From 99abe68ee8d51feb07ec3f50a5026494e33c7992 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Markus=20M=C3=BCtzel?= <markus.muetzel@gmx.de>
Date: Sat, 13 Jul 2024 23:25:38 +0200
Subject: [PATCH] Avoid compiler warnings about implicit function declarations.

Include header that declares functions from the UMFPACK library before
using them. Add path to that header to the preprocessor flags.
Also keep similar order of linker flags independent of whether the
bundled or an external UMFPACK library is used.

This warning is elevated to an error in LLVM Clang 18 (with default
compiler flags).
---
 fem/src/CMakeLists.txt    | 13 +++++++------
 fem/src/umf4_f77wrapper.c |  2 ++
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/fem/src/CMakeLists.txt b/fem/src/CMakeLists.txt
index d4335936eb..06eb07a3d9 100644
--- a/fem/src/CMakeLists.txt
+++ b/fem/src/CMakeLists.txt
@@ -179,18 +179,19 @@ ENDIF()
 # ElmerSolver libraries
 IF(UMFPACK_FOUND)
   SET(ELMERSOLVER_LIBRARIES matc fhuti binio arpack
+                          ${UMFPACK_LIBRARIES}
                           ${LAPACK_LIBRARIES} ${BLAS_LIBRARIES}
-			  ${UMFPACK_LIBRARIES}
                           ${CMAKE_DL_LIBS})
-			
-  INCLUDE_DIRECTORIES(${UMFPACK_INCLUDE_DIR})
+
+  TARGET_INCLUDE_DIRECTORIES(elmersolver PRIVATE ${UMFPACK_INCLUDE_DIR})
   #LIST(APPEND ELMERSOLVER_LIBRARIES ${UMFPACK_LIBRARIES})
   #TARGET_LINK_LIBRARIES(elmersolver "${UMFPACK_LIBRARIES}")
 ELSE()
-  SET(ELMERSOLVER_LIBRARIES matc umfpack 
-                          amd fhuti binio arpack
-                          ${LAPACK_LIBRARIES} ${BLAS_LIBRARIES} 
+  SET(ELMERSOLVER_LIBRARIES matc fhuti binio arpack
+                          umfpack amd
+                          ${LAPACK_LIBRARIES} ${BLAS_LIBRARIES}
                           ${CMAKE_DL_LIBS})
+  TARGET_INCLUDE_DIRECTORIES(elmersolver PRIVATE ${PROJECT_SOURCE_DIR}/umfpack/src/umfpack/include)
 ENDIF()
 
 IF(WITH_LUA)
diff --git a/fem/src/umf4_f77wrapper.c b/fem/src/umf4_f77wrapper.c
index 8b7d3d471d..683cd1a9aa 100644
--- a/fem/src/umf4_f77wrapper.c
+++ b/fem/src/umf4_f77wrapper.c
@@ -80,6 +80,8 @@
 
 #include "../config.h"
 
+#include "umfpack.h"
+
 #ifdef NULL
 #undef NULL
 #endif