build: capture stderr as output variable

---
type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
report:
  - task: lint_filenames
    status: passed
  - task: lint_editorconfig
    status: passed
  - task: lint_markdown
    status: na
  - task: lint_package_json
    status: na
  - task: lint_repl_help
    status: na
  - task: lint_javascript_src
    status: na
  - task: lint_javascript_cli
    status: na
  - task: lint_javascript_examples
    status: na
  - task: lint_javascript_tests
    status: na
  - task: lint_javascript_benchmarks
    status: na
  - task: lint_python
    status: na
  - task: lint_r
    status: na
  - task: lint_c_src
    status: na
  - task: lint_c_examples
    status: na
  - task: lint_c_benchmarks
    status: na
  - task: lint_c_tests_fixtures
    status: na
  - task: lint_shell
    status: na
  - task: lint_typescript_declarations
    status: na
  - task: lint_typescript_tests
    status: na
  - task: lint_license_headers
    status: passed
---

---
type: pre_push_report
description: Results of running various checks prior to pushing changes.
report:
  - task: run_javascript_examples
    status: na
  - task: run_c_examples
    status: na
  - task: run_cpp_examples
    status: na
  - task: run_javascript_readme_examples
    status: na
  - task: run_c_benchmarks
    status: na
  - task: run_cpp_benchmarks
    status: na
  - task: run_fortran_benchmarks
    status: na
  - task: run_javascript_benchmarks
    status: na
  - task: run_julia_benchmarks
    status: na
  - task: run_python_benchmarks
    status: na
  - task: run_r_benchmarks
    status: na
  - task: run_javascript_tests
    status: na
---

Author: Planeshifter

.github/workflows/lint_random_files.yml

@@ -369,30 +369,41 @@ jobs:
           # Define the path to cppcheck configuration file for linting benchmarks:
           cppcheck_benchmarks_suppressions_list="${root}/etc/cppcheck/suppressions.benchmarks.txt"
 
-          # Lint C source files...
+          # Initialize a variable to capture errors:
+          err_output=""
+
+          # Lint C source files:
           files=$(echo "${{ steps.random-files.outputs.files }}" | tr ',' '\n' | grep -E '\.c$' | grep -v -e '/examples' -e '/test' -e '/benchmark' | tr '\n' ' ')
           if [[ -n "${files}" ]]; then
-            make lint-c-files FILES="${files}"
+            err_output+=$(make lint-c-files FILES="${files}" 2>&1)
           fi
 
           # Lint C example files...
           files=$(echo "${{ steps.random-files.outputs.files }}" | tr ',' '\n' | grep '/examples/.*\.c$' | tr '\n' ' ')
           if [[ -n "${files}" ]]; then
-            make lint-c-files FILES="${files}" CPPCHECK_SUPPRESSIONS_LIST="${cppcheck_examples_suppressions_list}"
+            err_output+=$(make lint-c-files FILES="${files}" CPPCHECK_SUPPRESSIONS_LIST="${cppcheck_examples_suppressions_list}" 2>&1)
           fi
 
           # Lint C test fixtures files...
           files=$(echo "${{ steps.random-files.outputs.files }}" | tr ',' '\n' | grep '/test/fixtures/.*\.c$' | tr '\n' ' ')
           if [[ -n "${files}" ]]; then
-            make lint-c-files FILES="${files}" CPPCHECK_SUPPRESSIONS_LIST="${cppcheck_tests_fixtures_suppressions_list}"
+            err_output+=$(make lint-c-files FILES="${files}" CPPCHECK_SUPPRESSIONS_LIST="${cppcheck_tests_fixtures_suppressions_list}" 2>&1)
           fi
 
           # Lint C benchmark files...
           files=$(echo "${{ steps.random-files.outputs.files }}" | tr ',' '\n' | grep '/benchmark/.*\.c$' | tr '\n' ' ')
           if [[ -n "${files}" ]]; then
-            make lint-c-files FILES="${files}" CPPCHECK_SUPPRESSIONS_LIST="${cppcheck_benchmarks_suppressions_list}"
+            err_output+=$(make lint-c-files FILES="${files}" CPPCHECK_SUPPRESSIONS_LIST="${cppcheck_benchmarks_suppressions_list}" 2>&1)
           fi
 
+          # Print the errors to the log:
+          echo "$err_output"
+
+          # Save the captured errors as an output variable...
+          echo "stderr<<EOF" >> $GITHUB_OUTPUT
+          echo "$err_output" >> $GITHUB_OUTPUT
+          echo "EOF" >> $GITHUB_OUTPUT
+
       # Create sub-issue for C linting failures:
       - name: 'Create sub-issue for C lint failures'
         if: ( github.event.inputs.c != 'false' ) && failure() && contains(steps.*.outcome, 'failure') && contains(steps.lint-c.outcome, 'failure')