Move NoLibrariesError/NoHeadersError into error.py (#10997)

Also add constructor to NoLibrariesError which can either take an
error message (like other SpackErrors) or a name and prefix (in
which case the error message is constructed).

lib/spack/spack/build_environment.py

@@ -58,6 +58,7 @@
     env_flag, filter_system_paths, get_path, is_system_path,
     EnvironmentModifications, validate, preserve_environment)
 from spack.util.environment import system_dirs
+from spack.error import NoLibrariesError, NoHeadersError
 from spack.util.executable import Executable
 from spack.util.module_cmd import load_module, get_path_from_module
 from spack.util.log_parse import parse_log_events, make_log_context
@@ -280,7 +281,7 @@ def set_build_environment_variables(pkg, env, dirty):
         dep_link_dirs = list()
         try:
             dep_link_dirs.extend(query.libs.directories)
-        except spack.spec.NoLibrariesError:
+        except NoLibrariesError:
             tty.debug("No libraries found for {0}".format(dep.name))
 
         for default_lib_dir in ['lib', 'lib64']:
@@ -294,7 +295,7 @@ def set_build_environment_variables(pkg, env, dirty):
 
         try:
             include_dirs.extend(query.headers.directories)
-        except spack.spec.NoHeadersError:
+        except NoHeadersError:
             tty.debug("No headers found for {0}".format(dep.name))
 
     link_dirs = list(dedupe(filter_system_paths(link_dirs)))

lib/spack/spack/error.py

@@ -98,6 +98,21 @@ def __init__(self, message):
         super(UnsupportedPlatformError, self).__init__(message)
 
 
+class NoLibrariesError(SpackError):
+    """Raised when package libraries are requested but cannot be found"""
+
+    def __init__(self, message_or_name, prefix=None):
+        super(NoLibrariesError, self).__init__(
+            message_or_name if prefix is None else
+            'Unable to locate {0} libraries in {1}'.format(
+                message_or_name, prefix)
+        )
+
+
+class NoHeadersError(SpackError):
+    """Raised when package headers are requested but cannot be found"""
+
+
 class SpecError(SpackError):
     """Superclass for all errors that occur while constructing specs."""
 

lib/spack/spack/spec.py

@@ -109,7 +109,8 @@
 
 from spack.dependency import Dependency, all_deptypes, canonical_deptype
 from spack.util.module_cmd import get_path_from_module, load_module
-from spack.error import SpackError, SpecError, UnsatisfiableSpecError
+from spack.error import NoLibrariesError, NoHeadersError
+from spack.error import SpecError, UnsatisfiableSpecError
 from spack.provider_index import ProviderIndex
 from spack.util.crypto import prefix_bits
 from spack.util.executable import Executable
@@ -4019,14 +4020,6 @@ class DuplicateCompilerSpecError(SpecError):
     """Raised when the same compiler occurs in a spec twice."""
 
 
-class NoLibrariesError(SpackError):
-    """Raised when package libraries are requested but cannot be found"""
-
-
-class NoHeadersError(SpackError):
-    """Raised when package headers are requested but cannot be found"""
-
-
 class UnsupportedCompilerError(SpecError):
     """Raised when the user asks for a compiler spack doesn't know about."""
     def __init__(self, compiler_name):