Moved if constexpr to constexpr part and out of STL

talk/morelanguage/constexpr.tex

@@ -121,6 +121,33 @@
   \end{cppcode*}
 \end{frame}
 
+\begin{frame}[fragile]
+  \frametitlecpp[17]{compile-time branches}
+  \begin{block}{{\it if constexpr}}
+    \begin{itemize}
+    \item takes a \cppinline{constexpr} expression as condition
+    \item evaluates at compile time
+    \item key benefit: the discarded branch can contain invalid code
+    \end{itemize}
+  \end{block}
+  \begin{exampleblock}{Example code}
+    \small
+    \begin{cppcode*}{}
+      template <typename T>
+      auto remove_ptr(T t) {
+        if constexpr (std::is_pointer_v<T>) {
+          return *t;
+        } else {
+          return t;
+        }
+      }
+      int i = ...; int *j = ...;
+      int r = remove_ptr(i);  // equivalent to i
+      int q = remove_ptr(j);  // equivalent to *j
+    \end{cppcode*}
+  \end{exampleblock}
+\end{frame}
+
 \begin{frame}[fragile]
   \frametitlecpp[20]{Immediate functions}
   \begin{block}{Motivation}

talk/morelanguage/morestl.tex

@@ -424,30 +424,3 @@
     \end{cppcode*}
   \end{exampleblock}
 \end{frame}
-
-\begin{frame}[fragile]
-  \frametitlecpp[17]{compile-time branches}
-  \begin{block}{{\it if constexpr}}
-    \begin{itemize}
-    \item takes a \cppinline{constexpr} expression as condition
-    \item evaluates at compile time
-    \item key benefit: the discarded branch can contain invalid code
-    \end{itemize}
-  \end{block}
-  \begin{exampleblock}{Example code}
-    \small
-    \begin{cppcode*}{}
-      template <typename T>
-      auto remove_ptr(T t) {
-        if constexpr (std::is_pointer_v<T>) {
-          return *t;
-        } else {
-          return t;
-        }
-      }
-      int i = ...; int *j = ...;
-      int r = remove_ptr(i);  // equivalent to i
-      int q = remove_ptr(j);  // equivalent to *j
-    \end{cppcode*}
-  \end{exampleblock}
-\end{frame}