From 1b680fe697d741dbd46eb59eee6f2f09e3dde040 Mon Sep 17 00:00:00 2001
From: Sascha Kratky <skratky@gmail.com>
Date: Sat, 22 Sep 2012 16:26:47 +0200
Subject: [PATCH] cotire 1.1.6

---
 CMake/cotire.cmake | 11 +++++++++--
 HISTORY.md         |  6 ++++++
 MANUAL.md          | 26 +++++++++++++++++++++++++-
 3 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/CMake/cotire.cmake b/CMake/cotire.cmake
index 2936fee..6260bbe 100644
--- a/CMake/cotire.cmake
+++ b/CMake/cotire.cmake
@@ -44,7 +44,7 @@ if (NOT CMAKE_SCRIPT_MODE_FILE)
 endif()
 
 set (COTIRE_CMAKE_MODULE_FILE "${CMAKE_CURRENT_LIST_FILE}")
-set (COTIRE_CMAKE_MODULE_VERSION "1.1.5")
+set (COTIRE_CMAKE_MODULE_VERSION "1.1.6")
 
 include(CMakeParseArguments)
 
@@ -943,7 +943,11 @@ function (cotire_scan_includes _includesVar)
 		# cl.exe messes with the output streams unless the environment variable VS_UNICODE_OUTPUT is cleared
 		unset (ENV{VS_UNICODE_OUTPUT})
 	endif()
-	execute_process(COMMAND ${_cmd} WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}" OUTPUT_QUIET ERROR_VARIABLE _output)
+	execute_process(COMMAND ${_cmd} WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+		RESULT_VARIABLE _result OUTPUT_QUIET ERROR_VARIABLE _output)
+	if (_result)
+		message (STATUS "Result ${_result} scanning includes of ${_existingSourceFiles}.")
+	endif()
 	cotire_parse_includes(
 		"${_option_LANGUAGE}" "${_output}"
 		"${_option_IGNORE_PATH}" "${_option_INCLUDE_PATH}"
@@ -2030,6 +2034,9 @@ function (cotire_setup_pch_target _languages _configurations _target)
 			cotire_init_target("${_pchTargetName}")
 			cotire_add_to_pch_all_target(${_pchTargetName})
 		endif()
+	else()
+		# for other generators, we add the "clean all" target to clean up the precompiled header
+		cotire_setup_clean_all_target()
 	endif()
 endfunction()
 
diff --git a/HISTORY.md b/HISTORY.md
index bf78bd4..c2e9dda 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -1,3 +1,9 @@
+## 1.1.6 (2012-09-22)
+
+* check result code upon scanning includes.
+* always add a `clean_cotire` target to easily clean up cotire generated files.
+* add section on `extern "C"` linkage issues to manual.
+
 ## 1.1.5 (2012-08-17)
 
  * new cache variable `COTIRE_UNITY_SOURCE_EXCLUDE_EXTENSIONS` can be set to globally exclude
diff --git a/MANUAL.md b/MANUAL.md
index 2620a18..ed2ad35 100644
--- a/MANUAL.md
+++ b/MANUAL.md
@@ -296,7 +296,7 @@ ignore other project related headers in `CMAKE_SOURCE_DIR`:
 The properties `COTIRE_PREFIX_HEADER_IGNORE_PATH` and `COTIRE_PREFIX_HEADER_INCLUDE_PATH` can
 also be set on directories.
 
-The following cache variables also affect the selection of prefix headers.
+The following cache variables also affect the selection of prefix headers:
 
 * Directory paths in `COTIRE_ADDITIONAL_PREFIX_HEADER_IGNORE_PATH` will be added to the list of
 ignored directories when the prefix header file is created.
@@ -312,6 +312,30 @@ precompiled header and would result in a rebuild of the whole target. To make th
 creation dependent on changes to certain target source files, the source file property
 `COTIRE_DEPENDENCY` can be set to `TRUE` for those files.
 
+### fixing linkage issues
+
+When a C++ program uses `extern "C"` on a system header file, cotire will not be able to detect
+that the include file needs C linkage and will include the file with C++ linkage in the generated
+prefix header instead. For example, the C interface to BLAS `cblas.h` usually has to be included
+as `extern "C"` in a C++ program:
+
+    extern "C" {
+    #include <cblas.h>
+    }
+
+The presence of `extern "C"` includes will prevent cotired targets from being linked successfully
+because of unresolved function references using the wrong linkage. To work around the problem,
+the property `COTIRE_PREFIX_HEADER_IGNORE_PATH` can be set to a list including the full path of
+the `extern "C"` header file. Here's an example:
+
+    set_property(DIRECTORY
+        PROPERTY COTIRE_PREFIX_HEADER_IGNORE_PATH
+            "${ATLAS_INCLUDE_DIR}/cblas.h"
+            "${CMAKE_SOURCE_DIR}" "${CMAKE_BINARY_DIR}")
+
+That way `cblas.h` will not be included in the generated prefix header and will not cause problems
+upon linking.
+
 ### configuring the generation of the unity source
 
 By default cotire adds all target source file to the generated unity source. In most cases a