_project.py: Add fatal-warnings configuration item

This allows for users to configure fatal-warnings to be either a list of
warnings.

This commit deprecates the use of fail-on-overlap within project.conf,
this will now use the fatal-warnings configuration item.

element.py: Cache key calculation now takes into account all of the
fatal-warnings

tests: This modifys the tests/frontend/overlaps.py tests to support the
new fatal-warnings configuration. Backwards compatibility is also
tested for `fail-on-overlap`

_versions.py: BST_FORMAT_VERSION bumped to 16 for fatal-warnings
	      BST_CORE_ARTIFACT_VERSION bumpted to 5 for fatal-warnings

Fixes: #526

32 files changed, 151 insertions, 67 deletions

diff --git a/buildstream/_project.py b/buildstream/_project.py
index 1660c4770..6e4f09c68 100644
--- a/buildstream/_project.py
+++ b/buildstream/_project.py
@@ -31,6 +31,7 @@ from ._options import OptionPool
 from ._artifactcache import ArtifactCache
 from ._elementfactory import ElementFactory
 from ._sourcefactory import SourceFactory
+from .plugin import CoreWarnings
 from ._projectrefs import ProjectRefs, ProjectRefStorage
 from ._versions import BST_FORMAT_VERSION
 from ._loader import Loader
@@ -105,7 +106,7 @@ class Project():
         self.first_pass_config = ProjectConfig()
 
         self.junction = junction                 # The junction Element object, if this is a subproject
-        self.fail_on_overlap = False             # Whether overlaps are treated as errors
+
         self.ref_storage = None                  # ProjectRefStorage setting
         self.base_environment = {}               # The base set of environment variables
         self.base_env_nocache = None             # The base nocache mask (list) for the environment
@@ -120,6 +121,8 @@ class Project():
         self._cli_options = cli_options
         self._cache_key = None
 
+        self._fatal_warnings = []             # A list of warnings which should trigger an error
+
         self._shell_command = []      # The default interactive shell command
         self._shell_environment = {}  # Statically set environment vars
         self._shell_host_files = []   # A list of HostMount objects
@@ -470,7 +473,7 @@ class Project():
             'split-rules', 'elements', 'plugins',
             'aliases', 'name',
             'artifacts', 'options',
-            'fail-on-overlap', 'shell',
+            'fail-on-overlap', 'shell', 'fatal-warnings',
             'ref-storage', 'sandbox', 'mirrors'
         ])
 
@@ -492,8 +495,25 @@ class Project():
         # Load project split rules
         self._splits = _yaml.node_get(config, Mapping, 'split-rules')
 
-        # Fail on overlap
-        self.fail_on_overlap = _yaml.node_get(config, bool, 'fail-on-overlap')
+        # Fatal warnings
+        self._fatal_warnings = _yaml.node_get(config, list, 'fatal-warnings', default_value=[])
+
+        # Support backwards compatibility for fail-on-overlap
+        fail_on_overlap = _yaml.node_get(config, bool, 'fail-on-overlap', default_value=None)
+
+        if (CoreWarnings.OVERLAPS not in self._fatal_warnings) and fail_on_overlap:
+            self._fatal_warnings.append(CoreWarnings.OVERLAPS)
+
+        # Deprecation check
+        if fail_on_overlap is not None:
+            self._context.message(
+                Message(
+                    None,
+                    MessageType.WARN,
+                    "Use of fail-on-overlap within project.conf " +
+                    "is deprecated. Consider using fatal-warnings instead."
+                )
+            )
 
         # Load project.refs if it exists, this may be ignored.
         if self.ref_storage == ProjectRefStorage.PROJECT_REFS:
@@ -734,3 +754,17 @@ class Project():
                 # paths are passed in relative to the project, but must be absolute
                 origin_dict['path'] = os.path.join(self.directory, path)
             destination.append(origin_dict)
+
+    # _warning_is_fatal():
+    #
+    # Returns true if the warning in question should be considered fatal based on
+    # the project configuration.
+    #
+    # Args:
+    #   warning_str (str): The warning configuration string to check against
+    #
+    # Returns:
+    #    (bool): True if the warning should be considered fatal and cause an error.
+    #
+    def _warning_is_fatal(self, warning_str):
+        return warning_str in self._fatal_warnings
diff --git a/buildstream/_versions.py b/buildstream/_versions.py
index e0ec4cdec..e4d503929 100644
--- a/buildstream/_versions.py
+++ b/buildstream/_versions.py
@@ -23,7 +23,7 @@
 # This version is bumped whenever enhancements are made
 # to the `project.conf` format or the core element format.
 #
-BST_FORMAT_VERSION = 15
+BST_FORMAT_VERSION = 16
 
 
 # The base BuildStream artifact version
@@ -34,4 +34,4 @@ BST_FORMAT_VERSION = 15
 # the same cache key to produce something that is no longer
 # the same.
 
-BST_CORE_ARTIFACT_VERSION = ('bst-1.2', 3)
+BST_CORE_ARTIFACT_VERSION = ('bst-1.2', 4)
diff --git a/buildstream/data/projectconfig.yaml b/buildstream/data/projectconfig.yaml
index 247a4536a..eca6e57ad 100644
--- a/buildstream/data/projectconfig.yaml
+++ b/buildstream/data/projectconfig.yaml
@@ -13,10 +13,6 @@ element-path: .
 # Store source references in element files
 ref-storage: inline
 
-# Overlaps are just warnings
-fail-on-overlap: False
-
-
 # Variable Configuration
 #
 variables:
diff --git a/buildstream/element.py b/buildstream/element.py
index 2fc56d947..370eb7547 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -96,6 +96,7 @@ from . import _cachekey
 from . import _signals
 from . import _site
 from ._platform import Platform
+from .plugin import CoreWarnings
 from .sandbox._config import SandboxConfig
 
 
@@ -768,31 +769,23 @@ class Element(Plugin):
                 ignored[dep.name] = result.ignored
 
         if overlaps:
-            overlap_error = overlap_warning = False
-            error_detail = warning_detail = "Staged files overwrite existing files in staging area:\n"
+            overlap_warning = False
+            warning_detail = "Staged files overwrite existing files in staging area:\n"
             for f, elements in overlaps.items():
-                overlap_error_elements = []
                 overlap_warning_elements = []
                 # The bottom item overlaps nothing
                 overlapping_elements = elements[1:]
                 for elm in overlapping_elements:
                     element = self.search(scope, elm)
                     if not element.__file_is_whitelisted(f):
-                        if project.fail_on_overlap:
-                            overlap_error_elements.append(elm)
-                            overlap_error = True
-                        else:
-                            overlap_warning_elements.append(elm)
-                            overlap_warning = True
+                        overlap_warning_elements.append(elm)
+                        overlap_warning = True
 
                 warning_detail += _overlap_error_detail(f, overlap_warning_elements, elements)
-                error_detail += _overlap_error_detail(f, overlap_error_elements, elements)
 
             if overlap_warning:
-                self.warn("Non-whitelisted overlaps detected", detail=warning_detail)
-            if overlap_error:
-                raise ElementError("Non-whitelisted overlaps detected and fail-on-overlaps is set",
-                                   detail=error_detail, reason="overlap-error")
+                self.warn("Non-whitelisted overlaps detected", detail=warning_detail,
+                          warning_token=CoreWarnings.OVERLAPS)
 
         if ignored:
             detail = "Not staging files which would replace non-empty directories:\n"
@@ -2012,9 +2005,7 @@ class Element(Plugin):
                 'cache': type(self.__artifacts).__name__
             }
 
-            # fail-on-overlap setting cannot affect elements without dependencies
-            if project.fail_on_overlap and dependencies:
-                self.__cache_key_dict['fail-on-overlap'] = True
+            self.__cache_key_dict['fatal-warnings'] = sorted(project._fatal_warnings)
 
         cache_key_dict = self.__cache_key_dict.copy()
         cache_key_dict['dependencies'] = dependencies
diff --git a/buildstream/plugin.py b/buildstream/plugin.py
index fbcf249bb..a60b501eb 100644
--- a/buildstream/plugin.py
+++ b/buildstream/plugin.py
@@ -206,7 +206,6 @@ class Plugin():
         # Infer the kind identifier
         modulename = type(self).__module__
         self.__kind = modulename.split('.')[-1]
-
         self.debug("Created: {}".format(self))
 
     def __del__(self):
@@ -513,14 +512,28 @@ class Plugin():
         """
         self.__message(MessageType.INFO, brief, detail=detail)
 
-    def warn(self, brief, *, detail=None):
-        """Print a warning message
+    def warn(self, brief, *, detail=None, warning_token=None):
+        """Print a warning message, checks warning_token against project configuration
 
         Args:
            brief (str): The brief message
            detail (str): An optional detailed message, can be multiline output
+           warning_token (str): An optional configurable warning assosciated with this warning,
+                                this will cause PluginError to be raised if this warning is configured as fatal.
+                                (*Since 1.4*)
+
+        Raises:
+           (:class:`.PluginError`): When warning_token is considered fatal by the project configuration
         """
-        self.__message(MessageType.WARN, brief, detail=detail)
+        if warning_token:
+            warning_token = _prefix_warning(self, warning_token)
+            brief = "[{}]: {}".format(warning_token, brief)
+            project = self._get_project()
+
+            if project._warning_is_fatal(warning_token):
+                raise PluginError(message="{}\n{}".format(brief, detail), reason=warning_token)
+
+        self.__message(MessageType.WARN, brief=brief, detail=detail)
 
     def log(self, brief, *, detail=None):
         """Log a message into the plugin's log file
@@ -784,3 +797,46 @@ class Plugin():
             return '{}:{}'.format(project.junction.name, self.name)
         else:
             return self.name
+
+
+class CoreWarnings():
+    """CoreWarnings()
+
+    Some common warnings which are raised by core functionalities within BuildStream are found in this class.
+    """
+
+    OVERLAPS = "overlaps"
+    """
+    This warning will be produced when buildstream detects an overlap on an element
+        which is not whitelisted.
+    """
+
+    REF_NOT_IN_TRACK = "ref-not-in-track"
+    """
+    This warning will be produced when a source is configured with a reference
+    which is found to be invalid based on the configured track
+    """
+
+
+__CORE_WARNINGS = [
+    value
+    for name, value in CoreWarnings.__dict__.items()
+    if not name.startswith("__")
+]
+
+
+# _prefix_warning():
+#
+# Prefix a warning with the plugin kind. CoreWarnings are not prefixed.
+#
+# Args:
+#   plugin (Plugin): The plugin which raised the warning
+#   warning (str): The warning to prefix
+#
+# Returns:
+#    (str): A prefixed warning
+#
+def _prefix_warning(plugin, warning):
+    if any((warning is core_warning for core_warning in __CORE_WARNINGS)):
+        return warning
+    return "{}:{}".format(plugin.get_kind(), warning)
diff --git a/tests/cachekey/project/elements/build1.expected b/tests/cachekey/project/elements/build1.expected
index 750d06234..70d29bffd 100644
--- a/tests/cachekey/project/elements/build1.expected
+++ b/tests/cachekey/project/elements/build1.expected
@@ -1 +1 @@
-afab4c1a67d1e06489083fa1559bda0b2c8df9b7bc239820ed7cdab30c988a4e
\ No newline at end of file
+9195e7c5f1326b878275c3953e39f87fa9909b9eecfe1b07cb23dcbf61e52a70
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/build2.expected b/tests/cachekey/project/elements/build2.expected
index 3b40d2ddf..2401ea01a 100644
--- a/tests/cachekey/project/elements/build2.expected
+++ b/tests/cachekey/project/elements/build2.expected
@@ -1 +1 @@
-47395a4e6c86372b181ad1fd6443e11b1ab54c480b7be5e5fe816d84eec3b369
\ No newline at end of file
+beb17868e92bdf5203d6a9263cffc91c3252f329116afc04855fe8ef529d77c4
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/compose1.expected b/tests/cachekey/project/elements/compose1.expected
index 7289d9919..71c199104 100644
--- a/tests/cachekey/project/elements/compose1.expected
+++ b/tests/cachekey/project/elements/compose1.expected
@@ -1 +1 @@
-f8b69ac5ce84a8e8db30f9ae58d7560054d41da311176f74047694ec1203d7e8
\ No newline at end of file
+ef47f8a74e6c96f3d8386ee9b4e4999b91e3fa44a063ee480505c4ae3b9af55a
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/compose2.expected b/tests/cachekey/project/elements/compose2.expected
index f80f6fb1e..08af0b347 100644
--- a/tests/cachekey/project/elements/compose2.expected
+++ b/tests/cachekey/project/elements/compose2.expected
@@ -1 +1 @@
-4f542af0ebf3136b0affe42cb5574b7cf1034db6fb60d272ab2304e1c99b0d6f
\ No newline at end of file
+739450b3cd7b6cd870ef136ef94880f824f381834b1d5a8c7f616a6590eb34ef
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/compose3.expected b/tests/cachekey/project/elements/compose3.expected
index 7b9d23ed4..e77e7af48 100644
--- a/tests/cachekey/project/elements/compose3.expected
+++ b/tests/cachekey/project/elements/compose3.expected
@@ -1 +1 @@
-93863a5513f3b59a107a3ba23a6e47b38738e7c99ac462d2379308dab9910d8f
\ No newline at end of file
+c250ea677c5be87114ae1199ebd3ee5f0ceefc6e417b09c8be94448a942a15ac
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/compose4.expected b/tests/cachekey/project/elements/compose4.expected
index 7feb88917..d656e6e20 100644
--- a/tests/cachekey/project/elements/compose4.expected
+++ b/tests/cachekey/project/elements/compose4.expected
@@ -1 +1 @@
-e66827c4f0beffbb9eff52522539b10945ad108bd5ad722107e5dfbce7d064ef
\ No newline at end of file
+729f40643a6b14b08ed70108ccd9efeb2024ccf4fcd7102996857bc4a75c8eb7
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/compose5.expected b/tests/cachekey/project/elements/compose5.expected
index d99aa675f..d9c69186a 100644
--- a/tests/cachekey/project/elements/compose5.expected
+++ b/tests/cachekey/project/elements/compose5.expected
@@ -1 +1 @@
-74a1fcb3c1c7829962398cc104a30d52aeb38af9fe8631a6b77112a1fe99b653
\ No newline at end of file
+7e59a1292236d81ac1b79d5d8f188c1457488608944842e45b0c2f813bf08fee
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/import1.expected b/tests/cachekey/project/elements/import1.expected
index b9020e2d0..fdb2911e5 100644
--- a/tests/cachekey/project/elements/import1.expected
+++ b/tests/cachekey/project/elements/import1.expected
@@ -1 +1 @@
-619692c94c9b499eaa23358b45fd75b4526d9f5b6d3a6061faad9b6726510db3
\ No newline at end of file
+92a12959aba0d4123f383e8d285e1989877f04074d248b3d5bae801d14801fa0
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/import2.expected b/tests/cachekey/project/elements/import2.expected
index 27a365a64..c7c325048 100644
--- a/tests/cachekey/project/elements/import2.expected
+++ b/tests/cachekey/project/elements/import2.expected
@@ -1 +1 @@
-8e1ee1f99738be5162e97194d9aa72aef0a9d3458218747f9721102f2d7104d7
\ No newline at end of file
+f3d07c82b0bea080dc1783a07234910129cc4f95edab6868482395d77503e445
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/import3.expected b/tests/cachekey/project/elements/import3.expected
index 8e8eed096..4b943859d 100644
--- a/tests/cachekey/project/elements/import3.expected
+++ b/tests/cachekey/project/elements/import3.expected
@@ -1 +1 @@
-5d9cfb59d10bb98ca17c52cf8862b84a39202b1d83074a8b8dd3da83a0303c19
\ No newline at end of file
+647fe25d06131191ff1b2898f6c57f88f206f6e11297fa25f30610b77fc22e6e
\ No newline at end of file
diff --git a/tests/cachekey/project/elements/script1.expected b/tests/cachekey/project/elements/script1.expected
index 3613c35d7..f7951113c 100644
--- a/tests/cachekey/project/elements/script1.expected
+++ b/tests/cachekey/project/elements/script1.expected
@@ -1 +1 @@
-7df04616b29ee538ec5e290dcfd7fdfce9cacdbaf224597856272aec3939d5c8
\ No newline at end of file
+f9715017e60fe29557e37402e70eed9119f84324f880e5bf6f25bc78a4113647
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/bzr1.expected b/tests/cachekey/project/sources/bzr1.expected
index cb276c4c2..25cc7c99b 100644
--- a/tests/cachekey/project/sources/bzr1.expected
+++ b/tests/cachekey/project/sources/bzr1.expected
@@ -1 +1 @@
-a2682d5e230ea207054fef05eecc1bb8ebc856ae12984ca5ab187d648551e917
\ No newline at end of file
+edf2530d3395461ad3e6802944bb023699e0b0a2afb0d4b65f5f35c3c5936154
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/git1.expected b/tests/cachekey/project/sources/git1.expected
index 427db1397..9d6f05770 100644
--- a/tests/cachekey/project/sources/git1.expected
+++ b/tests/cachekey/project/sources/git1.expected
@@ -1 +1 @@
-572276304251917e3ce611b19a6c95cb984d989274405344d307e463c53c6b41
\ No newline at end of file
+74bae7aaf8af955c0a93148830dee097382d806e6aba3a30bdfec62617661b46
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/git2.expected b/tests/cachekey/project/sources/git2.expected
index a481139d9..24f95c7a8 100644
--- a/tests/cachekey/project/sources/git2.expected
+++ b/tests/cachekey/project/sources/git2.expected
@@ -1 +1 @@
-e1c86b2e7a5e87f01a7ea10beacff0c9d2771b39e295729e76db42f2133ad478
\ No newline at end of file
+46fae4a8d6195aa6680d82824167eaa453f8945625869fb4aa0bb774bdbe8bf5
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/local1.expected b/tests/cachekey/project/sources/local1.expected
index b9020e2d0..fdb2911e5 100644
--- a/tests/cachekey/project/sources/local1.expected
+++ b/tests/cachekey/project/sources/local1.expected
@@ -1 +1 @@
-619692c94c9b499eaa23358b45fd75b4526d9f5b6d3a6061faad9b6726510db3
\ No newline at end of file
+92a12959aba0d4123f383e8d285e1989877f04074d248b3d5bae801d14801fa0
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/local2.expected b/tests/cachekey/project/sources/local2.expected
index 7a5a9fcc7..69215eceb 100644
--- a/tests/cachekey/project/sources/local2.expected
+++ b/tests/cachekey/project/sources/local2.expected
@@ -1 +1 @@
-080e7416809ccc1a433e28263f6d719c2ac18047ea6def5991ef0dbd049a76f7
\ No newline at end of file
+68b17676ea7156e3c267d07a93041f375c868c10015e8742de365dbe561d810e
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/ostree1.expected b/tests/cachekey/project/sources/ostree1.expected
index b318f5051..eb4c8ddd5 100644
--- a/tests/cachekey/project/sources/ostree1.expected
+++ b/tests/cachekey/project/sources/ostree1.expected
@@ -1 +1 @@
-9ea532e5911bae30f07910a5da05190c74477e4b5038e8aa43e0178c48d85f92
\ No newline at end of file
+f11dc9d54b07608742a6204adbf6dfa74f737b023c4519cc301b5790e3dcf16c
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/patch1.expected b/tests/cachekey/project/sources/patch1.expected
index 8887de99d..3e00ad4e3 100644
--- a/tests/cachekey/project/sources/patch1.expected
+++ b/tests/cachekey/project/sources/patch1.expected
@@ -1 +1 @@
-11cab57689dcbb0afd4ee70d589d41d641e1f103427df51fd1d944ec66edc21b
\ No newline at end of file
+5982cee04b8a10d4fec13fc6463b8be664323c1c44b802146f483f9dd53ca5f6
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/patch2.expected b/tests/cachekey/project/sources/patch2.expected
index 196bfedf4..256470fd6 100644
--- a/tests/cachekey/project/sources/patch2.expected
+++ b/tests/cachekey/project/sources/patch2.expected
@@ -1 +1 @@
-4ab69bc0ecbe926e5659a11bb3b82ac0e5155f1571923b1a57668ce93f27cb46
\ No newline at end of file
+95188e54e87a869450049f5b7e865e3f3762d4d387b930c39199ef3b7864fad8
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/patch3.expected b/tests/cachekey/project/sources/patch3.expected
index abac783cd..351f35ec8 100644
--- a/tests/cachekey/project/sources/patch3.expected
+++ b/tests/cachekey/project/sources/patch3.expected
@@ -1 +1 @@
-d2d943fa7e0bc7188eaa461d9b92c23aee43361c279106d92dd5f2260ebf8110
\ No newline at end of file
+43c215e5be4402eff02f23cd5d1b83659a942b17a56a4c373c36333fcc07fd76
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/pip1.expected b/tests/cachekey/project/sources/pip1.expected
index 7ab6fd13f..7f0cd5d31 100644
--- a/tests/cachekey/project/sources/pip1.expected
+++ b/tests/cachekey/project/sources/pip1.expected
@@ -1 +1 @@
-a36bfabe4365076681469b8b6f580d1adb7da5d88a69c168a7bb831fa15651a7
\ No newline at end of file
+77241a36a6dc2b89b99e8e8dc52dd057f6f78319a7ff913291aa44419b6afab9
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/tar1.expected b/tests/cachekey/project/sources/tar1.expected
index 0e657b4a7..1c892d4a7 100644
--- a/tests/cachekey/project/sources/tar1.expected
+++ b/tests/cachekey/project/sources/tar1.expected
@@ -1 +1 @@
-a284396dae1e98302c98b150d1bb04b576d3039bea138fe0244c3cde6d5ccea5
\ No newline at end of file
+2a75001c338b720fac8d5d30933c9ffa14f7e9ef1ebd22c9cf67b6dfc7e94dae
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/tar2.expected b/tests/cachekey/project/sources/tar2.expected
index 720ea6cfd..4eca37ece 100644
--- a/tests/cachekey/project/sources/tar2.expected
+++ b/tests/cachekey/project/sources/tar2.expected
@@ -1 +1 @@
-db0d89c04aa964931ee65c456ae91aa2cb784c189f03f2ad36c3ba91381c2005
\ No newline at end of file
+0056ada224a0e4c25be48c2b0940b7431af8c79b56cbd5556b7e96c9840060e2
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/zip1.expected b/tests/cachekey/project/sources/zip1.expected
index 799277681..101b3f704 100644
--- a/tests/cachekey/project/sources/zip1.expected
+++ b/tests/cachekey/project/sources/zip1.expected
@@ -1 +1 @@
-d106ec29cbd3d04f54d6416edb2300d3e7acb5cb21b231efa6e9f251384d7bc0
\ No newline at end of file
+74daf0d1bf5cd07ba420fc059addf2b6e3cb58596b61ebead5ec15830ec8dc63
\ No newline at end of file
diff --git a/tests/cachekey/project/sources/zip2.expected b/tests/cachekey/project/sources/zip2.expected
index 82ea3c545..5bcc7f2b8 100644
--- a/tests/cachekey/project/sources/zip2.expected
+++ b/tests/cachekey/project/sources/zip2.expected
@@ -1 +1 @@
-5085978ab2f7f228a6d58ddad945d146d353be6f313e9e13981b7f3a88819d72
\ No newline at end of file
+7ebc6f246a7cba793116c7c1ebeba02eab3abadd527f6b3a239f025380f3682b
\ No newline at end of file
diff --git a/tests/cachekey/project/target.expected b/tests/cachekey/project/target.expected
index 36b583e1d..acf8ab631 100644
--- a/tests/cachekey/project/target.expected
+++ b/tests/cachekey/project/target.expected
@@ -1 +1 @@
-7534baaacec89d9583a09aa016979c182b5c22f946100050ee5fb44a07ab554d
+1d3465903d45365032bff340ec8a8bf0e7d69f4332bb3c525d228a04009dcff7
\ No newline at end of file
diff --git a/tests/frontend/overlaps.py b/tests/frontend/overlaps.py
index 7c86445f6..1a2f37d0d 100644
--- a/tests/frontend/overlaps.py
+++ b/tests/frontend/overlaps.py
@@ -4,6 +4,7 @@ from tests.testutils.runcli import cli
 from tests.testutils import generate_junction
 from buildstream._exceptions import ErrorDomain
 from buildstream import _yaml
+from buildstream.plugin import CoreWarnings
 
 # Project directory
 DATA_DIR = os.path.join(
@@ -12,32 +13,37 @@ DATA_DIR = os.path.join(
 )
 
 
-def gen_project(project_dir, fail_on_overlap, project_name="test"):
+def gen_project(project_dir, fail_on_overlap, use_fatal_warnings=True, project_name="test"):
     template = {
         "name": project_name,
-        "fail-on-overlap": fail_on_overlap
     }
+    if use_fatal_warnings:
+        template["fatal-warnings"] = [CoreWarnings.OVERLAPS] if fail_on_overlap else []
+    else:
+        template["fail-on-overlap"] = fail_on_overlap
     projectfile = os.path.join(project_dir, "project.conf")
     _yaml.dump(template, projectfile)
 
 
 @pytest.mark.datafiles(DATA_DIR)
-def test_overlaps(cli, datafiles):
+@pytest.mark.parametrize("use_fatal_warnings", [True, False])
+def test_overlaps(cli, datafiles, use_fatal_warnings):
     project_dir = str(datafiles)
-    gen_project(project_dir, False)
+    gen_project(project_dir, False, use_fatal_warnings)
     result = cli.run(project=project_dir, silent=True, args=[
         'build', 'collect.bst'])
     result.assert_success()
 
 
 @pytest.mark.datafiles(DATA_DIR)
-def test_overlaps_error(cli, datafiles):
+@pytest.mark.parametrize("use_fatal_warnings", [True, False])
+def test_overlaps_error(cli, datafiles, use_fatal_warnings):
     project_dir = str(datafiles)
-    gen_project(project_dir, True)
+    gen_project(project_dir, True, use_fatal_warnings)
     result = cli.run(project=project_dir, silent=True, args=[
         'build', 'collect.bst'])
     result.assert_main_error(ErrorDomain.STREAM, None)
-    result.assert_task_error(ErrorDomain.ELEMENT, "overlap-error")
+    result.assert_task_error(ErrorDomain.PLUGIN, CoreWarnings.OVERLAPS)
 
 
 @pytest.mark.datafiles(DATA_DIR)
@@ -68,15 +74,16 @@ def test_overlaps_whitelist_on_overlapper(cli, datafiles):
     result = cli.run(project=project_dir, silent=True, args=[
         'build', 'collect-partially-whitelisted.bst'])
     result.assert_main_error(ErrorDomain.STREAM, None)
-    result.assert_task_error(ErrorDomain.ELEMENT, "overlap-error")
+    result.assert_task_error(ErrorDomain.PLUGIN, CoreWarnings.OVERLAPS)
 
 
 @pytest.mark.datafiles(DATA_DIR)
-def test_overlaps_script(cli, datafiles):
+@pytest.mark.parametrize("use_fatal_warnings", [True, False])
+def test_overlaps_script(cli, datafiles, use_fatal_warnings):
     # Test overlaps with script element to test
     # Element.stage_dependency_artifacts() with Scope.RUN
     project_dir = str(datafiles)
-    gen_project(project_dir, False)
+    gen_project(project_dir, False, use_fatal_warnings)
     result = cli.run(project=project_dir, silent=True, args=[
         'build', 'script.bst'])
     result.assert_success()