Fix documentation

source/examples/HotReloadDemo/Shared/CppWidgetApi.h

@@ -1,47 +1,88 @@
-/* CppWidgetApi.h -- a C++ (not extern "C") surface living alongside
+/**
+ * @file CppWidgetApi.h
+ * @brief A C++ (not extern "C") surface living alongside
  * PluginApi.h's plain C one, in the SAME plugin build. Every member
  * function below keeps its real, compiler-mangled name; nothing here
  * needs special handling by source/HotReload, which classifies
  * symbols by their type and section, never by what their name looks
- * like -- see hot_reload.h's "REQUIREMENTS ON A HOT-RELOADABLE
- * MODULE" and README.md's "Hot reloading C++ symbols" for the full
- * picture.
+ * like -- see the "Requirements on a hot-reloadable module" section of
+ * hot_reload.h and the "Hot reloading C++ symbols" section of
+ * source/HotReload/README.md for the full picture.
  *
  * The two methods below are reached two different ways from
  * Host/Main.cpp, deliberately: see that file's comments for why.
  */
 #pragma once
 
+/**
+ * @brief A small C++ class whose members are defined in the plugin, not the host.
+ *
+ * Each member below keeps its real, compiler-mangled name and is reached a different way from
+ * Host/Main.cpp -- through the vtable, through a manually resolved mangled name, and (for the
+ * operator) not at all -- to show that all of them patch like any plain C function.
+ */
 class CppWidget
 {
 public:
+	/**
+	 * @brief Virtual, so that destroying a widget through a base pointer works across the
+	 *        boundary.
+	 */
 	virtual ~CppWidget() = default;
 
-	/* Virtual: Host/Main.cpp calls this through ordinary C++
+	/**
+	 * @brief Scales its input, through a virtual call.
+	 *
+	 * Virtual: Host/Main.cpp calls this through ordinary C++
 	 * polymorphic dispatch (widget->virtualTick(x)) and needs no
 	 * manual symbol lookup at all -- the call compiles down to an
 	 * indirect call through the object's vtable slot, not a direct
 	 * reference to this specific symbol, so it needs no link-time
-	 * dependency on whichever plugin build actually defines it. */
+	 * dependency on whichever plugin build actually defines it.
+	 *
+	 * @param input The value to scale.
+	 * @return V1: `input * 2`. V2: `input * 3`.
+	 */
 	virtual int virtualTick(int input);
 
-	/* An ordinary out-of-line method. Calling this as widget->tick(x)
+	/**
+	 * @brief Scales its input, through an ordinary out-of-line method.
+	 *
+	 * Calling this as widget->tick(x)
 	 * would compile to a direct call to CppWidget::tick's own mangled
 	 * symbol, which would need the Host to link against a plugin
 	 * build at build time -- exactly what hot-reloading a plugin
 	 * means avoiding. So Host/Main.cpp instead resolves it manually
 	 * by its mangled name via hot_reload_get_symbol(), the same way
-	 * it resolves PluginApi.h's plain C functions. */
+	 * it resolves PluginApi.h's plain C functions.
+	 *
+	 * @param input The value to scale.
+	 * @return V1: `input * 2`. V2: `input * 3`.
+	 */
 	int tick(int input);
 
-	/* An overloaded operator: mechanically just a function with an
+	/**
+	 * @brief An overloaded operator.
+	 *
+	 * Mechanically just a function with an
 	 * unusual mangled name, reached the same manual way as tick()
-	 * above. */
+	 * above.
+	 *
+	 * @param other Ignored; the operator only prints which build it is.
+	 * @return A new, empty widget.
+	 */
 	CppWidget operator+(const CppWidget& other) const;
 };
 
-/* The one entry point Host/Main.cpp looks up by a plain, human-typed
+/**
+ * @brief Creates a widget.
+ *
+ * The one entry point Host/Main.cpp looks up by a plain, human-typed
  * name -- extern "C" here for exactly the reason hot_reload.h
  * recommends it: something to hand a human-readable name to, without
- * needing to know or hardcode a mangled string. */
+ * needing to know or hardcode a mangled string.
+ *
+ * @return A new widget. The caller owns it and must `delete` it (safe across the plugin
+ *         boundary here because host and plugin share one C++ runtime and allocator).
+ */
 extern "C" CppWidget* make_cpp_widget();

source/examples/HotReloadDemo/Shared/PluginApi.h

@@ -1,4 +1,6 @@
-/* PluginApi.h -- the contract PluginV1 and PluginV2 both implement,
+/**
+ * @file PluginApi.h
+ * @brief The contract PluginV1 and PluginV2 both implement,
  * and the Host loads by name. Every function here follows
  * cpp-style-guide.md section 11's rule for anything loaded at runtime:
  * plain C linkage, no classes or exceptions crossing the boundary.
@@ -15,31 +17,64 @@ extern "C"
 {
 #endif
 
-	/* Changes behavior between V1 and V2 -- watch this one get
-	 * HOT_RELOAD_SYMBOL_PATCHED. */
+	/**
+	 * @brief Scales its input, and prints which build it is.
+	 *
+	 * Changes behavior between V1 and V2 -- watch this one get
+	 * HOT_RELOAD_SYMBOL_PATCHED.
+	 *
+	 * @param input The value to scale.
+	 * @return V1: `input * 2`. V2: `input * 3`.
+	 */
 	int plugin_tick(int input);
 
-	/* Only in V1, gone in V2 -- watch this one get
-	 * HOT_RELOAD_SYMBOL_REMOVED, and the Host's stub take over for any
-	 * call still aimed at it afterwards. */
+	/**
+	 * @brief A feature that exists only in V1.
+	 *
+	 * Gone in V2 -- watch this one get HOT_RELOAD_SYMBOL_REMOVED, and the
+	 * Host's stub take over for any call still aimed at it afterwards.
+	 *
+	 * @param input The value to echo.
+	 * @return @p input, unchanged.
+	 */
 	int plugin_legacy_feature(int input);
 
-	/* Only in V2 -- watch this one get HOT_RELOAD_SYMBOL_ADDED, then
-	 * get called for the first time right after. */
+	/**
+	 * @brief A feature that exists only in V2.
+	 *
+	 * Watch this one get HOT_RELOAD_SYMBOL_ADDED, then get called for the
+	 * first time right after.
+	 *
+	 * @param input The value to scale.
+	 * @return `input * 10`.
+	 */
 	int plugin_new_feature(int input);
 
 #if defined(__GNUC__) || defined(__clang__)
-	/* Deliberately too small to safely hold a jump on any of this
-	 * library's backends (its patchable-function-entry padding is
-	 * overridden down to zero) -- watch this one get
-	 * HOT_RELOAD_SYMBOL_SKIPPED_TOO_SMALL rather than corrupt whatever
-	 * comes after it. MSVC has no equivalent per-function override
-	 * this demo could apply, so this one only exists on GCC/Clang.
+	/**
+	 * @brief An empty function, too small to hold the jump this library writes.
+	 *
+	 * Its patchable-function-entry padding is overridden down to zero, so
+	 * all that is left is the compiled empty body -- a handful of bytes,
+	 * fewer than the jump any of this library's backends writes on x86-64
+	 * and ARM64 at any optimization level. Watch this one get
+	 * HOT_RELOAD_SYMBOL_SKIPPED_TOO_SMALL rather than corrupt whatever comes
+	 * after it.
+	 *
+	 * Two configurations cannot promise "too small": unoptimized 32-bit x86
+	 * (its jump is only 5 bytes, which even an empty unoptimized function
+	 * reaches), and Windows, where a PE image carries no per-function size
+	 * and the library can only estimate one from the distance to the next
+	 * export. MSVC has no equivalent per-function override this demo could
+	 * apply, so this one only exists on GCC/Clang.
 	 */
-	__attribute__((patchable_function_entry(0))) int plugin_tiny_function(int input);
+	__attribute__((patchable_function_entry(0))) void plugin_tiny_function(void);
 #endif
 
-	/* An exported VARIABLE, not a function, sitting right next to
+	/**
+	 * @brief The build's version number: 1 in V1, 2 in V2.
+	 *
+	 * An exported VARIABLE, not a function, sitting right next to
 	 * real functions in the same library and changing value between
 	 * V1 and V2 just like plugin_tick's behavior does -- watch this
 	 * one get HOT_RELOAD_SYMBOL_SKIPPED_NOT_CODE. This is the