From 5f05a3c25e1480648f46c9ccbf775225f9e8e32d Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Fri, 17 Sep 2010 09:25:36 -0400
Subject: MinGW: Support long object file lists

Use a combination of response files and the archiver to support long
object file lists that do not fit in the Windows command-line length
limit.  This can work only with GCC >= 4 because the MinGW GCC 3.x
front-ends do not support response-file syntax.
---
 Modules/Platform/Windows-GNU-Fortran.cmake |  1 -
 Modules/Platform/Windows-GNU.cmake         | 35 +++++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/Modules/Platform/Windows-GNU-Fortran.cmake b/Modules/Platform/Windows-GNU-Fortran.cmake
index 8273a19..c66feed 100644
--- a/Modules/Platform/Windows-GNU-Fortran.cmake
+++ b/Modules/Platform/Windows-GNU-Fortran.cmake
@@ -1,3 +1,2 @@
 include(Platform/Windows-GNU)
 __windows_compiler_gnu(Fortran)
-set(CMAKE_Fortran_USE_RESPONSE_FILE_FOR_OBJECTS 0)
diff --git a/Modules/Platform/Windows-GNU.cmake b/Modules/Platform/Windows-GNU.cmake
index 79b2f80..ac635a5 100644
--- a/Modules/Platform/Windows-GNU.cmake
+++ b/Modules/Platform/Windows-GNU.cmake
@@ -76,7 +76,23 @@ macro(__windows_compiler_gnu lang)
 
   set(CMAKE_SHARED_LIBRARY_${lang}_FLAGS "") # No -fPIC on Windows
   set(CMAKE_${lang}_USE_RESPONSE_FILE_FOR_OBJECTS ${__WINDOWS_GNU_LD_RESPONSE})
-  set(CMAKE_${lang}_RESPONSE_FILE_LINK_FLAG "-Wl,@")
+
+  # We prefer "@" for response files but it is not supported by gcc 3.
+  execute_process(COMMAND ${CMAKE_${lang}_COMPILER} --version OUTPUT_VARIABLE _ver ERROR_VARIABLE _ver)
+  if("${_ver}" MATCHES "\\(GCC\\) 3\\.")
+    if("${lang}" STREQUAL "Fortran")
+      # The GNU Fortran compiler reports an error:
+      #   no input files; unwilling to write output files
+      # when the response file is passed with "-Wl,@".
+      set(CMAKE_Fortran_USE_RESPONSE_FILE_FOR_OBJECTS 0)
+    else()
+      # Use "-Wl,@" to pass the response file to the linker.
+      set(CMAKE_${lang}_RESPONSE_FILE_LINK_FLAG "-Wl,@")
+    endif()
+  elseif(CMAKE_${lang}_USE_RESPONSE_FILE_FOR_OBJECTS)
+    # Use "@" to pass the response file to the front-end.
+    set(CMAKE_${lang}_RESPONSE_FILE_LINK_FLAG "@")
+  endif()
 
   # Binary link rules.
   set(CMAKE_${lang}_CREATE_SHARED_MODULE
@@ -85,4 +101,21 @@ macro(__windows_compiler_gnu lang)
     "<CMAKE_${lang}_COMPILER> <CMAKE_SHARED_LIBRARY_${lang}_FLAGS> <LINK_FLAGS> <CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS> -o <TARGET> -Wl,--out-implib,<TARGET_IMPLIB> ${CMAKE_GNULD_IMAGE_VERSION} <OBJECTS> <LINK_LIBRARIES>")
   set(CMAKE_${lang}_LINK_EXECUTABLE
     "<CMAKE_${lang}_COMPILER> <FLAGS> <CMAKE_${lang}_LINK_FLAGS> <LINK_FLAGS> <OBJECTS>  -o <TARGET> -Wl,--out-implib,<TARGET_IMPLIB> ${CMAKE_GNULD_IMAGE_VERSION} <LINK_LIBRARIES>")
+
+  # Support very long lists of object files.
+  if("${CMAKE_${lang}_RESPONSE_FILE_LINK_FLAG}" STREQUAL "@")
+    foreach(rule CREATE_SHARED_MODULE CREATE_SHARED_LIBRARY LINK_EXECUTABLE)
+      # The gcc/collect2/ld toolchain does not use response files
+      # internally so we cannot pass long object lists.  Instead pass
+      # the object file list in a response file to the archiver to put
+      # them in a temporary archive.  Hand the archive to the linker.
+      string(REPLACE "<OBJECTS>" "-Wl,--whole-archive <OBJECT_DIR>/objects.a -Wl,--no-whole-archive"
+        CMAKE_${lang}_${rule} "${CMAKE_${lang}_${rule}}")
+      set(CMAKE_${lang}_${rule}
+        "<CMAKE_COMMAND> -E remove -f <OBJECT_DIR>/objects.a"
+        "<CMAKE_AR> cr <OBJECT_DIR>/objects.a <OBJECTS>"
+        "${CMAKE_${lang}_${rule}}"
+        )
+    endforeach()
+  endif()
 endmacro()
-- 
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