Further improvements to macos installation tasks

[volpatto]

Fix a Bison frozen installation issue.

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[Copilot]

Pull request overview

This PR addresses a Bison frozen installation issue on macOS by preferring system-installed GNU Bison over PETSc's source build path, which can stall on newer macOS releases. The changes ensure that a modern Bison (≥3.0) is installed via Homebrew and detected before PETSc configuration, preventing long-running or hanging configure processes.

Changes:

• Added automatic installation of bison package on macOS via Homebrew
• Implemented detection and validation of system Bison executables with version checking
• Added graceful fallback for Fortran compiler absence on macOS when ScaLAPACK is requested

[Copilot]

The variable name first_line is misleading because it contains a list of all lines from splitlines(), not just the first line. Consider renaming it to lines for clarity, as in: lines = (probe.stdout or "").splitlines() and version_line = lines[0] if lines else "".

Suggested change

	first_line = (probe.stdout or "").splitlines()
	version_line = first_line[0] if first_line else ""
	lines = (probe.stdout or "").splitlines()
	version_line = lines[0] if lines else ""

[Copilot]

The keyword filtering uses substring matching (any(keyword in f for keyword in ["scalapack", "fortran-bindings"])), which is less precise than the prefix-based matching used earlier in the code (line 680: f.startswith("--with-fortran-bindings=")). While this may work for current PETSc flags, it could inadvertently filter out unrelated flags containing these substrings. Consider using more specific filtering with startswith checks for known flag patterns, similar to the approach used in lines 652-660 for bison flags.

Suggested change

	if not any(keyword in f for keyword in ["scalapack", "fortran-bindings"])
	if not (
	f.startswith("--with-scalapack")
	or f.startswith("--download-scalapack")
	or f.startswith("--with-fortran-bindings=")
	)

[Copilot]

The deduplication approach using dict.fromkeys() differs from the explicit set-based deduplication pattern used consistently elsewhere in this file (see lines 157-162, 216-221, 726-731). For consistency with the established codebase convention, consider using the same pattern:

seen = set()
all_pkgs = []
for pkg in base_pkgs + ["gcc", "bison"]:
    if pkg not in seen:
        all_pkgs.append(pkg)
        seen.add(pkg)

While dict.fromkeys() is functionally correct, using the consistent pattern improves code readability and maintainability.

Suggested change

	all_pkgs = list(dict.fromkeys(base_pkgs + ["gcc", "bison"]))
	seen = set()
	all_pkgs = []
	for pkg in base_pkgs + ["gcc", "bison"]:
	if pkg not in seen:
	all_pkgs.append(pkg)
	seen.add(pkg)

[Copilot]

The regex pattern for parsing GNU Bison version has an awkward structure that may not handle all output formats robustly. The pattern r"GNU Bison\)?\s+(\d+)\.(\d+)" expects an optional closing parenthesis directly after "GNU Bison", which works for "bison (GNU Bison) 3.8.2" by matching "GNU Bison) 3.8", but could fail for variations in formatting. A more robust pattern would be r"[Bb]ison.*?(\d+)\.(\d+)" which matches any line containing "bison" or "Bison" followed by a version number, handling variations like "GNU Bison 3.0", "bison (GNU Bison) 3.8.2", and potential future format changes.

Suggested change

	match = re.search(r"GNU Bison\)?\s+(\d+)\.(\d+)", version_line)
	match = re.search(r"[Bb]ison.*?(\d+)\.(\d+)", version_line)