gstreamer: use thiserror crate

Make code simpler and fix deprecated warning when building on nightly as
Error::description is being deprecated.

gstreamer/Cargo.toml

@@ -29,6 +29,7 @@ serde_bytes = { version = "0.11", optional = true }
 serde_derive = { version = "1.0", optional = true }
 paste = { version = "0.1" }
 pretty-hex = "0.1"
+thiserror = "1"
 
 [build-dependencies]
 rustdoc-stripper = { version = "0.1", optional = true }

gstreamer/src/enums.rs

@@ -6,9 +6,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::error::Error;
-use std::fmt;
 use std::{cmp, ops};
+use thiserror::Error;
 use ClockReturn;
 use FlowReturn;
 use PadLinkReturn;
@@ -59,28 +58,17 @@ impl From<StateChangeSuccess> for StateChangeReturn {
     }
 }
 
-#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Error)]
 #[must_use]
+#[error("Element failed to change its state")]
 pub struct StateChangeError;
 
-impl fmt::Display for StateChangeError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "State-change error")
-    }
-}
-
 impl From<StateChangeError> for StateChangeReturn {
     fn from(value: StateChangeError) -> Self {
         StateChangeReturn::from_error(value)
     }
 }
 
-impl Error for StateChangeError {
-    fn description(&self) -> &str {
-        "Element failed to change its state"
-    }
-}
-
 impl From<Result<StateChangeSuccess, StateChangeError>> for StateChangeReturn {
     fn from(res: Result<StateChangeSuccess, StateChangeError>) -> Self {
         match res {
@@ -155,52 +143,35 @@ impl From<FlowSuccess> for FlowReturn {
     }
 }
 
-#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Error)]
 #[must_use]
 pub enum FlowError {
+    #[error("Pad is not linked")]
     NotLinked,
+    #[error("Pad is flushing")]
     Flushing,
+    #[error("Pad is EOS")]
     Eos,
+    #[error("Pad is not negotiated")]
     NotNegotiated,
+    #[error("Some (fatal) error occurred. Element generating this error should post an error message with more details")]
     Error,
+    #[error("This operation is not supported")]
     NotSupported,
+    #[error("Elements can use values starting from this (and lower) to define custom error codes")]
     CustomError,
+    #[error("Pre-defined custom error code")]
     CustomError1,
+    #[error("Pre-defined custom error code")]
     CustomError2,
 }
 
-impl fmt::Display for FlowError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "Flow error: {}", self.description())
-    }
-}
-
 impl From<FlowError> for FlowReturn {
     fn from(value: FlowError) -> Self {
         FlowReturn::from_error(value)
     }
 }
 
-impl Error for FlowError {
-    fn description(&self) -> &str {
-        match *self {
-            FlowError::NotLinked => "Pad is not linked",
-            FlowError::Flushing => "Pad is flushing",
-            FlowError::Eos => "Pad is EOS",
-            FlowError::NotNegotiated => "Pad is not negotiated",
-            FlowError::Error => {
-                "Some (fatal) error occurred. Element generating this error should post an error message with more details"
-            }
-            FlowError::NotSupported => "This operation is not supported",
-            FlowError::CustomError => {
-                "Elements can use values starting from this (and lower) to define custom error codes"
-            }
-            FlowError::CustomError1 => "Pre-defined custom error code",
-            FlowError::CustomError2 => "Pre-defined custom error code",
-        }
-    }
-}
-
 impl From<Result<FlowSuccess, FlowError>> for FlowReturn {
     fn from(res: Result<FlowSuccess, FlowError>) -> Self {
         match res {
@@ -249,42 +220,29 @@ impl From<PadLinkSuccess> for PadLinkReturn {
     }
 }
 
-#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Error)]
 #[must_use]
 pub enum PadLinkError {
+    #[error("Pads have no common grandparent")]
     WrongHierarchy,
+    #[error("Pad was already linked")]
     WasLinked,
+    #[error("Pads have wrong direction")]
     WrongDirection,
+    #[error("Pads do not have common format")]
     Noformat,
+    #[error("Pads cannot cooperate in scheduling")]
     Nosched,
+    #[error("Refused for some other reason")]
     Refused,
 }
 
-impl fmt::Display for PadLinkError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "Pad failed to link: {}", self.description())
-    }
-}
-
 impl From<PadLinkError> for PadLinkReturn {
     fn from(value: PadLinkError) -> Self {
         PadLinkReturn::from_error(value)
     }
 }
 
-impl Error for PadLinkError {
-    fn description(&self) -> &str {
-        match *self {
-            PadLinkError::WrongHierarchy => "Pads have no common grandparent",
-            PadLinkError::WasLinked => "Pad was already linked",
-            PadLinkError::WrongDirection => "Pads have wrong direction",
-            PadLinkError::Noformat => "Pads do not have common format",
-            PadLinkError::Nosched => "Pads cannot cooperate in scheduling",
-            PadLinkError::Refused => "Refused for some other reason",
-        }
-    }
-}
-
 impl From<Result<PadLinkSuccess, PadLinkError>> for PadLinkReturn {
     fn from(res: Result<PadLinkSuccess, PadLinkError>) -> Self {
         match res {
@@ -340,42 +298,29 @@ impl From<ClockSuccess> for ClockReturn {
     }
 }
 
-#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Error)]
 #[must_use]
 pub enum ClockError {
+    #[error("The operation was scheduled too late")]
     Early,
+    #[error("The clockID was unscheduled")]
     Unscheduled,
+    #[error("The ClockID is busy")]
     Busy,
+    #[error("A bad time was provided to a function")]
     Badtime,
+    #[error("An error occurred")]
     Error,
+    #[error("Operation is not supported")]
     Unsupported,
 }
 
-impl fmt::Display for ClockError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "Clock error: {}", self.description())
-    }
-}
-
 impl From<ClockError> for ClockReturn {
     fn from(value: ClockError) -> Self {
         ClockReturn::from_error(value)
     }
 }
 
-impl Error for ClockError {
-    fn description(&self) -> &str {
-        match *self {
-            ClockError::Early => "The operation was scheduled too late",
-            ClockError::Unscheduled => "The clockID was unscheduled",
-            ClockError::Busy => "The ClockID is busy",
-            ClockError::Badtime => "A bad time was provided to a function",
-            ClockError::Error => "An error occurred",
-            ClockError::Unsupported => "Operation is not supported",
-        }
-    }
-}
-
 impl From<Result<ClockSuccess, ClockError>> for ClockReturn {
     fn from(res: Result<ClockSuccess, ClockError>) -> Self {
         match res {
@@ -489,26 +434,13 @@ impl ops::SubAssign<u32> for ::Rank {
     }
 }
 
-#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Error)]
 #[must_use]
 pub enum TagError {
+    #[error("The value type doesn't match with the specified Tag")]
     TypeMismatch,
 }
 
-impl fmt::Display for TagError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "Tag error: {}", self.description())
-    }
-}
-
-impl Error for TagError {
-    fn description(&self) -> &str {
-        match *self {
-            TagError::TypeMismatch => "The value type doesn't match with the specified Tag",
-        }
-    }
-}
-
 // This cannot be done automatically because in GStreamer it's exposed as a bitflag but works as an
 // enum instead
 #[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)]

gstreamer/src/error.rs

@@ -6,8 +6,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::error::Error;
+use thiserror::Error;
-use std::fmt;
 
 use glib;
 use glib::IsA;
@@ -50,7 +49,8 @@ macro_rules! gst_error_msg(
     }};
 );
 
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Error)]
+#[error("Error {:?} ({:?}) at {}:{}", .message, .debug, .filename, .line)]
 pub struct ErrorMessage {
     pub(crate) error_domain: glib::Quark,
     pub(crate) error_code: i32,
@@ -85,22 +85,6 @@ impl ErrorMessage {
     }
 }
 
-impl fmt::Display for ErrorMessage {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        write!(
-            f,
-            "Error {:?} ({:?}) at {}:{}",
-            self.message, self.debug, self.filename, self.line
-        )
-    }
-}
-
-impl Error for ErrorMessage {
-    fn description(&self) -> &str {
-        "ErrorMessage"
-    }
-}
-
 #[macro_export]
 macro_rules! gst_loggable_error(
 // Plain strings
@@ -129,7 +113,8 @@ macro_rules! gst_result_from_gboolean(
     }};
 );
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Error)]
+#[error("Error {:?}: {:?} at {}:{}", .category.get_name(), .bool_error.message, .bool_error.filename, .bool_error.line)]
 pub struct LoggableError {
     category: ::DebugCategory,
     bool_error: glib::BoolError,
@@ -179,25 +164,6 @@ impl From<glib::BoolError> for LoggableError {
     }
 }
 
-impl fmt::Display for LoggableError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        write!(
-            f,
-            "Error {:?}: {:?} at {}:{}",
-            self.category.get_name(),
-            self.bool_error.message,
-            self.bool_error.filename,
-            self.bool_error.line
-        )
-    }
-}
-
-impl Error for LoggableError {
-    fn description(&self) -> &str {
-        self.bool_error.message.as_ref()
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

gstreamer/src/iterator.rs

@@ -15,7 +15,6 @@ use glib_sys;
 use glib_sys::{gconstpointer, gpointer};
 use gobject_sys;
 use gst_sys;
-use std::error::Error;
 use std::ffi::CString;
 use std::fmt;
 use std::iter;
@@ -23,31 +22,16 @@ use std::marker::PhantomData;
 use std::mem;
 use std::ptr;
 use std::sync::Arc;
+use thiserror::Error;
 
-#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Error)]
 pub enum IteratorError {
+    #[error("Resync")]
     Resync,
+    #[error("Error")]
     Error,
 }
 
-impl fmt::Display for IteratorError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match *self {
-            IteratorError::Resync => write!(f, "Resync"),
-            IteratorError::Error => write!(f, "Error"),
-        }
-    }
-}
-
-impl Error for IteratorError {
-    fn description(&self) -> &str {
-        match *self {
-            IteratorError::Resync => "Resync",
-            IteratorError::Error => "Error",
-        }
-    }
-}
-
 // Implemented manually so that we can use generics for the item
 pub struct Iterator<T> {
     iter: ptr::NonNull<gst_sys::GstIterator>,

gstreamer/src/lib.rs

@@ -15,6 +15,7 @@ extern crate cfg_if;
 #[macro_use]
 extern crate lazy_static;
 extern crate libc;
+extern crate thiserror;
 
 // Re-exported for the subclass gst_plugin_define! macro
 #[doc(hidden)]

gstreamer/src/subclass/error.rs

@@ -6,9 +6,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::error::Error;
+use thiserror::Error;
-use std::fmt::Error as FmtError;
-use std::fmt::{Display, Formatter};
 
 use ErrorMessage;
 use FlowReturn;
@@ -47,11 +45,15 @@ macro_rules! gst_panic_to_error(
     }};
 );
 
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Error)]
 pub enum FlowError {
+    #[error("Flushing")]
     Flushing,
+    #[error("Eos")]
     Eos,
+    #[error("Not Negotiated")]
     NotNegotiated(ErrorMessage),
+    #[error("Error")]
     Error(ErrorMessage),
 }
 
@@ -71,26 +73,3 @@ impl<'a> From<&'a FlowError> for FlowReturn {
         }
     }
 }
-
-impl Display for FlowError {
-    fn fmt(&self, f: &mut Formatter) -> Result<(), FmtError> {
-        match *self {
-            FlowError::Flushing | FlowError::Eos => f.write_str(self.description()),
-            FlowError::NotNegotiated(ref m) => {
-                f.write_fmt(format_args!("{}: {}", self.description(), m))
-            }
-            FlowError::Error(ref m) => f.write_fmt(format_args!("{}: {}", self.description(), m)),
-        }
-    }
-}
-
-impl Error for FlowError {
-    fn description(&self) -> &str {
-        match *self {
-            FlowError::Flushing => "Flushing",
-            FlowError::Eos => "Eos",
-            FlowError::NotNegotiated(..) => "Not Negotiated",
-            FlowError::Error(..) => "Error",
-        }
-    }
-}