diff --git a/src/3rdParty/salomesmesh/src/MEFISTO2/trte.c b/src/3rdParty/salomesmesh/src/MEFISTO2/trte.c
index 4edfb65e9..3aec27788 100644
--- a/src/3rdParty/salomesmesh/src/MEFISTO2/trte.c
+++ b/src/3rdParty/salomesmesh/src/MEFISTO2/trte.c
@@ -819,9 +819,9 @@ integer nosui3_(integer *i__)
 /*        alors il y a une erreur */
 	if (nosoar[*noar * nosoar_dim1 + 4] > 0 && nosoar[*noar * nosoar_dim1 
 		+ 5] > 0) {
-	    if (nosoar[*noar * nosoar_dim1 + 4] != *nt1 && nosoar[*noar * 
-		    nosoar_dim1 + 4] != *nt2 || nosoar[*noar * nosoar_dim1 + 
-		    5] != *nt1 && nosoar[*noar * nosoar_dim1 + 5] != *nt2) {
+	    if ((nosoar[*noar * nosoar_dim1 + 4] != *nt1 && nosoar[*noar * 
+		    nosoar_dim1 + 4] != *nt2) || (nosoar[*noar * nosoar_dim1 + 
+		    5] != *nt1 && nosoar[*noar * nosoar_dim1 + 5] != *nt2)) {
 /*                arete appartenant a plus de 2 triangles => erreur */
 		if (*ierr >= 0) {
 		 //   io___14.ciunit = unites_1.imprim;
@@ -2300,8 +2300,8 @@ L15:
 	    dmin__ = pxyd[*ns1 * 3 + 1];
 	    dmax__ = pxyd[*ns2 * 3 + 1];
 	}
-	if (xrmin <= dmin__ && dmin__ <= xrmax || xrmin <= dmax__ && dmax__ <=
-		 xrmax) {
+	if ((xrmin <= dmin__ && dmin__ <= xrmax) || (xrmin <= dmax__ && dmax__ <=
+		 xrmax)) {
 	    if (pxyd[*ns1 * 3 + 2] > pxyd[*ns3 * 3 + 2]) {
 		dmin__ = pxyd[*ns3 * 3 + 2];
 		dmax__ = pxyd[*ns1 * 3 + 2];
@@ -2309,8 +2309,8 @@ L15:
 		dmin__ = pxyd[*ns1 * 3 + 2];
 		dmax__ = pxyd[*ns3 * 3 + 2];
 	    }
-	    if (yrmin <= dmin__ && dmin__ <= yrmax || yrmin <= dmax__ && 
-		    dmax__ <= yrmax) {
+	    if ((yrmin <= dmin__ && dmin__ <= yrmax) || (yrmin <= dmax__ && 
+		    dmax__ <= yrmax)) {
 
 /*              nte est un te feuille et interne au rectangle englobant */
 /*              ======================================================= */
@@ -2688,8 +2688,8 @@ L10:
 	    dmin__ = pxyd[ns1 * 3 + 1];
 	    dmax__ = pxyd[ns2 * 3 + 1];
 	}
-	if (xrmin <= dmin__ && dmin__ <= xrmax || xrmin <= dmax__ && dmax__ <=
-		 xrmax) {
+	if ((xrmin <= dmin__ && dmin__ <= xrmax) || (xrmin <= dmax__ && dmax__ <=
+		 xrmax)) {
 	    if (pxyd[ns1 * 3 + 2] > pxyd[ns3 * 3 + 2]) {
 		dmin__ = pxyd[ns3 * 3 + 2];
 		dmax__ = pxyd[ns1 * 3 + 2];
@@ -2697,8 +2697,8 @@ L10:
 		dmin__ = pxyd[ns1 * 3 + 2];
 		dmax__ = pxyd[ns3 * 3 + 2];
 	    }
-	    if (yrmin <= dmin__ && dmin__ <= yrmax || yrmin <= dmax__ && 
-		    dmax__ <= yrmax) {
+	    if ((yrmin <= dmin__ && dmin__ <= yrmax) || (yrmin <= dmax__ && 
+		    dmax__ <= yrmax)) {
 
 /*              te minimal et interne au rectangle englobant */
 /*              -------------------------------------------- */
@@ -9057,9 +9057,9 @@ L150:
 		    if (nosoar[i__ * nosoar_dim1 + 1] > 0 && nosoar[i__ * 
 			    nosoar_dim1 + 4] > 0) {
 /*                    arete non vide */
-			if (nosoar[i__ * nosoar_dim1 + 2] == ns[k - 1] || 
-				nosoar[i__ * nosoar_dim1 + 1] == ns[k - 1] && 
-				nosoar[i__ * nosoar_dim1 + 2] > 0) {
+			if  (nosoar[i__ * nosoar_dim1 + 2] == ns[k - 1] || 
+				(nosoar[i__ * nosoar_dim1 + 1] == ns[k - 1] && 
+				 nosoar[i__ * nosoar_dim1 + 2] > 0)) {
 /*                       arete active de sommet ns(k) */
 			    noarst[ns[k - 1]] = i__;
 			    goto L8;
diff --git a/src/App/Expression.cpp b/src/App/Expression.cpp
index 4fba24580..486100f45 100644
--- a/src/App/Expression.cpp
+++ b/src/App/Expression.cpp
@@ -1751,7 +1751,15 @@ int ExpressionParserlex(void);
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
 // Scanner, defined in ExpressionParser.l
+#if defined(__clang__)
+# pragma clang diagnostic push
+# pragma clang diagnostic ignored "-Wsign-compare"
+# pragma clang diagnostic ignored "-Wunneeded-internal-declaration"
+#endif
 #include "lex.ExpressionParser.c"
+#if defined(__clang__)
+# pragma clang diagnostic pop
+#endif
 #endif // DOXYGEN_SHOULD_SKIP_THIS
 #ifdef _MSC_VER
 # define strdup _strdup
diff --git a/src/Base/Quantity.cpp b/src/Base/Quantity.cpp
index 9c75f6762..bdbcfe7ae 100644
--- a/src/Base/Quantity.cpp
+++ b/src/Base/Quantity.cpp
@@ -356,7 +356,15 @@ int QuantityLexer(void);
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
 // Scanner, defined in QuantityParser.l
+#if defined(__clang__)
+# pragma clang diagnostic push
+# pragma clang diagnostic ignored "-Wsign-compare"
+# pragma clang diagnostic ignored "-Wunneeded-internal-declaration"
+#endif
 #include "QuantityLexer.c"
+#if defined(__clang__)
+# pragma clang diagnostic pop
+#endif
 #endif // DOXYGEN_SHOULD_SKIP_THIS
 }
 
diff --git a/src/Gui/SelectionFilter.cpp b/src/Gui/SelectionFilter.cpp
index ed68c193a..6ea185df2 100644
--- a/src/Gui/SelectionFilter.cpp
+++ b/src/Gui/SelectionFilter.cpp
@@ -347,7 +347,15 @@ int SelectionFilterlex(void);
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
 // Scanner, defined in SelectionFilter.l
+#if defined(__clang__)
+# pragma clang diagnostic push
+# pragma clang diagnostic ignored "-Wsign-compare"
+# pragma clang diagnostic ignored "-Wunneeded-internal-declaration"
+#endif
 #include "lex.SelectionFilter.c"
+#if defined(__clang__)
+# pragma clang diagnostic pop
+#endif
 #endif // DOXYGEN_SHOULD_SKIP_THIS
 }
 
diff --git a/src/Gui/WidgetFactory.cpp b/src/Gui/WidgetFactory.cpp
index 295c5118a..c6cdeb0a0 100644
--- a/src/Gui/WidgetFactory.cpp
+++ b/src/Gui/WidgetFactory.cpp
@@ -40,7 +40,11 @@
 #endif
 #endif
 
-#ifdef __GNUC__
+// class and struct used for SbkObject
+#if defined(__clang__)
+# pragma clang diagnostic push
+# pragma clang diagnostic ignored "-Wmismatched-tags"
+#elif defined (__GNUC__)
 # pragma GCC diagnostic push
 # pragma GCC diagnostic ignored "-Wunused-parameter"
 #endif
@@ -81,7 +85,9 @@ PyTypeObject** SbkPySide2_QtWidgetsTypes=NULL;
 # endif
 #endif
 
-#ifdef __GNUC__
+#if defined(__clang__)
+# pragma clang diagnostic pop
+#elif defined (__GNUC__)
 # pragma GCC diagnostic pop
 #endif