Merge branch 'latest' into fix-3046

Author: jajhall

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,25 @@
+---
+name: Bug report
+about: Report unexpected behaviour or a crash
+---
+
+Please provide the following information where possible/relevant and check out [CONTRIBUTING.md](https://github.com/ERGO-Code/HiGHS/blob/master/CONTRIBUTING.md).
+
+**What version of HiGHS and what language are you using?**
+Version: master/latest/v1.15.0/v1.14.0 etc.
+Language: C++/C/Python/C#/Fortran/Julia/Rust
+
+**Which solver are you using (e.g. LP, MIP, QP)**
+
+**What operating system (Linux, Windows, ...) and version?**
+
+**What did you do?**
+Steps to reproduce the behaviour:
+
+**What did you expect to see**
+
+**What did you see instead?**
+
+Make sure you include information that can help us debug (full error message, model if possible).
+
+**Anything else we should know about your project / environment**

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Modelling / Usage problem
+    url: https://github.com/ERGO-Code/HiGHS/discussions
+    about: Need help modelling or using HiGHS? Please use Discussions rather than opening an issue.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,18 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+---
+
+Please provide the following information where possible/relevant.
+
+**What language and solver does this apply to?**
+All, C++, C, Python, C#, Fortran / LP, MIP, QP
+
+**Describe the problem you are trying to solve.**
+
+**Describe the solution you'd like**
+
+**Describe alternatives you've considered**
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/pull_request_template.md

@@ -0,0 +1,23 @@
+<!--
+Thank you for contributing to HiGHS!
+
+Please make sure this PR targets the `latest` branch, not `master`.
+-->
+
+## Description
+
+<!-- What does this PR change, and why? -->
+
+## Checklist
+
+- [ ] I have read the [contributing guidelines](https://github.com/ERGO-Code/HiGHS/blob/latest/CONTRIBUTING.md)
+- [ ] This PR targets the `latest` branch
+- [ ] Tests are passing
+- [ ] Documentation was updated where relevant
+- [ ] This PR is not primarily AI-generated (per the AI contributions policy in CONTRIBUTING.md)
+
+<!-- Please uncomment if the PR closes a related issue. -->
+<!--
+## Related issue
+Closes #
+-->

.github/workflows/action-sanitizers-bazel.yml

@@ -58,6 +58,7 @@ jobs:
         run: bazel test -c dbg --config=tsan --runs_per_test 5 //...
 
       - name: Upload bazel-testlogs
+        if: failure()
         uses: actions/upload-artifact@v7
         with:
           name: bazel-testlogs-tsan

CONTRIBUTING.md

@@ -6,26 +6,26 @@ Welcome! This document explains some of the ways you can contribute to HiGHS.
 
 This project and everyone participating in it is governed by the [HiGHS Code of Conduct](https://github.com/ERGO-Code/HiGHS/blob/master/CODE_OF_CONDUCT.md). By participating, you are expected to uphold this code.
 
-## Contact the HiGHS team
+## Contribute code to HiGHS
 
-Contact [Julian](https://github.com/jajhall) (General issues and solvers), [Ivet](https://github.com/galabovaa)  (Build and interfaces)
+HiGHS is open source for distribution rather than contribution. This applies particularly to the core C++ code of the solvers. However, there is definitely scope for external contribution to interfaces and documentation. If you want to contribute in this way, please open an issue before making a pull request, since pull requests to the HiGHS solvers will not normally be accepted.
 
-## Improve the documentation
+Please note that any pull requests to HiGHS must be made to the `latest` branch, so that full testing can take place befor updating `master`. This ensures that `master` is always good to be downloaded by users. As a consequence, any changes should be developed as a branch of `latest` to reduce the chance of merge conflicts.
 
-The top level [documentation](https://ergo-code.github.io/HiGHS/) is created using [Documenter](https://documenter.juliadocs.org/stable/), with the files held on the [HiGHS repository](https://github.com/ERGO-Code/HiGHS/tree/master/docs). If your change is small (like fixing typos, or one or two sentence corrections), the easiest way to do this is to fork the branch and create a pull request. (See *Contribute code to HiGHS* below for more on this.) If your change is larger, or touches multiple files, please raise an issue describing what you want to do.
+Note that, under the terms of the MIT license, by contributing to HiGHS you assign away your rights to the content of your contribution.
 
-## Raise an issue
+## AI generated contributions ##
 
-You can raise an [issue](https://github.com/ERGO-Code/HiGHS/issues) with HiGHS in the normal way via [GitHub](https://docs.github.com/en/issues/tracking-your-work-with-issues/creating-an-issue).
+Whilst AI may be valuable for generating and communicating suggestions for code and build system developments, the review of AI-generated pull requests (other than the most trivial) would require resources that we don't have, so will not be accepted. If the suggestions are good, they will be implemented by HiGHS developers without the use of AI.
 
-## Contribute code to HiGHS
+## Contact the HiGHS team
 
-HiGHS is open source for distribution rather than contribution. This applies particularly to the core C++ code of the solvers. However, there is definitely scope for external contribution to interfaces and documentation. If you want to contribute in this way, please open an issue before making a pull request, since pull requests to the HiGHS solvers will not normally be accepted. 
+Contact [Julian](https://github.com/jajhall) (General issues and solvers), [Ivet](https://github.com/galabovaa)  (Build and interfaces).
 
-Please note that any pull requests to HiGHS must be made to the `latest` branch, so that full testing can take place befor updating `master`. This ensures that `master` is always good to be downloaded by users. As a consequence, any changes should be developed as a branch of `latest` to reduce the chance of merge conflicts.
+## Improve the documentation
 
-Note that, under the terms of the MIT license, by contributing to HiGHS you assign away your rights to the content of your contribution.
+The top level [documentation](https://ergo-code.github.io/HiGHS/) is created using [Documenter](https://documenter.juliadocs.org/stable/), with the files held on the [HiGHS repository](https://github.com/ERGO-Code/HiGHS/tree/master/docs). If your change is small (like fixing typos, or one or two sentence corrections), the easiest way to do this is to fork the branch and create a pull request. (See *Contribute code to HiGHS* for more on this.) If your change is larger, or touches multiple files, please raise an issue describing what you want to do.
 
-## AI generated contributions ##
+## Raise an issue
 
-Whilst AI may be valuable for generating and communicating suggestions for code and build system developments, the review of AI-generated pull requests (other than the most trivial) would require resources that we don't have, so will not be accepted. If the suggestions are good, they will be implemented by HiGHS developers without the use of AI. 
+You can raise an [issue](https://github.com/ERGO-Code/HiGHS/issues) with HiGHS in the normal way via [GitHub](https://docs.github.com/en/issues/tracking-your-work-with-issues/creating-an-issue).

check/Avgas.h

@@ -15,7 +15,7 @@
 
 #include <vector>
 
-#include "util/HighsInt.h"
+#include "util/HighsType.h"
 
 const HighsInt avgas_num_col = 8;
 const HighsInt avgas_num_row = 10;

check/CMakeLists.txt

@@ -81,6 +81,7 @@ if ((NOT FAST_BUILD OR ALL_TESTS) AND NOT (BUILD_EXTRA_UNIT_ONLY))
       TestSetup.cpp
       TestSort.cpp
       TestSpecialLps.cpp
+      TestSymmetry.cpp
       TestThrow.cpp
       TestTspSolver.cpp
       TestUserScale.cpp

check/TestCheckSolution.cpp

@@ -289,7 +289,7 @@ TEST_CASE("check-set-mip-solution", "[highs_check_solution]") {
 
     index.clear();
     value.clear();
-    std::vector<bool> is_set;
+    std::vector<HighsBool> is_set;
     is_set.assign(lp.num_col_, false);
     HighsInt num_to_set = 2;
     assert(num_to_set > 0);

check/TestMipSolver.cpp

@@ -2,6 +2,9 @@
 #include "Highs.h"
 #include "SpecialLps.h"
 #include "catch.hpp"
+#include "mip/HighsCliqueTable.h"
+#include "mip/HighsMipSolver.h"
+#include "mip/HighsMipSolverData.h"
 
 const bool dev_run = false;
 const double double_equal_tolerance = 1e-5;
@@ -1605,3 +1608,99 @@ TEST_CASE("issue-3118a", "[highs_test_mip_solver]") {
 
   highs.resetGlobalScheduler(true);
 }
+
+TEST_CASE("MIP-equality-clique-fixing", "[highs_test_mip_solver]") {
+  // Regression test: when an equality clique has all but one variable fixed,
+  // the last active variable must be fixed before the clique is removed.
+  const HighsInt ncols = 5;
+  HighsLp lp;
+  lp.num_col_ = ncols;
+  lp.num_row_ = 0;
+  lp.col_cost_.assign(ncols, 0.0);
+  lp.col_lower_.assign(ncols, 0.0);
+  lp.col_upper_.assign(ncols, 1.0);
+  lp.integrality_.assign(ncols, HighsVarType::kInteger);
+  lp.a_matrix_.start_.assign(ncols + 1, 0);
+
+  Highs highs;
+  highs.setOptionValue("output_flag", dev_run);
+  highs.passModel(lp);
+
+  HighsCallback callback(&highs);
+  const HighsOptions& options = highs.getOptions();
+  HighsSolution solution;
+  HighsMipSolver mipsolver(callback, options, lp, solution);
+  mipsolver.mipdata_ =
+      std::unique_ptr<HighsMipSolverData>(new HighsMipSolverData(mipsolver));
+  mipsolver.mipdata_->feastol = 1e-6;
+  mipsolver.mipdata_->setupDomainPropagation();
+
+  HighsCliqueTable& cliquetable = mipsolver.mipdata_->cliquetable;
+  HighsDomain& domain = mipsolver.mipdata_->getDomain();
+
+  // Add equality clique: x0 + x1 + x2 + x3 + x4 = 1
+  HighsCliqueTable::CliqueVar clique[] = {
+      {0, 1}, {1, 1}, {2, 1}, {3, 1}, {4, 1}};
+  cliquetable.doAddClique(clique, 5, true);
+  cliquetable.setPresolveFlag(true);
+
+  // Fix x0..x3 = 0 via vertexInfeasible (simulates what cleanupFixed does)
+  for (HighsInt i = 0; i < 4; i++) {
+    domain.fixCol(i, 0.0);
+    cliquetable.vertexInfeasible(domain, i, 1);
+  }
+
+  // The last variable x4 must now be fixed to 1
+  REQUIRE(domain.isFixed(4));
+  REQUIRE(domain.col_lower_[4] == 1.0);
+
+  highs.resetGlobalScheduler(true);
+}
+
+TEST_CASE("MIP-equality-clique-fixing-to-zero", "[highs_test_mip_solver]") {
+  // Same as above but with val=0 clique entries: the active value is 0.
+  // Fixing all but one variable to 1 (inactive) should fix the last to 0.
+  const HighsInt ncols = 5;
+  HighsLp lp;
+  lp.num_col_ = ncols;
+  lp.num_row_ = 0;
+  lp.col_cost_.assign(ncols, 0.0);
+  lp.col_lower_.assign(ncols, 0.0);
+  lp.col_upper_.assign(ncols, 1.0);
+  lp.integrality_.assign(ncols, HighsVarType::kInteger);
+  lp.a_matrix_.start_.assign(ncols + 1, 0);
+
+  Highs highs;
+  highs.setOptionValue("output_flag", dev_run);
+  highs.passModel(lp);
+
+  HighsCallback callback(&highs);
+  const HighsOptions& options = highs.getOptions();
+  HighsSolution solution;
+  HighsMipSolver mipsolver(callback, options, lp, solution);
+  mipsolver.mipdata_ =
+      std::unique_ptr<HighsMipSolverData>(new HighsMipSolverData(mipsolver));
+  mipsolver.mipdata_->feastol = 1e-6;
+  mipsolver.mipdata_->setupDomainPropagation();
+
+  HighsCliqueTable& cliquetable = mipsolver.mipdata_->cliquetable;
+  HighsDomain& domain = mipsolver.mipdata_->getDomain();
+
+  // Add equality clique with val=0: (1-x0) + (1-x1) + ... + (1-x4) = 1
+  HighsCliqueTable::CliqueVar clique[] = {
+      {0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0}};
+  cliquetable.doAddClique(clique, 5, true);
+  cliquetable.setPresolveFlag(true);
+
+  // Fix x0..x3 = 1 via vertexInfeasible (makes their val=0 entry infeasible)
+  for (HighsInt i = 0; i < 4; i++) {
+    domain.fixCol(i, 1.0);
+    cliquetable.vertexInfeasible(domain, i, 0);
+  }
+
+  // The last variable x4 must now be fixed to 0
+  REQUIRE(domain.isFixed(4));
+  REQUIRE(domain.col_upper_[4] == 0.0);
+
+  highs.resetGlobalScheduler(true);
+}