Do not error when trying to convert corrupted compiler entries (#49759)

fixes #49717

If no compiler is listed in the 'packages' section of
the configuration, Spack will currently try to:
1. Look for a legacy compilers.yaml to convert
2. Look for compilers in PATH

in that order. If an entry in compilers.yaml is
corrupted, that should not result in an obscure
error.

Instead, it should just be skipped.

Signed-off-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>

lib/spack/spack/compilers/config.py

@@ -7,6 +7,7 @@
 import os
 import re
 import sys
+import warnings
 from typing import Any, Dict, List, Optional, Tuple
 
 import archspec.cpu
@@ -337,7 +338,15 @@ def from_legacy_yaml(compiler_dict: Dict[str, Any]) -> List[spack.spec.Spec]:
             pkg_cls = spack.repo.PATH.get_pkg_class(pkg_name)
             pattern = re.compile(r"|".join(finder.search_patterns(pkg=pkg_cls)))
             filtered_paths = [x for x in candidate_paths if pattern.search(os.path.basename(x))]
+            try:
                 detected = finder.detect_specs(pkg=pkg_cls, paths=filtered_paths)
+            except Exception:
+                warnings.warn(
+                    f"[{__name__}] cannot detect {pkg_name} from the "
+                    f"following paths: {', '.join(filtered_paths)}"
+                )
+                continue
+
             for s in detected:
                 for key in ("flags", "environment", "extra_rpaths"):
                     if key in compiler_dict:

lib/spack/spack/test/compilers/conversion.py

@@ -83,3 +83,12 @@ def tests_compiler_conversion_modules(mock_compiler):
     compiler_spec = CompilerFactory.from_legacy_yaml(mock_compiler)[0]
     assert compiler_spec.external
     assert compiler_spec.external_modules == modules
+
+
+@pytest.mark.regression("49717")
+def tests_compiler_conversion_corrupted_paths(mock_compiler):
+    """Tests that compiler entries with corrupted path do not raise"""
+    mock_compiler["paths"] = {"cc": "gcc", "cxx": "g++", "fc": "gfortran", "f77": "gfortran"}
+    # Test this call doesn't raise
+    compiler_spec = CompilerFactory.from_legacy_yaml(mock_compiler)
+    assert compiler_spec == []