cblas: mark cblas_xerbla and F77_xerbla symbols as weak

Author: veprbl

CBLAS/CMakeLists.txt

@@ -18,6 +18,10 @@ if(NOT FortranCInterface_GLOBAL_FOUND OR NOT FortranCInterface_MODULE_FOUND)
                  ${LAPACK_BINARY_DIR}/include/cblas_mangling.h)
 endif()
 
+include(CheckCSourceCompiles)
+check_c_source_compiles("void __attribute__((weak)) main() {};"
+                        HAS_ATTRIBUTE_WEAK_SUPPORT)
+
 include_directories(include ${LAPACK_BINARY_DIR}/include)
 add_subdirectory(include)
 add_subdirectory(src)

CBLAS/src/CMakeLists.txt

@@ -120,6 +120,9 @@ set_target_properties(
   VERSION ${LAPACK_VERSION}
   SOVERSION ${LAPACK_MAJOR_VERSION}
   )
+if(HAS_ATTRIBUTE_WEAK_SUPPORT)
+  target_compile_definitions(${CBLASLIB} PRIVATE HAS_ATTRIBUTE_WEAK_SUPPORT)
+endif()
 target_include_directories(${CBLASLIB} PUBLIC
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../include>
   $<INSTALL_INTERFACE:include>

CBLAS/src/cblas_xerbla.c

@@ -5,7 +5,11 @@
 #include "cblas.h"
 #include "cblas_f77.h"
 
-void cblas_xerbla(CBLAS_INDEX info, const char *rout, const char *form, ...)
+void
+#ifdef HAS_ATTRIBUTE_WEAK_SUPPORT
+__attribute__((weak))
+#endif
+cblas_xerbla(CBLAS_INDEX info, const char *rout, const char *form, ...)
 {
    extern int RowMajorStrg;
    char empty[1] = "";

CBLAS/src/xerbla.c

@@ -6,10 +6,15 @@
 #define XerblaStrLen 6
 #define XerblaStrLen1 7
 
+void
+#ifdef HAS_ATTRIBUTE_WEAK_SUPPORT
+__attribute__((weak))
+#endif
+F77_xerbla
 #ifdef F77_CHAR
-void F77_xerbla(F77_CHAR F77_srname, void *vinfo)
+(F77_CHAR F77_srname, void *vinfo)
 #else
-void F77_xerbla(char *srname, void *vinfo)
+(char *srname, void *vinfo)
 #endif
 
 {