[PATCH] utils: ipc: Fix event functions with no parameters

[Laurent Pinchart]

Hi Paul,

On Tue, Apr 09, 2024 at 07:40:44PM +0900, Paul Elder wrote:
> If an event function is defined with no parameters, there would be a
> compilation error complaining about unused parameters in the generated
> code for the data and dataSize parameters that would normally correspond
> to serialized data. Fix this by simply marking the parameters as
> maybe_unused.

There's another similar issue when using async methods with no
parameters in the IPA interface. It can be reproduced with the following
test:

diff --git a/include/libcamera/ipa/vimc.mojom b/include/libcamera/ipa/vimc.mojom
index dd991f7e70c9..28dfd878ea39 100644
--- a/include/libcamera/ipa/vimc.mojom
+++ b/include/libcamera/ipa/vimc.mojom
@@ -48,6 +48,7 @@ interface IPAVimcInterface {
 	 * handle parameters at runtime.
 	 */
 	[async] fillParamsBuffer(uint32 frame, uint32 bufferId);
+	[async] test();
 };

 interface IPAVimcEventInterface {
diff --git a/src/ipa/vimc/vimc.cpp b/src/ipa/vimc/vimc.cpp
index 2c255778990a..e62cf9f22089 100644
--- a/src/ipa/vimc/vimc.cpp
+++ b/src/ipa/vimc/vimc.cpp
@@ -49,6 +49,8 @@ public:
 	void queueRequest(uint32_t frame, const ControlList &controls) override;
 	void fillParamsBuffer(uint32_t frame, uint32_t bufferId) override;

+	void test();
+
 private:
 	void initTrace();
 	void trace(enum ipa::vimc::IPAOperationCode operation);

The result is the following compilation error:

src/libcamera/proxy/vimc_ipa_proxy.cpp: In member function ‘void libcamera::ipa::vimc::IPAProxyVimc::testThread()’:
src/libcamera/proxy/vimc_ipa_proxy.cpp:537:70: error: expected primary-expression before ‘)’ token
  537 |         proxy_.invokeMethod(&ThreadProxy::test, ConnectionTypeQueued,);
      | 

> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> ---
>  .../generators/libcamera_templates/module_ipa_proxy.cpp.tmpl  | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/utils/ipc/generators/libcamera_templates/module_ipa_proxy.cpp.tmpl b/utils/ipc/generators/libcamera_templates/module_ipa_proxy.cpp.tmpl
> index c37c4941..238cf4a5 100644
> --- a/utils/ipc/generators/libcamera_templates/module_ipa_proxy.cpp.tmpl
> +++ b/utils/ipc/generators/libcamera_templates/module_ipa_proxy.cpp.tmpl
> @@ -235,8 +235,8 @@ void {{proxy_name}}::recvMessage(const IPCMessage &data)
>  }
>  
>  void {{proxy_name}}::{{method.mojom_name}}IPC(
> -	std::vector<uint8_t>::const_iterator data,
> -	size_t dataSize,
> +	[[maybe_unused]] std::vector<uint8_t>::const_iterator data,
> +	[[maybe_unused]] size_t dataSize,
>  	[[maybe_unused]] const std::vector<SharedFD> &fds)
>  {
>  {%- for param in method.parameters %}

-- 
Regards,

Laurent Pinchart