Add option to specify a C++ standard to ICG for parsing (#1499)

Makefile

@@ -470,6 +470,13 @@ ICG: TRICK_SYSTEM_CXXFLAGS := $(subst -isystem,-I,$(TRICK_SYSTEM_CXXFLAGS))
 ICG: $(ICG_EXE)
 	$(ICG_EXE) -f -s -m -n ${TRICK_CXXFLAGS} ${TRICK_SYSTEM_CXXFLAGS} ${TRICK_HOME}/include/trick/files_to_ICG.hh
 
+
+ICG_EXE: force-icg-build
+
+.PHONY: force-icg-build
+force-icg-build: 
+	$(MAKE) -C trick_source/codegen/Interface_Code_Gen
+
 # This builds a tricklib share library.
 trick_lib: $(SIM_SERV_DIRS) $(UTILS_DIRS) | $(TRICK_LIB_DIR)
 	${TRICK_CXX} $(SHARED_LIB_OPT) -o ${TRICK_LIB_DIR}/libtrick.so $(SIM_SERV_OBJS) $(UTILS_OBJS)

docs/documentation/building_a_simulation/Making-the-Simulation.md

@@ -91,6 +91,16 @@ Edit a file called "S_overrides.mk". Append to the TRICK_EXCLUDE variable.
 TRICK_EXCLUDE += /path/to/exclude:/another/path/to/exclude
 ```
 
+### Example how to set a C++ standard for ICG and compilation
+
+Edit a file called "S_overrides.mk". Append to the TRICK_CXXFLAGS variable.
+
+```
+TRICK_CXXFLAGS += -std=c++11
+```
+
+Valid options are c++11, c++14, c++17, or c++20. ICG will parse to c++17 by default, or the newest supported version if c++17 is not availible. 
+
 ## Cleaning Up
 
 There are several levels of clean.

trick_source/codegen/Interface_Code_Gen/main.cpp

@@ -38,6 +38,7 @@ llvm::cl::opt<bool> units_truth_is_scary("units-truth-is-scary", llvm::cl::desc(
 llvm::cl::opt<bool> sim_services_flag("sim_services", llvm::cl::desc("Gernerate io_src for Trick core headers"));
 llvm::cl::opt<bool> force("force", llvm::cl::desc("Force all io_src files to be generated"));
 llvm::cl::opt<int> attr_version("v", llvm::cl::desc("Select version of attributes to produce.  10 and 13 are valid"), llvm::cl::init(10));
+llvm::cl::opt<std::string> standard_version("std", llvm::cl::desc("Set the C++ standard to use when parsing. c++11, c++14, c++17, and c++20 are valid. Default is c++17 or the newest supported by your LLVM version."), llvm::cl::init(""), llvm::cl::ZeroOrMore);
 llvm::cl::opt<int> debug_level("d", llvm::cl::desc("Set debug level"), llvm::cl::init(0), llvm::cl::ZeroOrMore);
 llvm::cl::opt<bool> create_map("m", llvm::cl::desc("Create map files"), llvm::cl::init(false));
 llvm::cl::opt<std::string> output_dir("o", llvm::cl::desc("Output directory"));
@@ -57,12 +58,48 @@ void set_lang_opts(clang::CompilerInstance & ci) {
     ci.getLangOpts().Bool = true ;
     ci.getLangOpts().WChar = true ;
     ci.getLangOpts().CPlusPlus = true ;
-    ci.getLangOpts().CPlusPlus11 = true ;
     ci.getLangOpts().CXXOperatorNames = true ;
+
+    // Always use at least C++11
+    ci.getLangOpts().CPlusPlus11 = true ;
+
+
+#if (LIBCLANG_MAJOR < 6)
+    // Check if standard_version was specified and if it's a version that is supported by this libclang
+    if (standard_version != "") {
+        if (standard_version == "c++11") {
+            // Nothing to be done here really
+        } else if (standard_version == "c++14" || standard_version == "c++17" || standard_version == "c++20") {
+            std::cerr << "C++ standard " << standard_version << " is not supported by this version of Clang." << std::endl;
+        } else {
+            std::cerr << "Invalid C++ standard version specified:" << standard_version << std::endl;
+        }
+    }
+#endif
+
+    // Activate C++14 parsing
 #if (LIBCLANG_MAJOR >= 6)
     ci.getLangOpts().CPlusPlus14 = true ;
-    ci.getLangOpts().DoubleSquareBracketAttributes = true ;
+    ci.getLangOpts().DoubleSquareBracketAttributes = true ;    
 #endif
+
+#if (LIBCLANG_MAJOR >= 6 && LIBCLANG_MAJOR < 10)
+    // Check if standard_version was specified and if it's a version that is supported by this libclang
+    if (standard_version != "") {
+        if (standard_version == "c++11") {
+            // Turn off c++14, c++11 is already on
+            ci.getLangOpts().CPlusPlus14 = false ;
+        } else if (standard_version == "c++14") {
+            // Nothing to be done here
+        }else if (standard_version == "c++17" || standard_version == "c++20") {
+            std::cerr << "C++ standard " << standard_version << " is not supported by this version of Clang." << std::endl;
+        } else {
+            std::cerr << "Invalid C++ standard version specified:" << standard_version << std::endl;
+        }
+    }
+#endif
+
+
     // Activate C++17 parsing
 #ifdef TRICK_GCC_VERSION
 const char * gcc_version = TRICK_GCC_VERSION;
@@ -73,6 +110,24 @@ const char * gcc_version = "";
 #if (LIBCLANG_MAJOR >= 10)
     ci.getLangOpts().GNUCVersion = gccVersionToIntOrDefault(gcc_version, 40805);
     ci.getLangOpts().CPlusPlus17 = true ;
+
+    // Check if standard_version was specified and if it's a version that is supported by this libclang
+    if (standard_version != "") {
+        if (standard_version == "c++11") {
+            ci.getLangOpts().CPlusPlus14 = false ;
+            ci.getLangOpts().CPlusPlus17 = false ;
+        } else if (standard_version == "c++14") {
+            ci.getLangOpts().CPlusPlus17 = false ;
+        } else if (standard_version == "c++17" ) {
+            // Nothing to do here
+        } else if (standard_version == "c++20") {
+            // It looks like Clang10 was the first to offer the "c++20" flag, but there was partial support before that.
+            // (https://clang.llvm.org/cxx_status.html)
+            ci.getLangOpts().CPlusPlus20 = true ;
+        } else {
+            std::cerr << "Invalid C++ standard version specified:" << standard_version << std::endl;
+        }
+    }
 #endif
 }
 /**