERN)
+    set (CCCF_COMMAND_PATTERN "<FLAG> -o <OUTPUT> <SOURCE>")
+  endif()
+
+  list (APPEND CCCF_FAIL_REGEX "argument unused during compilation") # clang
+  if (check_lang STREQUAL "C")
+    list(APPEND CCCF_FAIL_REGEX
+      "command line option .* is valid for .* but not for C") # GNU
+  elseif(check_lang STREQUAL "CXX")
+    list(APPEND CCCF_FAIL_REGEX
+      "command line option .* is valid for .* but not for C\\+\\+") # GNU
+  elseif(check_lang STREQUAL "Fortran")
+    list(APPEND CCCF_FAIL_REGEX
+      "command line option .* is valid for .* but not for Fortran") # GNU
+  endif()
+
+  # Add patterns for common errors
+  check_compiler_flag_common_patterns(COMPILER_FLAG_COMMON_PATTERNS)
+  foreach(arg IN LISTS COMPILER_FLAG_COMMON_PATTERNS)
+    if(arg MATCHES "^FAIL_REGEX$")
+      continue()
+    endif()
+    list(APPEND CCCF_FAIL_REGEX "${arg}")
+  endforeach()
+
+  if(NOT CCCF_SRC_EXT)
+    if (check_lang STREQUAL "C")
+      set(CCCF_SRC_EXT c)
+    elseif(check_lang STREQUAL "CXX")
+      set(CCCF_SRC_EXT cxx)
+    elseif(check_lang STREQUAL "Fortran")
+      set(CCCF_SRC_EXT F)
+    endif()
+  endif()
+
+  # Compute the directory in which to run the test.
+  set(COMPILER_FLAG_DIR "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp")
+  # Compute source and output files.
+  set(COMPILER_FLAG_SRC
+    "${COMPILER_FLAG_DIR}/CompilerFlag${lang}.${CCCF_SRC_EXT}")
+  if(check_lang STREQUAL "Fortran")
+    file(WRITE "${COMPILER_FLAG_SRC}"
+      "      program simple\n      end program simple\n")
+  else()
+    file(WRITE "${COMPILER_FLAG_SRC}" "int main (void)\n{ return 0; }\n")
+  endif()
+  get_filename_component(COMPILER_FLAG_EXE "${COMPILER_FLAG_SRC}" NAME_WE)
+  string(APPEND COMPILER_FLAG_EXE "${CMAKE_EXECUTABLE_SUFFIX}")
+
+  # Build command line
+  separate_arguments(CCCF_COMMAND_PATTERN UNIX_COMMAND
+    "${CCCF_COMMAND_PATTERN}")
+  list(TRANSFORM CCCF_COMMAND_PATTERN REPLACE "<SOURCE>" "${COMPILER_FLAG_SRC}")
+  list(TRANSFORM CCCF_COMMAND_PATTERN REPLACE "<OUTPUT>" "${COMPILER_FLAG_EXE}")
+  list(TRANSFORM CCCF_COMMAND_PATTERN REPLACE "<FLAG>" "${flag}")
+
+  execute_process(
+    COMMAND "${CMAKE_COMMAND}" -E env LC_ALL=C LC_MESSAGES=C LANG=C
+            "${CMAKE_${lang}_COMPILER}" ${CCCF_COMMAND_PATTERN}
+    WORKING_DIRECTORY "${COMPILER_FLAG_DIR}"
+    OUTPUT_VARIABLE COMPILER_FLAG_OUTPUT
+    ERROR_VARIABLE COMPILER_FLAG_OUTPUT
+    RESULT_VARIABLE COMPILER_FLAG_RESULT)
+
+  # Record result in the cache so we can avoid re-testing every CMake run
+  if (COMPILER_FLAG_RESULT)
+    set(${result} FALSE CACHE INTERNAL ${comment})
+  else()
+    foreach(regex IN LISTS CCCF_FAIL_REGEX)
+      if(COMPILER_FLAG_OUTPUT MATCHES "${regex}")
+        set(${result} FALSE CACHE INTERNAL ${comment})
+      endif()
+    endforeach()
+  endif()
+  if (DEFINED ${result})
+    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+        "Determining if the ${flag} option "
+        "is supported for ${lang} language failed with the following output:\n"
+        "${COMPILER_FLAG_OUTPUT}\n")
+    return()
+  endif()
+
+  set(${result} TRUE CACHE INTERNAL ${comment})
+endfunction()