fix(core): validate that begin and end indices of pass timestamp writes are not equal

Author: ErichDonGubler

CHANGELOG.md

@@ -134,6 +134,7 @@ By @ErichDonGubler in [#6456](https://github.com/gfx-rs/wgpu/pull/6456), [#6148]
 - Add missing validation for timestamp writes in compute and render passes (by @ErichDonGubler in [#6578](https://github.com/gfx-rs/wgpu/pull/6578)):
   - Check the status of the `TIMESTAMP_QUERY` feature before other validation.
   - Check that indices are in-bounds for the query set.
+  - Check that begin and end indices are not equal.
 
 #### Naga
 

wgpu-core/src/command/compute.rs

@@ -345,6 +345,15 @@ impl Global {
                 }
             }
 
+            if let Some((begin, end)) = beginning_of_pass_write_index.zip(end_of_pass_write_index) {
+                if begin == end {
+                    return make_err(
+                        CommandEncoderError::TimestampWriteIndicesEqual { idx: begin },
+                        arc_desc,
+                    );
+                }
+            }
+
             Some(ArcPassTimestampWrites {
                 query_set,
                 beginning_of_pass_write_index: tw.beginning_of_pass_write_index,

wgpu-core/src/command/mod.rs

@@ -654,6 +654,10 @@ pub enum CommandEncoderError {
     InvalidResource(#[from] InvalidResourceError),
     #[error(transparent)]
     MissingFeatures(#[from] MissingFeatures),
+    #[error(
+        "begin and end indices of pass timestamp writes are both set to {idx}, which is not allowed"
+    )]
+    TimestampWriteIndicesEqual { idx: u32 },
     #[error(transparent)]
     TimestampWritesInvalid(#[from] QueryUseError),
 }

wgpu-core/src/command/render.rs

@@ -1412,6 +1412,14 @@ impl Global {
                     query_set.validate_query(SimplifiedQueryType::Timestamp, idx, None)?;
                 }
 
+                if let Some((begin, end)) =
+                    beginning_of_pass_write_index.zip(end_of_pass_write_index)
+                {
+                    if begin == end {
+                        return Err(CommandEncoderError::TimestampWriteIndicesEqual { idx: begin });
+                    }
+                }
+
                 Some(ArcPassTimestampWrites {
                     query_set,
                     beginning_of_pass_write_index: tw.beginning_of_pass_write_index,