diff --git a/scilab/modules/ast/includes/exps/opexp.hxx b/scilab/modules/ast/includes/exps/opexp.hxx
index ed425c5..43cf7f8 100644
--- a/scilab/modules/ast/includes/exps/opexp.hxx
+++ b/scilab/modules/ast/includes/exps/opexp.hxx
@@ -254,6 +254,7 @@ public:
             case unknown:
                 return L"unknown";
         }
+        return L"";
     }
 
 
diff --git a/scilab/modules/ast/src/cpp/analysis/ConstraintManager.cpp b/scilab/modules/ast/src/cpp/analysis/ConstraintManager.cpp
index 72cd0f4..3ef42ab 100644
--- a/scilab/modules/ast/src/cpp/analysis/ConstraintManager.cpp
+++ b/scilab/modules/ast/src/cpp/analysis/ConstraintManager.cpp
@@ -96,6 +96,7 @@ bool ConstraintManager::check(const MPolyConstraintSet & set, const std::vector<
             }
         }
     }
+    return false;
 }
 
 bool ConstraintManager::check(Kind kind, const std::vector<GVN::Value *> & values)
diff --git a/scilab/modules/ast/src/cpp/analysis/InferenceConstraints.cpp b/scilab/modules/ast/src/cpp/analysis/InferenceConstraints.cpp
index e0853cc..b5d5bfb 100644
--- a/scilab/modules/ast/src/cpp/analysis/InferenceConstraints.cpp
+++ b/scilab/modules/ast/src/cpp/analysis/InferenceConstraints.cpp
@@ -187,6 +187,7 @@ InferenceConstraint::Result MPolyConstraint::check(GVN & gvn, const std::vector<
             }
         }
     }
+    return Result::RESULT_DUNNO;
 }
 
 MPolyConstraintSet MPolyConstraint::getMPConstraints(const std::vector<GVN::Value *> & values) const