Initialize nowactiveatlower in ratiotest_textbook

[stratakis]

The nowactiveatlower field was only set inside the conditional blocks when a limiting constraint was found (alpha_i < result.alpha). If both loops completed without finding a limiting constraint, the field remained uninitialized.

Uncovered by Coverity static analysis

[stratakis]

Technically this issue won't manifest, as the only caller I found was here:

HiGHS/highs/qpsolver/quass.cpp

Line 478 in 6ab51a3

stepres.nowactiveatlower

Where limitingconstraint != -1 is checked before accessing nowactiveatlower.

However returning a struct with an unitialized field would be considered undefined behaviour.

Full coverity message

``` 1. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:17:3: var_decl: Declaring variable "result" without initializer. 2. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:22:3: path: Condition "j < p.num_nz", taking true branch. 3. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:26:5: path: Condition "alpha_i < result.alpha", taking false branch. 4. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:31:3: path: Jumping back to the beginning of the loop. 5. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:22:3: path: Condition "j < p.num_nz", taking true branch. 6. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:26:5: path: Condition "alpha_i < result.alpha", taking false branch. 7. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:31:3: path: Jumping back to the beginning of the loop. 8. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:22:3: path: Condition "j < p.num_nz", taking false branch. 9. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:34:3: path: Condition "j < rowmove.num_nz", taking true branch. 10. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:39:5: path: Condition "alpha_i < result.alpha", taking false branch. 11. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:44:3: path: Jumping back to the beginning of the loop. 12. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:34:3: path: Condition "j < rowmove.num_nz", taking false branch. 13. scipy-1.16.2/subprojects/highs/src/qpsolver/ratiotest.cpp:46:3: uninit_use: Using uninitialized value "result". Field "result.nowactiveatlower" is uninitialized. # 44| } # 45| # 46|-> return result; # 47| } # 48| ```

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.32%. Comparing base (28f6dc8) to head (55bc415).
⚠️ Report is 6 commits behind head on latest.

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #2778      +/-   ##
==========================================
- Coverage   80.32%   80.32%   -0.01%     
==========================================
  Files         348      348              
  Lines       86073    86093      +20     
==========================================
+ Hits        69142    69152      +10     
- Misses      16931    16941      +10     

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[jajhall]

Thanks for spotting and fixing this