[Sylvester Kaczmarek (sylvesterkaczmarek)]

Description

Fixes #32405.

FuseInitializersTransformer locates the consumer input to replace by comparing the producer node name with consumer input value names. ONNX does not require node names and output value names to match.

When they differ, the lookup can reach the end of InputDefs() and the following access can go out of bounds.

The transformer now matches the consumer input against the Cast node's output value name and guards against an unexpected missing match.

Tests

Adds a regression test where the Cast node name differs from its output value name, matching the failure reported in #32405.

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[Copilot]

🟢 Approval recommended

The focused fix addresses the reported crash and includes adequate regression coverage.

Pull request overview

Fixes initializer fusion when Cast node and output names differ, preventing out-of-bounds access.

Changes:

• Match consumer inputs using the Cast output value name.
• Enforce that a matching consumer input exists.
• Add regression coverage for independently named nodes and values.

File summaries

File	Description
onnxruntime/core/optimizer/fuse_initializers_transformer.cc	Corrects consumer input lookup and adds a bounds guard.
onnxruntime/test/optimizer/fuse_initializers_transformer_regression_test.cc	Verifies successful fusion with differing Cast node/output names.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Balanced

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