[compiler-rt] r339559 - [CMake] Fix bug in `add_weak_symbols()` function.

[Dan Liew via llvm-commits]

Author: delcypher
Date: Mon Aug 13 05:59:38 2018
New Revision: 339559

URL: http://llvm.org/viewvc/llvm-project?rev=339559&view=rev
Log:
[CMake] Fix bug in `add_weak_symbols()` function.

Previously the the `weak_symbols.txt` files could be modified and the
build system wouldn't update the link flags automatically. Instead the
developer had to know to reconfigure CMake manually.

This is now fixed by telling CMake that the file being used to
read weak symbols from is a configure-time dependency.

Differential Revision: https://reviews.llvm.org/D50059

Modified:
    compiler-rt/trunk/cmake/Modules/SanitizerUtils.cmake

Modified: compiler-rt/trunk/cmake/Modules/SanitizerUtils.cmake
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/cmake/Modules/SanitizerUtils.cmake?rev=339559&r1=339558&r2=339559&view=diff
==============================================================================
--- compiler-rt/trunk/cmake/Modules/SanitizerUtils.cmake (original)
+++ compiler-rt/trunk/cmake/Modules/SanitizerUtils.cmake Mon Aug 13 05:59:38 2018
@@ -51,7 +51,15 @@ endmacro()
 # This function is only used on Darwin, where undefined symbols must be specified
 # in the linker invocation.
 function(add_weak_symbols libname link_flags)
-  file(STRINGS "${COMPILER_RT_SOURCE_DIR}/lib/${libname}/weak_symbols.txt" WEAK_SYMBOLS)
+  set(weak_symbols_file "${COMPILER_RT_SOURCE_DIR}/lib/${libname}/weak_symbols.txt")
+  file(STRINGS  "${weak_symbols_file}" WEAK_SYMBOLS)
+  # Add this file as a configure-time dependency so that changes to this
+  # file trigger a re-configure. This is necessary so that `${link_flags}`
+  # is changed when appropriate.
+  set_property(
+    DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+    APPEND
+    PROPERTY CMAKE_CONFIGURE_DEPENDS "${weak_symbols_file}")
   set(local_link_flags ${${link_flags}})
   foreach(SYMBOL ${WEAK_SYMBOLS})
     set(local_link_flags ${local_link_flags} -Wl,-U,${SYMBOL})