make: require C++20

needed by pdlp/

makefiles/Makefile.unix.mk

@@ -110,7 +110,7 @@ DEBUG = -O4 -DNDEBUG
 JNIDEBUG = -O1 -DNDEBUG
 
 ifeq ($(PLATFORM),LINUX)
-  CCC = g++ -fPIC -std=c++17 -fwrapv
+  CCC = g++ -fPIC -std=c++20 -fwrapv
   DYNAMIC_LD = g++ -shared
   DYNAMIC_LDFLAGS = -Wl,-rpath,\"\\\$$\$$ORIGIN\"
 
@@ -142,7 +142,7 @@ ifeq ($(PLATFORM),LINUX)
   POST_LIB =
   LINK_FLAGS = \
  -Wl,-rpath,'$$ORIGIN' \
- -Wl,-rpath,'$$ORIGIN/../lib' 
+ -Wl,-rpath,'$$ORIGIN/../lib'
 
   PYTHON_LDFLAGS = \
  -Wl,-rpath,'$$ORIGIN' \
@@ -153,7 +153,7 @@ ifeq ($(PLATFORM),LINUX)
 endif  # ifeq ($(PLATFORM),LINUX)
 ifeq ($(PLATFORM),MACOSX)
   MAC_VERSION = -mmacosx-version-min=$(MAC_MIN_VERSION)
-  CCC = clang++ -fPIC -std=c++17  $(MAC_VERSION) -stdlib=libc++
+  CCC = clang++ -fPIC -std=c++20  $(MAC_VERSION) -stdlib=libc++
   DYNAMIC_LD = clang++ -dynamiclib -undefined dynamic_lookup \
   $(MAC_VERSION) \
  -Wl,-search_paths_first \

makefiles/Makefile.win.mk

@@ -101,7 +101,7 @@ TASKKILL = taskkill
 
 # Compilation macros.
 DEBUG=/O2 -DNDEBUG
-CCC=cl /std:c++17 /EHsc /MD /nologo -nologo $(SYSCFLAGS) /D__WIN32__ /DPSAPI_VERSION=1 \
+CCC=cl /std:c++20 /EHsc /MD /nologo -nologo $(SYSCFLAGS) /D__WIN32__ /DPSAPI_VERSION=1 \
  /DNOMINMAX /DWIN32_LEAN_AND_MEAN=1 /D_CRT_SECURE_NO_WARNINGS
 
 PYTHON_VERSION = $(WINDOWS_PYTHON_VERSION)

or-tools.code-workspace

@@ -102,7 +102,7 @@
 			"${workspaceRoot}/ortools/gen",
 			"${workspaceRoot}/dependencies/install/include",
 		],
-		"C_Cpp.default.cppStandard": "c++17",
+		"C_Cpp.default.cppStandard": "c++20",
 		"C_Cpp.default.cStandard": "c11",
 		"C_Cpp.default.defines": [
 			"USE_BOP",
@@ -122,10 +122,10 @@
 			"editor.tabSize": 2,
 		},
 		"[csharp]": {
-			"editor.tabSize": 2,       
+			"editor.tabSize": 2,
 		},
 		"[java]": {
-			"editor.tabSize": 2,       
+			"editor.tabSize": 2,
 		},
 		"[python]": {
 			"editor.tabSize": 4,
@@ -134,4 +134,4 @@
     "maven.view": "hierarchical",
     "git.ignoreLimitWarning": true,
 	}
-}
+}

tools/Makefile.cc.java.dotnet

@@ -64,7 +64,7 @@ ifeq ($(SYSTEM),unix)
   endif # ifeq($(OS),Darwin)
   CXX_BIN := $(shell command -v $(CXX) 2> /dev/null)
   DEBUG = -O4 -DNDEBUG
-  CXXFLAGS = -fPIC -std=c++17 $(DEBUG) \
+  CXXFLAGS = -fPIC -std=c++20 $(DEBUG) \
  -I$(INC_DIR) -I. $(ARCH) -Wno-deprecated \
  -DUSE_BOP -DUSE_GLOP \
  -DUSE_CBC -DUSE_CLP \
@@ -123,7 +123,7 @@ ifeq ($(SYSTEM),win)
   # so we ship which.exe and use it
   CXX_BIN := $(shell $(WHICH) $(CXX) 2> NUL)
   DEBUG = /O2 -DNDEBUG
-  CXXFLAGS = /std:c++17 /EHsc /MD /nologo /D_SILENCE_STDEXT_HASH_DEPRECATION_WARNINGS -nologo $(DEBUG) \
+  CXXFLAGS = /std:c++20 /EHsc /MD /nologo /D_SILENCE_STDEXT_HASH_DEPRECATION_WARNINGS -nologo $(DEBUG) \
     /DPSAPI_VERSION=1 /D__WIN32__ /DNOMINMAX /DWIN32_LEAN_AND_MEAN=1 /D_CRT_SECURE_NO_WARNINGS \
     /DGOOGLE_GLOG_DLL_DECL= \
     /I$(INC_DIR)\\src\\windows /I$(INC_DIR) /I. \