diff --git a/src/debug.c b/src/debug.c
index e42daf3..5d990d5 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -1,4 +1,5 @@
-/* Functions for printing debugging information when compiling with option -DDEBUGFULL
+/* Functions for printing debugging information when compiling with option -DDEBUGFULL.
+ * Should only be used with this macro, but IDE syntax checking works fine even without it.
  *
  * Copyright (C) ADDA contributors
  * This file is part of ADDA.
@@ -12,14 +13,6 @@
  * You should have received a copy of the GNU General Public License along with ADDA. If not, see
  * <http://www.gnu.org/licenses/>.
  */
-
-/* This file should be compiled only in full debug mode, hence the following declaration is redundant. However, it helps
- * proper syntax checking in IDE, such as Eclipse.
- */
-#ifndef DEBUGFULL
-#  define DEBUGFULL
-#endif
-
 #include "const.h" // keep this first
 #include "debug.h" // corresponding header
 // project headers
diff --git a/src/fft.c b/src/fft.c
index ed8b613..a9a0643 100644
--- a/src/fft.c
+++ b/src/fft.c
@@ -13,6 +13,14 @@
  * You should have received a copy of the GNU General Public License along with ADDA. If not, see
  * <http://www.gnu.org/licenses/>.
  */
+/* The following tests for compilation inconsistencies, but also helps proper syntax checking in IDE, such as Eclipse.
+ * Otherwise, a lot of unresolved-symbol errors are produced, when another build configuration is selected.
+ */
+#ifdef SPARSE
+#  error "This file is incompatible with SPARSE"
+#  undef SPARSE
+#endif
+
 #include "const.h" // keep this first
 #include "fft.h" // corresponding header
 // project headers
diff --git a/src/matvec.c b/src/matvec.c
index 83e9eac..6e1dcef 100644
--- a/src/matvec.c
+++ b/src/matvec.c
@@ -1,5 +1,6 @@
 /* Calculate local matrix vector product of decomposed interaction matrix with r_k or p_k, using a FFT-based convolution
  * algorithm. Also contains code for SPARSE (non-FFT) mode.
+ * Should not be used with OPENCL mode, but IDE syntax checking works fine even in this mode.
  *
  * Copyright (C) ADDA contributors
  * This file is part of ADDA.
@@ -36,9 +37,8 @@ extern doublecomplex * restrict arg_full;
 // defined and initialized in fft.c
 extern const doublecomplex * restrict Dmatrix,* restrict Rmatrix;
 extern doublecomplex * restrict Xmatrix,* restrict slices,* restrict slices_tr,* restrict slicesR,* restrict slicesR_tr;
-extern const size_t DsizeY,DsizeZ;
+extern const size_t DsizeY,DsizeZ,RsizeY;
 #endif // !SPARSE
-extern const size_t RsizeY;
 // defined and initialized in timing.c
 extern size_t TotalMatVec;
 
diff --git a/src/oclcore.c b/src/oclcore.c
index db8db53..4ce44d4 100644
--- a/src/oclcore.c
+++ b/src/oclcore.c
@@ -12,11 +12,11 @@
  * You should have received a copy of the GNU General Public License along with ADDA. If not, see
  * <http://www.gnu.org/licenses/>.
  */
-
-/* This file should be compiled only in OpenCL mode, hence the following declaration is redundant. However, it helps
- * proper syntax checking in IDE, such as Eclipse.
+/* The following tests for compilation inconsistencies, but also helps proper syntax checking in IDE, such as Eclipse.
+ * Otherwise, a lot of unresolved-symbol errors are produced, when another build configuration is selected.
  */
 #ifndef OPENCL
+#  error "This file requires OPENCL to be defined"
 #  define OPENCL
 #endif
 
diff --git a/src/oclmatvec.c b/src/oclmatvec.c
index 12e1aa5..cf18e6c 100644
--- a/src/oclmatvec.c
+++ b/src/oclmatvec.c
@@ -13,6 +13,18 @@
  * You should have received a copy of the GNU General Public License along with ADDA. If not, see
  * <http://www.gnu.org/licenses/>.
  */
+/* The following tests for compilation inconsistencies, but also helps proper syntax checking in IDE, such as Eclipse.
+ * Otherwise, a lot of unresolved-symbol errors are produced, when another build configuration is selected.
+ */
+#ifndef OPENCL
+#  error "This file requires OPENCL to be defined"
+#  define OPENCL
+#endif
+#ifdef SPARSE
+#  error "This file is incompatible with SPARSE"
+#  undef SPARSE
+#endif
+
 #include "const.h" // keep this first
 // project headers
 #include "comm.h"
diff --git a/src/prec_time.c b/src/prec_time.c
index 008538c..439ecc2 100644
--- a/src/prec_time.c
+++ b/src/prec_time.c
@@ -12,11 +12,11 @@
  * You should have received a copy of the GNU General Public License along with ADDA. If not, see
  * <http://www.gnu.org/licenses/>.
  */
-
-/* This file should be compiled only in precise timing mode, hence the following declaration is redundant. However, it
- * helps proper syntax checking in IDE, such as Eclipse.
+/* The following tests for compilation inconsistencies, but also helps proper syntax checking in IDE, such as Eclipse.
+ * Otherwise, a lot of unresolved-symbol errors are produced, when another build configuration is selected.
  */
 #ifndef PRECISE_TIMING
+#  error "This file requires PRECISE_TIMING to be defined"
 #  define PRECISE_TIMING
 #endif