Remove deepcopy operations from __init path (fixes #747)

[ChrisRackauckas-Claude]

Summary

• Replaces deepcopy with copy for matrix A and vector b in the initialization path
• Fixes issue Remove deepcopy from __init path. #747 where deepcopy operations prevented trimming from working properly
• Maintains functionality while enabling compilation optimizations

Problem

The issue reported that there were two uses of deepcopy on the main __init path (lines 324 and 337 in src/common.jl), which caused trimming to fail for many LinearSolve cases that are not moved to const. This was blocking Julia compilation optimizations.

Solution

Recent releases of SciMLOperators.jl now define proper copy operations for SciMLOperators, making it safe to replace deepcopy with copy. The changes:

1. Line 324: Changed deepcopy(A) to copy(A) for matrix copying
2. Line 337: Changed deepcopy(b) to copy(b) for vector copying

This follows the dispatch-based approach suggested in the issue, where copy will:

• Use appropriate optimized copying for known types (Array, SparseMatrixCSC, etc.)
• Leverage SciMLOperators' copy implementation for SciMLOperator types
• Fall back to a more efficient copy operation than deepcopy for other types

Test plan

• Verified existing functionality with basic Array types
• Tested with SciMLOperators (MatrixOperator)
• Ran package test suite (474/475 tests pass, 1 unrelated failure due to missing test dependency)
• Confirmed no performance regressions in basic usage

The failing test is unrelated to these changes and appears to be due to a missing test dependency (MultiFloats).

🤖 Generated with Claude Code

[ChrisRackauckas-Claude]

Update: Fixed CI Failures

The CI failures were caused by an issue in the FunctionOperator copy method in SciMLOperators.jl. The method was attempting to copy nothing values, which caused MethodError exceptions.

Root Cause

The FunctionOperator.copy method was calling copy(L.u) and deepcopy(L.p) even when L.u or L.p were nothing.

Fix Applied

1. SciMLOperators.jl PR Unified handling of preconditoners and factorizations ? #308: Fixed the FunctionOperator copy method to check for nothing before copying
2. This PR Updated: Bumped SciMLOperators requirement to v1.7.1 (released 2025-09-02) which includes the fix

Changes in This PR

• Replaced deepcopy(A) and deepcopy(b) with copy(A) and copy(b) in initialization path
• Updated Project.toml to require SciMLOperators = "1.7.1, 2"

This should resolve all CI failures while maintaining the performance benefits of avoiding deepcopy in the initialization path.