From 73857703b8df3fcccd9dad28f0734d1cd9dec38b Mon Sep 17 00:00:00 2001
From: Lukas Matena <lukasmatena@seznam.cz>
Date: Wed, 15 Mar 2023 09:21:12 +0100
Subject: [PATCH] Added a check that libslic3r/I18N.hpp is not included on the
 frontend by mistake, also added a check that L macro is not defined when
 including libslic3r/I18N.hpp

---
 src/libslic3r/I18N.hpp     | 25 +++++++++++++++++++------
 src/slic3r/CMakeLists.txt  |  3 +++
 src/slic3r/GUI/GUI_App.cpp |  4 ++++
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/src/libslic3r/I18N.hpp b/src/libslic3r/I18N.hpp
index 3bf286b192..51d41a3ea1 100644
--- a/src/libslic3r/I18N.hpp
+++ b/src/libslic3r/I18N.hpp
@@ -3,6 +3,12 @@
 
 #include <string>
 
+#ifdef SLIC3R_CURRENTLY_COMPILING_GUI_MODULE
+    #ifndef SLIC3R_ALLOW_LIBSLIC3R_I18N_IN_SLIC3R
+        #error You included libslic3r/I18N.hpp into a file belonging to slic3r module.
+    #endif
+#endif
+
 namespace Slic3r {
 
 namespace I18N {
@@ -15,11 +21,18 @@ namespace I18N {
 
 } // namespace Slic3r
 
-namespace {
-	const char* L(const char* s)            { return s; }
-	std::string _u8L(const char* s)         { return Slic3r::I18N::translate(s); }
-	std::string _utf8(const char* s)        { return Slic3r::I18N::translate(s); }
-	std::string _utf8(const std::string& s) { return Slic3r::I18N::translate(s); }
-}
+// When this is included from slic3r, better do not define the translation functions.
+// Macros from slic3r/GUI/I18N.hpp should be used there.
+#ifndef SLIC3R_CURRENTLY_COMPILING_GUI_MODULE
+	#ifdef L
+	    #error L macro is defined where it shouldn't be. Didn't you include slic3r/GUI/I18N.hpp in libslic3r by mistake?
+	#endif
+	namespace {
+		const char* L(const char* s)            { return s; }
+		std::string _u8L(const char* s)         { return Slic3r::I18N::translate(s); }
+		std::string _utf8(const char* s)        { return Slic3r::I18N::translate(s); }
+		std::string _utf8(const std::string& s) { return Slic3r::I18N::translate(s); }
+	}
+#endif
 
 #endif /* slic3r_I18N_hpp_ */
diff --git a/src/slic3r/CMakeLists.txt b/src/slic3r/CMakeLists.txt
index 2ca1998e31..db8cefa995 100644
--- a/src/slic3r/CMakeLists.txt
+++ b/src/slic3r/CMakeLists.txt
@@ -344,3 +344,6 @@ if (UNIX AND NOT APPLE)
     target_include_directories(libslic3r_gui PRIVATE ${GTK${SLIC3R_GTK}_INCLUDE_DIRS})
     target_link_libraries(libslic3r_gui ${GTK${SLIC3R_GTK}_LIBRARIES} fontconfig)
 endif ()
+
+# Add a definition so that we can tell we are compiling slic3r.
+target_compile_definitions(libslic3r_gui PRIVATE SLIC3R_CURRENTLY_COMPILING_GUI_MODULE)
diff --git a/src/slic3r/GUI/GUI_App.cpp b/src/slic3r/GUI/GUI_App.cpp
index 5d3b65632c..4be6de6e1e 100644
--- a/src/slic3r/GUI/GUI_App.cpp
+++ b/src/slic3r/GUI/GUI_App.cpp
@@ -8,7 +8,11 @@
 
 // Localization headers: include libslic3r version first so everything in this file
 // uses the slic3r/GUI version (the macros will take precedence over the functions).
+// Also, there is a check that the former is not included from slic3r module.
+// This is the only place where we want to allow that, so define an override macro.
+#define SLIC3R_ALLOW_LIBSLIC3R_I18N_IN_SLIC3R
 #include "libslic3r/I18N.hpp"
+#undef SLIC3R_ALLOW_LIBSLIC3R_I18N_IN_SLIC3R
 #include "slic3r/GUI/I18N.hpp"
 
 #include <algorithm>