c++: if constexpr

README.adoc

@@ -12983,7 +12983,10 @@ Programs under link:userland/cpp/[] are examples of https://en.wikipedia.org/wik
 * link:userland/cpp/empty.cpp[]
 * link:userland/cpp/hello.cpp[]
 * templates
-** link:userland/cpp/template.cpp[]
+** link:userland/cpp/template.cpp[]: basic example
+** link:userland/cpp/if_constexpr.cpp[]: C++17 `if constexpr`
+*** https://stackoverflow.com/questions/12160765/if-else-at-compile-time-in-c/54647315#54647315
+*** https://stackoverflow.com/questions/37617677/implementing-a-compile-time-static-if-logic-for-different-string-types-in-a-co
 
 [[cpp-multithreading]]
 ==== C++ multithreading

userland/cpp/if_constexpr.cpp

@@ -0,0 +1,23 @@
+// https://cirosantilli.com/linux-kernel-module-cheat#cpp
+
+#if __cplusplus >= 201703L
+#include <cassert>
+#include <type_traits>
+
+template <class T>
+struct MyClass {
+    int myFunc() {
+        if constexpr(std::is_integral<T>())
+            return 1;
+        else
+            return 2;
+    }
+};
+#endif
+
+int main() {
+#if __cplusplus >= 201703L
+    assert(MyClass<int>().myFunc() == 1);
+    assert(MyClass<float>().myFunc() == 2);
+#endif
+}