From da3583b1db45ede894b5c6345b3fb853b0bb6eac Mon Sep 17 00:00:00 2001
From: bubnikv <bubnikv@gmail.com>
Date: Thu, 27 Jun 2019 09:48:19 +0200
Subject: [PATCH] Fix of https://github.com/prusa3d/PrusaSlicer/issues/2516

---
 src/libslic3r/Config.cpp | 8 ++++----
 src/libslic3r/Config.hpp | 6 +++++-
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/libslic3r/Config.cpp b/src/libslic3r/Config.cpp
index 0738b77c6..76329ccee 100644
--- a/src/libslic3r/Config.cpp
+++ b/src/libslic3r/Config.cpp
@@ -732,18 +732,18 @@ bool DynamicConfig::read_cli(int argc, char** argv, t_config_option_keys* extra,
         }
         // Store the option value.
         const bool               existing   = this->has(opt_key);
-        if (keys != nullptr && !existing) {
+        if (keys != nullptr && ! existing) {
             // Save the order of detected keys.
             keys->push_back(opt_key);
         }
         ConfigOption            *opt_base   = this->option(opt_key, true);
         ConfigOptionVectorBase  *opt_vector = opt_base->is_vector() ? static_cast<ConfigOptionVectorBase*>(opt_base) : nullptr;
         if (opt_vector) {
+			if (! existing)
+				// remove the default values
+				opt_vector->clear();
             // Vector values will be chained. Repeated use of a parameter will append the parameter or parameters
             // to the end of the value.
-			if (!existing)
-				// remove the default values
-				opt_vector->deserialize("", true);
             if (opt_base->type() == coBools)
                 static_cast<ConfigOptionBools*>(opt_base)->values.push_back(!no);
             else
diff --git a/src/libslic3r/Config.hpp b/src/libslic3r/Config.hpp
index ee4bc4e46..a7192a558 100644
--- a/src/libslic3r/Config.hpp
+++ b/src/libslic3r/Config.hpp
@@ -167,8 +167,10 @@ public:
     // Set a single vector item from either a scalar option or the first value of a vector option.vector of ConfigOptions. 
     // This function is useful to split values from multiple extrder / filament settings into separate configurations.
     virtual void set_at(const ConfigOption *rhs, size_t i, size_t j) = 0;
-
+    // Resize the vector of values, copy the newly added values from opt_default if provided.
     virtual void resize(size_t n, const ConfigOption *opt_default = nullptr) = 0;
+    // Clear the values vector.
+    virtual void clear() = 0;
 
     // Get size of this vector.
     virtual size_t size()  const = 0;
@@ -277,6 +279,8 @@ public:
         }
     }
 
+    // Clear the values vector.
+    void   clear() override { this->values.clear(); }
     size_t size()  const override { return this->values.size(); }
     bool   empty() const override { return this->values.empty(); }