Add copy elision

cdervis · cdervis · commit 2e402400a5dd · 2026-03-25T21:05:01.000+01:00
diff --git a/content/guaranteed-copy-elision.md b/content/guaranteed-copy-elision.md
@@ -0,0 +1,36 @@
+---
+execute: true
+---
+
+## What It Does
+
+In C++17 and newer, returning a [prvalue](https://en.cppreference.com/w/cpp/language/value_category.html) of the same type as the function return type,
+or initializing an object from a prvalue, is guaranteed to construct the object directly in its destination.
+No copy or move constructor is called or required to exist.
+
+## Why It Matters
+
+Before C++17, copy elision was an optimization that compilers were permitted but not required to perform.
+Code relying on elision could fail to compile if the copy/move constructor was deleted or inaccessible.
+C++17 mandates elision in these cases, making prvalue semantics part of the language definition.
+
+## Example
+
+```cpp
+#include <print>
+
+struct Widget {
+    Widget() { std::println("constructed"); }
+    Widget(const Widget&) = delete;
+    Widget(Widget&&) = delete;
+};
+
+Widget make() {
+    return Widget();
+}
+
+int main() {
+    auto w = make();
+    std::println("done");
+}
+```
