element: Implement linking functions manually for better error reporting

Fixes https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/issues/318

gstreamer/Gir.toml

@@ -1038,13 +1038,13 @@ manual_traits = ["ElementExtManual"]
     # but gir considers these methods on `ElementExtManual` in the docs.
     [[object.function]]
     name = "link_many"
-    ignore = true
+    manual = true
     [[object.function]]
     name = "unlink_many"
-    ignore = true
+    manual = true
     [[object.function]]
     name = "register"
-    ignore = true
+    manual = true
 
     [[object.function]]
     name = "call_async"
@@ -1094,38 +1094,34 @@ manual_traits = ["ElementExtManual"]
         [object.function.return]
         bool_return_is_error = "Failed to remove pad"
 
+    # Manual implementations with better error reporting
     [[object.function]]
     name = "link"
-        [object.function.return]
+    manual = true
-        bool_return_is_error = "Failed to link elements"
 
     [[object.function]]
     name = "link_filtered"
+    manual = true
         [[object.function.parameter]]
         name = "filter"
         # Can use `link` instead
         nullable = false
-        [object.function.return]
-        bool_return_is_error = "Failed to link elements"
 
     [[object.function]]
     name = "link_pads"
-        [object.function.return]
+    manual = true
-        bool_return_is_error = "Failed to link pads"
 
     [[object.function]]
     name = "link_pads_filtered"
+    manual = true
         [[object.function.parameter]]
         name = "filter"
         # Can use `link` instead
         nullable = false
-        [object.function.return]
-        bool_return_is_error = "Failed to link pads"
 
     [[object.function]]
     name = "link_pads_full"
-        [object.function.return]
+    manual = true
-        bool_return_is_error = "Failed to link pads"
 
     [[object.function]]
     name = "set_clock"

gstreamer/src/auto/element.rs

@@ -11,7 +11,6 @@ use crate::Context;
 use crate::ElementFactory;
 use crate::Object;
 use crate::Pad;
-use crate::PadLinkCheck;
 use crate::PadTemplate;
 use crate::State;
 use crate::StateChange;
@@ -147,42 +146,6 @@ pub trait ElementExt: 'static {
     #[doc(alias = "gst_element_is_locked_state")]
     fn is_locked_state(&self) -> bool;
 
-    #[doc(alias = "gst_element_link")]
-    fn link(&self, dest: &impl IsA<Element>) -> Result<(), glib::error::BoolError>;
-
-    #[doc(alias = "gst_element_link_filtered")]
-    fn link_filtered(
-        &self,
-        dest: &impl IsA<Element>,
-        filter: &Caps,
-    ) -> Result<(), glib::error::BoolError>;
-
-    #[doc(alias = "gst_element_link_pads")]
-    fn link_pads(
-        &self,
-        srcpadname: Option<&str>,
-        dest: &impl IsA<Element>,
-        destpadname: Option<&str>,
-    ) -> Result<(), glib::error::BoolError>;
-
-    #[doc(alias = "gst_element_link_pads_filtered")]
-    fn link_pads_filtered(
-        &self,
-        srcpadname: Option<&str>,
-        dest: &impl IsA<Element>,
-        destpadname: Option<&str>,
-        filter: &Caps,
-    ) -> Result<(), glib::error::BoolError>;
-
-    #[doc(alias = "gst_element_link_pads_full")]
-    fn link_pads_full(
-        &self,
-        srcpadname: Option<&str>,
-        dest: &impl IsA<Element>,
-        destpadname: Option<&str>,
-        flags: PadLinkCheck,
-    ) -> Result<(), glib::error::BoolError>;
-
     #[doc(alias = "gst_element_lost_state")]
     fn lost_state(&self);
 
@@ -475,96 +438,6 @@ impl<O: IsA<Element>> ElementExt for O {
         }
     }
 
-    fn link(&self, dest: &impl IsA<Element>) -> Result<(), glib::error::BoolError> {
-        unsafe {
-            glib::result_from_gboolean!(
-                ffi::gst_element_link(
-                    self.as_ref().to_glib_none().0,
-                    dest.as_ref().to_glib_none().0
-                ),
-                "Failed to link elements"
-            )
-        }
-    }
-
-    fn link_filtered(
-        &self,
-        dest: &impl IsA<Element>,
-        filter: &Caps,
-    ) -> Result<(), glib::error::BoolError> {
-        unsafe {
-            glib::result_from_gboolean!(
-                ffi::gst_element_link_filtered(
-                    self.as_ref().to_glib_none().0,
-                    dest.as_ref().to_glib_none().0,
-                    filter.to_glib_none().0
-                ),
-                "Failed to link elements"
-            )
-        }
-    }
-
-    fn link_pads(
-        &self,
-        srcpadname: Option<&str>,
-        dest: &impl IsA<Element>,
-        destpadname: Option<&str>,
-    ) -> Result<(), glib::error::BoolError> {
-        unsafe {
-            glib::result_from_gboolean!(
-                ffi::gst_element_link_pads(
-                    self.as_ref().to_glib_none().0,
-                    srcpadname.to_glib_none().0,
-                    dest.as_ref().to_glib_none().0,
-                    destpadname.to_glib_none().0
-                ),
-                "Failed to link pads"
-            )
-        }
-    }
-
-    fn link_pads_filtered(
-        &self,
-        srcpadname: Option<&str>,
-        dest: &impl IsA<Element>,
-        destpadname: Option<&str>,
-        filter: &Caps,
-    ) -> Result<(), glib::error::BoolError> {
-        unsafe {
-            glib::result_from_gboolean!(
-                ffi::gst_element_link_pads_filtered(
-                    self.as_ref().to_glib_none().0,
-                    srcpadname.to_glib_none().0,
-                    dest.as_ref().to_glib_none().0,
-                    destpadname.to_glib_none().0,
-                    filter.to_glib_none().0
-                ),
-                "Failed to link pads"
-            )
-        }
-    }
-
-    fn link_pads_full(
-        &self,
-        srcpadname: Option<&str>,
-        dest: &impl IsA<Element>,
-        destpadname: Option<&str>,
-        flags: PadLinkCheck,
-    ) -> Result<(), glib::error::BoolError> {
-        unsafe {
-            glib::result_from_gboolean!(
-                ffi::gst_element_link_pads_full(
-                    self.as_ref().to_glib_none().0,
-                    srcpadname.to_glib_none().0,
-                    dest.as_ref().to_glib_none().0,
-                    destpadname.to_glib_none().0,
-                    flags.into_glib()
-                ),
-                "Failed to link pads"
-            )
-        }
-    }
-
     fn lost_state(&self) {
         unsafe {
             ffi::gst_element_lost_state(self.as_ref().to_glib_none().0);

gstreamer/src/element.rs

@@ -39,7 +39,9 @@ impl Element {
                         e[0].as_ref().to_glib_none().0,
                         e[1].as_ref().to_glib_none().0,
                     ),
-                    "Failed to link elements"
+                    "Failed to link elements '{}' and '{}'",
+                    e[0].as_ref().name(),
+                    e[1].as_ref().name(),
                 )?;
             }
         }
@@ -268,6 +270,42 @@ pub trait ElementExtManual: 'static {
     #[doc(alias = "get_request_pad")]
     #[doc(alias = "gst_element_request_pad_simple")]
     fn request_pad_simple(&self, name: &str) -> Option<Pad>;
+
+    #[doc(alias = "gst_element_link")]
+    fn link(&self, dest: &impl IsA<Element>) -> Result<(), glib::error::BoolError>;
+
+    #[doc(alias = "gst_element_link_filtered")]
+    fn link_filtered(
+        &self,
+        dest: &impl IsA<Element>,
+        filter: &crate::Caps,
+    ) -> Result<(), glib::error::BoolError>;
+
+    #[doc(alias = "gst_element_link_pads")]
+    fn link_pads(
+        &self,
+        srcpadname: Option<&str>,
+        dest: &impl IsA<Element>,
+        destpadname: Option<&str>,
+    ) -> Result<(), glib::error::BoolError>;
+
+    #[doc(alias = "gst_element_link_pads_filtered")]
+    fn link_pads_filtered(
+        &self,
+        srcpadname: Option<&str>,
+        dest: &impl IsA<Element>,
+        destpadname: Option<&str>,
+        filter: &crate::Caps,
+    ) -> Result<(), glib::error::BoolError>;
+
+    #[doc(alias = "gst_element_link_pads_full")]
+    fn link_pads_full(
+        &self,
+        srcpadname: Option<&str>,
+        dest: &impl IsA<Element>,
+        destpadname: Option<&str>,
+        flags: crate::PadLinkCheck,
+    ) -> Result<(), glib::error::BoolError>;
 }
 
 impl<O: IsA<Element>> ElementExtManual for O {
@@ -793,6 +831,133 @@ impl<O: IsA<Element>> ElementExtManual for O {
             }
         }
     }
+
+    fn link(&self, dest: &impl IsA<Element>) -> Result<(), glib::error::BoolError> {
+        unsafe {
+            glib::result_from_gboolean!(
+                ffi::gst_element_link(
+                    self.as_ref().to_glib_none().0,
+                    dest.as_ref().to_glib_none().0
+                ),
+                "Failed to link elements '{}' and '{}'",
+                self.as_ref().name(),
+                dest.as_ref().name(),
+            )
+        }
+    }
+
+    fn link_filtered(
+        &self,
+        dest: &impl IsA<Element>,
+        filter: &crate::Caps,
+    ) -> Result<(), glib::error::BoolError> {
+        unsafe {
+            glib::result_from_gboolean!(
+                ffi::gst_element_link_filtered(
+                    self.as_ref().to_glib_none().0,
+                    dest.as_ref().to_glib_none().0,
+                    filter.to_glib_none().0
+                ),
+                "Failed to link elements '{}' and '{}' with filter '{:?}'",
+                self.as_ref().name(),
+                dest.as_ref().name(),
+                filter,
+            )
+        }
+    }
+
+    fn link_pads(
+        &self,
+        srcpadname: Option<&str>,
+        dest: &impl IsA<Element>,
+        destpadname: Option<&str>,
+    ) -> Result<(), glib::error::BoolError> {
+        unsafe {
+            glib::result_from_gboolean!(
+                ffi::gst_element_link_pads(
+                    self.as_ref().to_glib_none().0,
+                    srcpadname.to_glib_none().0,
+                    dest.as_ref().to_glib_none().0,
+                    destpadname.to_glib_none().0
+                ),
+                "Failed to link pads '{}' and '{}'",
+                if let Some(srcpadname) = srcpadname {
+                    format!("{}:{}", self.as_ref().name(), srcpadname)
+                } else {
+                    format!("{}:*", self.as_ref().name())
+                },
+                if let Some(destpadname) = destpadname {
+                    format!("{}:{}", dest.as_ref().name(), destpadname)
+                } else {
+                    format!("{}:*", dest.as_ref().name())
+                },
+            )
+        }
+    }
+
+    fn link_pads_filtered(
+        &self,
+        srcpadname: Option<&str>,
+        dest: &impl IsA<Element>,
+        destpadname: Option<&str>,
+        filter: &crate::Caps,
+    ) -> Result<(), glib::error::BoolError> {
+        unsafe {
+            glib::result_from_gboolean!(
+                ffi::gst_element_link_pads_filtered(
+                    self.as_ref().to_glib_none().0,
+                    srcpadname.to_glib_none().0,
+                    dest.as_ref().to_glib_none().0,
+                    destpadname.to_glib_none().0,
+                    filter.to_glib_none().0
+                ),
+                "Failed to link pads '{}' and '{}' with filter '{:?}'",
+                if let Some(srcpadname) = srcpadname {
+                    format!("{}:{}", self.as_ref().name(), srcpadname)
+                } else {
+                    format!("{}:*", self.as_ref().name())
+                },
+                if let Some(destpadname) = destpadname {
+                    format!("{}:{}", dest.as_ref().name(), destpadname)
+                } else {
+                    format!("{}:*", dest.as_ref().name())
+                },
+                filter,
+            )
+        }
+    }
+
+    fn link_pads_full(
+        &self,
+        srcpadname: Option<&str>,
+        dest: &impl IsA<Element>,
+        destpadname: Option<&str>,
+        flags: crate::PadLinkCheck,
+    ) -> Result<(), glib::error::BoolError> {
+        unsafe {
+            glib::result_from_gboolean!(
+                ffi::gst_element_link_pads_full(
+                    self.as_ref().to_glib_none().0,
+                    srcpadname.to_glib_none().0,
+                    dest.as_ref().to_glib_none().0,
+                    destpadname.to_glib_none().0,
+                    flags.into_glib()
+                ),
+                "Failed to link pads '{}' and '{}' with flags '{:?}'",
+                if let Some(srcpadname) = srcpadname {
+                    format!("{}:{}", self.as_ref().name(), srcpadname)
+                } else {
+                    format!("{}:*", self.as_ref().name())
+                },
+                if let Some(destpadname) = destpadname {
+                    format!("{}:{}", dest.as_ref().name(), destpadname)
+                } else {
+                    format!("{}:*", dest.as_ref().name())
+                },
+                flags,
+            )
+        }
+    }
 }
 
 pub unsafe trait ElementClassExt {