From 9f401fe3c4c6d64081aefe49f4630b3c138115c5 Mon Sep 17 00:00:00 2001
From: Mel Hall <37735232+datamel@users.noreply.github.com>
Date: Tue, 9 Nov 2021 11:14:27 +0000
Subject: [PATCH 01/11] Remove the suite.rc flow.cylc symlink

---
 CHANGES.md                                    |  3 +
 cylc/flow/workflow_files.py                   | 64 ++++++-------------
 tests/functional/cylc-install/00-simple.t     | 17 +----
 tests/functional/cylc-install/02-failures.t   |  4 +-
 tests/functional/cylc-reinstall/00-simple.t   | 24 +------
 .../cylc-reinstall/01-file-transfer.t         | 18 +-----
 tests/functional/cylc-reinstall/02-failures.t |  4 +-
 tests/functional/deprecations/03-suiterc.t    | 18 +-----
 .../optional-outputs/03-c7backcompat.t        |  3 +-
 tests/unit/test_workflow_files.py             |  4 +-
 10 files changed, 35 insertions(+), 124 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index d92f219b869..470cb3c7ebe 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -56,6 +56,9 @@ First Release Candidate for Cylc 8.
 
 ### Enhancements
 
+[#](https://github.com/cylc/cylc-flow/pull/) -
+Cylc no longer creates a `flow.cylc` symlink to a `suite.rc` file.
+
 [#4526](https://github.com/cylc/cylc-flow/pull/4526) - Prevent runN and run\d+
 being allowed as installation target names.
 
diff --git a/cylc/flow/workflow_files.py b/cylc/flow/workflow_files.py
index 9b312247171..cdd09d40dc7 100644
--- a/cylc/flow/workflow_files.py
+++ b/cylc/flow/workflow_files.py
@@ -84,7 +84,6 @@
 
 if TYPE_CHECKING:
     from optparse import Values
-    from logging import Logger
 
 
 class KeyType(Enum):
@@ -551,8 +550,8 @@ def get_flow_file(reg: str) -> str:
     Creates a flow.cylc symlink to suite.rc if only suite.rc exists.
     """
     run_dir = get_workflow_run_dir(reg)
-    check_flow_file(run_dir, symlink_suiterc=True)
-    return os.path.join(run_dir, WorkflowFiles.FLOW_FILE)
+    path = check_flow_file(run_dir)
+    return path
 
 
 def get_workflow_source_dir(
@@ -678,7 +677,7 @@ def register(
         source = os.getcwd()
     # flow.cylc must exist so we can detect accidentally reversed args.
     source = os.path.abspath(source)
-    check_flow_file(source, symlink_suiterc=True, logger=None)
+    check_flow_file(source)
     if not is_installed(get_workflow_run_dir(workflow_name)):
         symlinks_created = make_localhost_symlinks(
             get_workflow_run_dir(workflow_name), workflow_name)
@@ -1297,7 +1296,7 @@ def _parse_src_reg(reg: Path, cur_dir_only: bool = False) -> Tuple[Path, Path]:
                         ))
                 else:
                     try:
-                        abs_path = check_flow_file(abs_path, logger=None)
+                        abs_path = check_flow_file(abs_path)
                     except WorkflowFilesError:
                         return (run_dir_reg, run_dir_path)
                     LOG.warning(REG_CLASH_MSG.format(
@@ -1587,7 +1586,7 @@ def reinstall_workflow(named_run, rundir, source, dry_run=False):
         reinstall_log.warning(
             f"An error occurred when copying files from {source} to {rundir}")
         reinstall_log.warning(f" Error: {stderr}")
-    check_flow_file(rundir, symlink_suiterc=True, logger=reinstall_log)
+    check_flow_file(rundir)
     reinstall_log.info(f'REINSTALLED {named_run} from {source}')
     print(f'REINSTALLED {named_run} from {source}')
     close_log(reinstall_log)
@@ -1691,7 +1690,7 @@ def install_workflow(
         install_log.warning(f" Warning: {stderr}")
     cylc_install = Path(rundir.parent, WorkflowFiles.Install.DIRNAME)
     check_deprecation(
-        check_flow_file(rundir, symlink_suiterc=True, logger=install_log)
+        check_flow_file(rundir)
     )
     if no_run_name:
         cylc_install = Path(rundir, WorkflowFiles.Install.DIRNAME)
@@ -1761,11 +1760,13 @@ def get_run_dir_info(
 
 def detect_both_flow_and_suite(path):
     """Detects if both suite.rc and flow.cylc are in directory.
+
+    Permits flow.cylc to be a symlink.
     Raises:
         WorkflowFilesError: If both flow.cylc and suite.rc are in directory
     """
     msg = (f"Both {WorkflowFiles.FLOW_FILE} and {WorkflowFiles.SUITE_RC} "
-           "files are present in the run directory. Please remove one and"
+           f"files are present in {path}. Please remove one and"
            " try again. For more information visit: https://cylc.github.io/"
            "cylc-doc/latest/html/7-to-8/summary.html#backward-compatibility")
     if path.resolve().name == WorkflowFiles.SUITE_RC:
@@ -1806,53 +1807,30 @@ def detect_flow_exists(
 
 def check_flow_file(
     path: Union[Path, str],
-    symlink_suiterc: bool = False,
-    logger: Optional['Logger'] = LOG
 ) -> Path:
-    """Raises WorkflowFilesError if no flow file in path sent.
+    """Checks the path for a suite.rc or flow.cylc file.
+
+    Raises:
+        WorkflowFilesError
+            - if no flow file in path sent
+            - both suite.rc and flow.cylc in path sent.
 
     Args:
         path: Absolute path to check for a flow.cylc and/or suite.rc file.
-        symlink_suiterc: If True and suite.rc exists, create flow.cylc as a
-            symlink to suite.rc. If a flow.cylc symlink already exists but
-            points elsewhere, it will be replaced.
-        logger: A custom logger to use to log warnings.
 
     Returns the path of the flow file if present.
     """
     flow_file_path = Path(expand_path(path), WorkflowFiles.FLOW_FILE)
     suite_rc_path = Path(expand_path(path), WorkflowFiles.SUITE_RC)
     if flow_file_path.is_file():
-        if not flow_file_path.is_symlink():
-            if not suite_rc_path.is_file():
-                return flow_file_path
-            raise WorkflowFilesError(
-                f"Both {WorkflowFiles.FLOW_FILE} and "
-                f"{WorkflowFiles.SUITE_RC} files are present in the source "
-                "directory. Please remove one and try again. For more "
-                "information visit: https://cylc.github.io/cylc-doc/latest/"
-                "html/7-to-8/summary.html#backward-compatibility"
-            )
-        if flow_file_path.resolve() == suite_rc_path.resolve():
-            # A symlink that points to existing suite.rc
-            return flow_file_path
-    if suite_rc_path.is_file():
-        if not symlink_suiterc:
-            return suite_rc_path
-        if flow_file_path.is_symlink():
-            # Symlink broken or points elsewhere - replace
-            flow_file_path.unlink()
-        flow_file_path.symlink_to(WorkflowFiles.SUITE_RC)
-        if logger:
-            logger.warning(
-                f"Symlink created: "
-                f"{WorkflowFiles.FLOW_FILE} -> {WorkflowFiles.SUITE_RC}"
-            )
+        detect_both_flow_and_suite(Path(path))
         return flow_file_path
+    if suite_rc_path.is_file():
+        return suite_rc_path
     raise WorkflowFilesError(NO_FLOW_FILE_MSG.format(path))
 
 
-def create_workflow_srv_dir(rundir=None, source=None):
+def create_workflow_srv_dir(rundir=None):
     """Create workflow service directory"""
 
     workflow_srv_d = rundir.joinpath(WorkflowFiles.Service.DIRNAME)
@@ -1882,7 +1860,7 @@ def validate_source_dir(source, workflow_name):
         raise WorkflowFilesError(
             f"{workflow_name} installation failed. Source directory "
             f"should not be in {cylc_run_dir}.")
-    check_flow_file(source, logger=None)
+    check_flow_file(source)
 
 
 def parse_cli_sym_dirs(symlink_dirs: str) -> Dict[str, Dict[str, Any]]:
@@ -1964,7 +1942,7 @@ def search_install_source_dirs(workflow_name: str) -> Path:
             "does not contain any paths")
     for path in search_path:
         try:
-            flow_file = check_flow_file(Path(path, workflow_name), logger=None)
+            flow_file = check_flow_file(Path(path, workflow_name))
             return flow_file.parent
         except WorkflowFilesError:
             continue
diff --git a/tests/functional/cylc-install/00-simple.t b/tests/functional/cylc-install/00-simple.t
index ddbf44312da..48e171f3192 100755
--- a/tests/functional/cylc-install/00-simple.t
+++ b/tests/functional/cylc-install/00-simple.t
@@ -18,7 +18,7 @@
 #------------------------------------------------------------------------------
 # Test workflow installation
 . "$(dirname "$0")/test_header"
-set_test_number 29
+set_test_number 25
 
 create_test_global_config "" "
 [install]
@@ -66,7 +66,6 @@ purge_rnd_workflow
 
 # -----------------------------------------------------------------------------
 # Test cylc install succeeds if suite.rc file in source dir
-# See also tests/functional/deprecations/03-suiterc.t
 TEST_NAME="${TEST_NAME_BASE}-suite.rc"
 make_rnd_workflow
 rm -f "${RND_WORKFLOW_SOURCE}/flow.cylc"
@@ -76,20 +75,6 @@ run_ok "${TEST_NAME}" cylc install --flow-name="${RND_WORKFLOW_NAME}" -C "${RND_
 contains_ok "${TEST_NAME}.stdout" <<__OUT__
 INSTALLED $RND_WORKFLOW_NAME/run1 from ${RND_WORKFLOW_SOURCE}
 __OUT__
-# test symlink not made in source dir
-exists_fail "flow.cylc"
-# test symlink correctly made in run dir
-pushd "${RND_WORKFLOW_RUNDIR}/run1" || exit 1
-exists_ok "flow.cylc"
-
-TEST_NAME="${TEST_NAME_BASE}-suite.rc-flow.cylc-readlink"
-readlink "flow.cylc" > "${TEST_NAME}.out"
-cmp_ok "${TEST_NAME}.out" <<< "suite.rc"
-
-INSTALL_LOG="$(find "${RND_WORKFLOW_RUNDIR}/run1/log/install" -type f -name '*.log')"
-grep_ok "Symlink created: flow.cylc -> suite.rc" "${INSTALL_LOG}"
-popd || exit 1
-
 purge_rnd_workflow
 
 # -----------------------------------------------------------------------------
diff --git a/tests/functional/cylc-install/02-failures.t b/tests/functional/cylc-install/02-failures.t
index 0887191dede..af6c5ad3877 100644
--- a/tests/functional/cylc-install/02-failures.t
+++ b/tests/functional/cylc-install/02-failures.t
@@ -64,8 +64,8 @@ TEST_NAME="${TEST_NAME_BASE}-both-suite-and-flow-file"
 touch "${RND_WORKFLOW_SOURCE}/suite.rc"
 run_fail "${TEST_NAME}" cylc install --flow-name="${RND_WORKFLOW_NAME}" -C "${RND_WORKFLOW_SOURCE}"
 contains_ok "${TEST_NAME}.stderr" <<__ERR__
-WorkflowFilesError: Both flow.cylc and suite.rc files are present in the source \
-directory. Please remove one and try again. For more information visit: \
+WorkflowFilesError: Both flow.cylc and suite.rc files are present in ${RND_WORKFLOW_SOURCE}. \
+Please remove one and try again. For more information visit: \
 https://cylc.github.io/cylc-doc/latest/html/7-to-8/summary.html#backward-compatibility
 __ERR__
 
diff --git a/tests/functional/cylc-reinstall/00-simple.t b/tests/functional/cylc-reinstall/00-simple.t
index f945aad238e..b951e7b4f9e 100644
--- a/tests/functional/cylc-reinstall/00-simple.t
+++ b/tests/functional/cylc-reinstall/00-simple.t
@@ -18,7 +18,7 @@
 #------------------------------------------------------------------------------
 # Test workflow re-installation
 . "$(dirname "$0")/test_header"
-set_test_number 28
+set_test_number 21
 
 # Test basic cylc reinstall, named run given
 TEST_NAME="${TEST_NAME_BASE}-basic-named-run"
@@ -60,30 +60,8 @@ run_ok "${TEST_NAME}" cylc install --flow-name="${RND_WORKFLOW_NAME}" -C "${RND_
 cmp_ok "${TEST_NAME}.stdout" <<__OUT__
 INSTALLED $RND_WORKFLOW_NAME/run1 from ${RND_WORKFLOW_SOURCE}
 __OUT__
-# test symlink not made in source dir
-exists_fail "flow.cylc"
-# test symlink correctly made in run dir
-pushd "${RND_WORKFLOW_RUNDIR}/run1" || exit 1
-exists_ok "flow.cylc"
-if [[ $(readlink "${RND_WORKFLOW_RUNDIR}/run1/flow.cylc") == "suite.rc" ]] ; then
-    ok "symlink.suite.rc"
-else
-    fail "symlink.suite.rc"
-fi
 
-INSTALL_LOG="$(find "${RND_WORKFLOW_RUNDIR}/run1/log/install" -type f -name '*.log')"
-grep_ok "Symlink created: flow.cylc -> suite.rc" "${INSTALL_LOG}"
-rm -rf flow.cylc
 run_ok "${TEST_NAME}-reinstall" cylc reinstall "${RND_WORKFLOW_NAME}/run1"
-exists_ok "${RND_WORKFLOW_RUNDIR}/run1/flow.cylc"
-if [[ $(readlink "${RND_WORKFLOW_RUNDIR}/run1/flow.cylc") == "suite.rc" ]] ; then
-    ok "symlink.suite.rc"
-else
-    fail "symlink.suite.rc"
-fi
-REINSTALL_LOG="$(find "${RND_WORKFLOW_RUNDIR}/run1/log/install" -type f -name '*reinstall.log')"
-grep_ok "Symlink created: flow.cylc -> suite.rc" "${INSTALL_LOG}"
-popd || exit 1
 purge_rnd_workflow
 
 # Test cylc reinstall from within rundir, no args given
diff --git a/tests/functional/cylc-reinstall/01-file-transfer.t b/tests/functional/cylc-reinstall/01-file-transfer.t
index 146c44b5735..dc79cf4c31c 100644
--- a/tests/functional/cylc-reinstall/01-file-transfer.t
+++ b/tests/functional/cylc-reinstall/01-file-transfer.t
@@ -21,7 +21,7 @@
 if ! command -v 'tree' >'/dev/null'; then
     skip_all '"tree" command not available'
 fi
-set_test_number 14
+set_test_number 9
 
 # Test cylc install copies files to run dir successfully.
 TEST_NAME="${TEST_NAME_BASE}-basic"
@@ -88,20 +88,4 @@ cmp_ok 'after-reinstall-run1-tree.out' '01-file-transfer-basic-tree.out'
 popd || exit 1
 purge_rnd_workflow
 
-
-# Test cylc reinstall creates flow.cylc given suite.rc.
-TEST_NAME="${TEST_NAME_BASE}-reinstall-creates-flow.cylc-given-suite.rc"
-make_rnd_workflow
-pushd "${RND_WORKFLOW_SOURCE}" || exit 1
-rm -f flow.cylc
-touch suite.rc
-run_ok "${TEST_NAME}-install" cylc install --no-run-name --flow-name="${RND_WORKFLOW_NAME}"
-rm -f "${RND_WORKFLOW_RUNDIR}/flow.cylc"
-exists_fail "${RND_WORKFLOW_RUNDIR}/flow.cylc"
-run_ok "${TEST_NAME}-reinstall" cylc reinstall "${RND_WORKFLOW_NAME}"
-exists_ok "${RND_WORKFLOW_RUNDIR}/flow.cylc"
-exists_fail "${RND_WORKFLOW_SOURCE}/flow.cylc"
-popd || exit 1
-purge_rnd_workflow
-
 exit
diff --git a/tests/functional/cylc-reinstall/02-failures.t b/tests/functional/cylc-reinstall/02-failures.t
index e13d2486ecc..63f3523b4b4 100644
--- a/tests/functional/cylc-reinstall/02-failures.t
+++ b/tests/functional/cylc-reinstall/02-failures.t
@@ -65,8 +65,8 @@ run_ok "${TEST_NAME}-install" cylc install -C "${RND_WORKFLOW_SOURCE}" --flow-na
 touch "${RND_WORKFLOW_SOURCE}/suite.rc"
 run_fail "${TEST_NAME}" cylc reinstall "${RND_WORKFLOW_NAME}"
 cmp_ok "${TEST_NAME}.stderr" <<__ERR__
-WorkflowFilesError: Both flow.cylc and suite.rc files are present in the source \
-directory. Please remove one and try again. For more information visit: \
+WorkflowFilesError: Both flow.cylc and suite.rc files are present in ${RND_WORKFLOW_SOURCE}. \
+Please remove one and try again. For more information visit: \
 https://cylc.github.io/cylc-doc/latest/html/7-to-8/summary.html#backward-compatibility
 __ERR__
 purge_rnd_workflow
diff --git a/tests/functional/deprecations/03-suiterc.t b/tests/functional/deprecations/03-suiterc.t
index f8248591fef..0faa15e1b93 100644
--- a/tests/functional/deprecations/03-suiterc.t
+++ b/tests/functional/deprecations/03-suiterc.t
@@ -18,7 +18,7 @@
 # Test backwards compatibility for suite.rc files
 
 . "$(dirname "$0")/test_header"
-set_test_number 5
+set_test_number 2
 
 init_suiterc() {
     local TEST_NAME="$1"
@@ -44,19 +44,3 @@ print(SUITERC_DEPR_MSG)')
 TEST_NAME="${TEST_NAME_BASE}-validate"
 run_ok "${TEST_NAME}" cylc validate .
 grep_ok "$MSG" "${TEST_NAME_BASE}-validate.stderr"
-
-# Test install suite.rc
-# See also tests/functional/cylc-install/00-simple.t
-TEST_NAME="${TEST_NAME_BASE}-install-after-validate"
-run_ok "${TEST_NAME}" cylc install --flow-name="${WORKFLOW_NAME}" --no-run-name
-
-cd "${WORKFLOW_RUN_DIR}" || exit 1
-exists_ok "flow.cylc"
-
-TEST_NAME="flow.cylc-readlink"
-readlink "flow.cylc" > "${TEST_NAME}.out"
-cmp_ok "${TEST_NAME}.out" <<< "suite.rc"
-
-cd "${TEST_DIR}" || exit 1
-rm -rf "${TEST_DIR:?}/${WORKFLOW_NAME}/"
-purge
diff --git a/tests/functional/optional-outputs/03-c7backcompat.t b/tests/functional/optional-outputs/03-c7backcompat.t
index 3da19fa7d10..83f2119694b 100644
--- a/tests/functional/optional-outputs/03-c7backcompat.t
+++ b/tests/functional/optional-outputs/03-c7backcompat.t
@@ -35,8 +35,7 @@ grep_ok "${ERR}" "${TEST_NAME}.stderr"
 
 # Rename config to "suite.rc"
 mv "${WORKFLOW_RUN_DIR}/flow.cylc" "${WORKFLOW_RUN_DIR}/suite.rc"
-ln -s "${WORKFLOW_RUN_DIR}/suite.rc" "${WORKFLOW_RUN_DIR}/flow.cylc" 
-
+-ln -s "${WORKFLOW_RUN_DIR}/suite.rc" "${WORKFLOW_RUN_DIR}/flow.cylc"
 # It should now validate, with a deprecation message
 TEST_NAME="${TEST_NAME_BASE}-validate_as_c7"
 run_ok "${TEST_NAME}" cylc validate "${WORKFLOW_NAME}"
diff --git a/tests/unit/test_workflow_files.py b/tests/unit/test_workflow_files.py
index 4849f8f24f6..78a3eea1b0d 100644
--- a/tests/unit/test_workflow_files.py
+++ b/tests/unit/test_workflow_files.py
@@ -1805,8 +1805,8 @@ def test_check_flow_file(
         with pytest.raises(WorkflowFilesError) as exc:
             check_flow_file(tmp_path)
         assert str(exc.value) == (
-            "Both flow.cylc and suite.rc files are present in the "
-            "source directory. Please remove one and try again. "
+            "Both flow.cylc and suite.rc files are present in "
+            f"{tmp_path}. Please remove one and try again. "
             "For more information visit: "
             "https://cylc.github.io/cylc-doc/latest/html/7-to-8/summary.html"
             "#backward-compatibility"

From c14db21b94d543fc20822fc8698700390a9aadf1 Mon Sep 17 00:00:00 2001
From: Mel Hall <37735232+datamel@users.noreply.github.com>
Date: Wed, 10 Nov 2021 18:19:52 +0000
Subject: [PATCH 02/11] change log

---
 CHANGES.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGES.md b/CHANGES.md
index 470cb3c7ebe..ebbf0be9e72 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -56,7 +56,7 @@ First Release Candidate for Cylc 8.
 
 ### Enhancements
 
-[#](https://github.com/cylc/cylc-flow/pull/) -
+[#4506](https://github.com/cylc/cylc-flow/pull/4506) -
 Cylc no longer creates a `flow.cylc` symlink to a `suite.rc` file.
 
 [#4526](https://github.com/cylc/cylc-flow/pull/4526) - Prevent runN and run\d+

From a4354b6f5b523a00df9235ec5251c230af934023 Mon Sep 17 00:00:00 2001
From: Mel Hall <37735232+datamel@users.noreply.github.com>
Date: Mon, 15 Nov 2021 10:17:06 +0000
Subject: [PATCH 03/11] shellcheck

---
 tests/functional/deprecations/03-suiterc.t          | 1 -
 tests/functional/optional-outputs/03-c7backcompat.t | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/tests/functional/deprecations/03-suiterc.t b/tests/functional/deprecations/03-suiterc.t
index 0faa15e1b93..7fdfa6f6f1e 100644
--- a/tests/functional/deprecations/03-suiterc.t
+++ b/tests/functional/deprecations/03-suiterc.t
@@ -24,7 +24,6 @@ init_suiterc() {
     local TEST_NAME="$1"
     local FLOW_CONFIG="${2:--}"
     WORKFLOW_NAME="${CYLC_TEST_REG_BASE}/${TEST_SOURCE_DIR_BASE}/${TEST_NAME}"
-    WORKFLOW_RUN_DIR="$RUN_DIR/$WORKFLOW_NAME"
     mkdir -p "${TEST_DIR}/${WORKFLOW_NAME}/"
     cat "${FLOW_CONFIG}" >"${TEST_DIR}/${WORKFLOW_NAME}/suite.rc"
     cd "${TEST_DIR}/${WORKFLOW_NAME}" || exit
diff --git a/tests/functional/optional-outputs/03-c7backcompat.t b/tests/functional/optional-outputs/03-c7backcompat.t
index 83f2119694b..432430e09bf 100644
--- a/tests/functional/optional-outputs/03-c7backcompat.t
+++ b/tests/functional/optional-outputs/03-c7backcompat.t
@@ -35,7 +35,7 @@ grep_ok "${ERR}" "${TEST_NAME}.stderr"
 
 # Rename config to "suite.rc"
 mv "${WORKFLOW_RUN_DIR}/flow.cylc" "${WORKFLOW_RUN_DIR}/suite.rc"
--ln -s "${WORKFLOW_RUN_DIR}/suite.rc" "${WORKFLOW_RUN_DIR}/flow.cylc"
+ln -s "${WORKFLOW_RUN_DIR}/suite.rc" "${WORKFLOW_RUN_DIR}/flow.cylc"
 # It should now validate, with a deprecation message
 TEST_NAME="${TEST_NAME_BASE}-validate_as_c7"
 run_ok "${TEST_NAME}" cylc validate "${WORKFLOW_NAME}"

From d638b3ecc755c24f3e6da6e08a69213e866a44a5 Mon Sep 17 00:00:00 2001
From: Mel Hall <37735232+datamel@users.noreply.github.com>
Date: Fri, 26 Nov 2021 12:02:00 +0000
Subject: [PATCH 04/11] Review feedback and add checks to suite.rc and
 flow.cylc file logic.

---
 CHANGES.md                        |  1 +
 cylc/flow/workflow_files.py       | 33 ++++++++++++++++----
 tests/unit/test_workflow_files.py | 50 ++++++++++++++++++++++++++++++-
 3 files changed, 77 insertions(+), 7 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index ebbf0be9e72..ce66f02b434 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -58,6 +58,7 @@ First Release Candidate for Cylc 8.
 
 [#4506](https://github.com/cylc/cylc-flow/pull/4506) -
 Cylc no longer creates a `flow.cylc` symlink to a `suite.rc` file.
+This only affects you if you have used a prior Cylc 8 pre-release.
 
 [#4526](https://github.com/cylc/cylc-flow/pull/4526) - Prevent runN and run\d+
 being allowed as installation target names.
diff --git a/cylc/flow/workflow_files.py b/cylc/flow/workflow_files.py
index cdd09d40dc7..a8fec4eccae 100644
--- a/cylc/flow/workflow_files.py
+++ b/cylc/flow/workflow_files.py
@@ -544,7 +544,7 @@ def get_contact_file(reg):
         get_workflow_srv_dir(reg), WorkflowFiles.Service.CONTACT)
 
 
-def get_flow_file(reg: str) -> str:
+def get_flow_file(reg: str) -> Path:
     """Return the path of a workflow's flow.cylc file.
 
     Creates a flow.cylc symlink to suite.rc if only suite.rc exists.
@@ -1758,25 +1758,46 @@ def get_run_dir_info(
     return relink, run_num, rundir
 
 
-def detect_both_flow_and_suite(path):
+def detect_both_flow_and_suite(path: Path) -> None:
     """Detects if both suite.rc and flow.cylc are in directory.
 
     Permits flow.cylc to be a symlink.
+    Return true if present, raises error if flow.cylc path sent is a forbidden
+    symlink.
     Raises:
         WorkflowFilesError: If both flow.cylc and suite.rc are in directory
     """
+    flow_cylc = None
     msg = (f"Both {WorkflowFiles.FLOW_FILE} and {WorkflowFiles.SUITE_RC} "
            f"files are present in {path}. Please remove one and"
            " try again. For more information visit: https://cylc.github.io/"
            "cylc-doc/latest/html/7-to-8/summary.html#backward-compatibility")
     if path.resolve().name == WorkflowFiles.SUITE_RC:
         flow_cylc = path.parent / WorkflowFiles.FLOW_FILE
-        if flow_cylc.is_file() and not flow_cylc.is_symlink():
-            raise WorkflowFilesError(msg)
     elif (path / WorkflowFiles.SUITE_RC).is_file():
         flow_cylc = path / WorkflowFiles.FLOW_FILE
-        if flow_cylc.is_file() and not flow_cylc.is_symlink():
-            raise WorkflowFilesError(msg)
+    if flow_cylc and flow_cylc.is_file() and is_forbidden(flow_cylc):
+        raise WorkflowFilesError(msg)
+
+
+def is_forbidden(flow_file: Path) -> bool:
+    """Returns True for a forbidden file structure scenario.
+
+    Forbidden criteria:
+        A symlink elsewhere on file system but suite.rc also exists in the
+        directory.
+        flow.cylc and suite.rc in same directory but no symlink
+    Args:
+        flow_file : Absolute Path to the flow.cylc file
+    """
+    if not flow_file.is_symlink():
+        if flow_file.parent.joinpath(WorkflowFiles.SUITE_RC).exists():
+            return True
+        return False
+    link = flow_file.resolve()
+    if Path(link).parent == flow_file.parent:  # link points within dir
+        return False
+    return True
 
 
 def detect_flow_exists(
diff --git a/tests/unit/test_workflow_files.py b/tests/unit/test_workflow_files.py
index 78a3eea1b0d..1ff96f17d0e 100644
--- a/tests/unit/test_workflow_files.py
+++ b/tests/unit/test_workflow_files.py
@@ -52,6 +52,7 @@
     glob_in_run_dir,
     infer_latest_run,
     init_clean,
+    is_forbidden,
     is_installed,
     parse_cli_sym_dirs,
     parse_reg,
@@ -1817,10 +1818,12 @@ def test_check_flow_file(
 
 
 def test_detect_both_flow_and_suite(tmp_path):
-    """Test flow.cylc and suite.rc together in dir raises error."""
+    """Test flow.cylc and suite.rc (as files) together in dir raises error."""
     tmp_path.joinpath(WorkflowFiles.FLOW_FILE).touch()
     tmp_path.joinpath(WorkflowFiles.SUITE_RC).touch()
 
+    forbidden = is_forbidden(tmp_path / WorkflowFiles.FLOW_FILE)
+    assert forbidden is True
     with pytest.raises(WorkflowFilesError) as exc:
         detect_both_flow_and_suite(tmp_path)
         assert str(exc.value) == (
@@ -1915,6 +1918,51 @@ def test_check_flow_file_symlink(
         assert log_msg in caplog.messages
 
 
+def test_detect_both_flow_and_suite_symlinked(tmp_path):
+    """Test flow.cylc symlinked to suite.rc together in dir is permitted."""
+    Path(tmp_path)
+    (tmp_path / WorkflowFiles.SUITE_RC).touch()
+    flow_file = tmp_path.joinpath(WorkflowFiles.FLOW_FILE)
+    flow_file.symlink_to(WorkflowFiles.SUITE_RC)
+    try:
+        detect_both_flow_and_suite(tmp_path)
+    except WorkflowFilesError:
+        pytest.fail("Unexpected WorkflowFilesError")
+
+
+def test_flow_symlinked_elsewhere_and_suite_present(tmp_path):
+    """flow.cylc symlinked to suite.rc elsewhere, and suite.rc in dir raises"""
+    tmp_path = Path(tmp_path)
+    tmp_path.joinpath('some_other_dir').mkdir(exist_ok=True)
+    suite_file = tmp_path.joinpath('some_other_dir', WorkflowFiles.SUITE_RC)
+    suite_file.touch()
+    run_dir = tmp_path.joinpath('run_dir')
+    run_dir.mkdir(exist_ok=True)
+    flow_file = (run_dir / WorkflowFiles.FLOW_FILE)
+    flow_file.symlink_to(suite_file)
+    (run_dir / WorkflowFiles.SUITE_RC).touch()
+    forbidden = is_forbidden(flow_file)
+    assert forbidden is True
+    with pytest.raises(WorkflowFilesError) as exc:
+        detect_both_flow_and_suite(run_dir)
+        assert str(exc.value) == (
+            "Both flow.cylc and suite.rc files are present in the "
+            "source directory. Please remove one and try again. "
+            "For more information visit: "
+            "https://cylc.github.io/cylc-doc/latest/html/7-to-8/summary.html"
+            "#backward-compatibility"
+        )
+
+
+def test_is_forbidden_symlink_returns_false_for_non_symlink(tmp_path):
+    """Test sending a non symlink path is not marked as forbidden"""
+    Path(tmp_path)
+    flow_file = (tmp_path / WorkflowFiles.FLOW_FILE)
+    flow_file.touch()
+    forbidden = is_forbidden(Path(flow_file))
+    assert forbidden is False
+
+
 @pytest.mark.parametrize(
     'symlink_dirs, err_msg, expected',
     [

From e42f548440f668d03258efbb0d1a5381c84ac2a7 Mon Sep 17 00:00:00 2001
From: Melanie Hall <37735232+datamel@users.noreply.github.com>
Date: Fri, 26 Nov 2021 13:50:06 +0000
Subject: [PATCH 05/11] Update cylc/flow/workflow_files.py

Co-authored-by: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>
---
 cylc/flow/workflow_files.py       | 7 ++-----
 tests/unit/test_workflow_files.py | 9 ++-------
 2 files changed, 4 insertions(+), 12 deletions(-)

diff --git a/cylc/flow/workflow_files.py b/cylc/flow/workflow_files.py
index a8fec4eccae..ae4e8e32e85 100644
--- a/cylc/flow/workflow_files.py
+++ b/cylc/flow/workflow_files.py
@@ -545,10 +545,7 @@ def get_contact_file(reg):
 
 
 def get_flow_file(reg: str) -> Path:
-    """Return the path of a workflow's flow.cylc file.
-
-    Creates a flow.cylc symlink to suite.rc if only suite.rc exists.
-    """
+    """Return the path of a workflow's flow.cylc file."""
     run_dir = get_workflow_run_dir(reg)
     path = check_flow_file(run_dir)
     return path
@@ -1851,7 +1848,7 @@ def check_flow_file(
     raise WorkflowFilesError(NO_FLOW_FILE_MSG.format(path))
 
 
-def create_workflow_srv_dir(rundir=None):
+def create_workflow_srv_dir(rundir: Path) -> None:
     """Create workflow service directory"""
 
     workflow_srv_d = rundir.joinpath(WorkflowFiles.Service.DIRNAME)
diff --git a/tests/unit/test_workflow_files.py b/tests/unit/test_workflow_files.py
index 1ff96f17d0e..5473bbc0fb0 100644
--- a/tests/unit/test_workflow_files.py
+++ b/tests/unit/test_workflow_files.py
@@ -1920,19 +1920,14 @@ def test_check_flow_file_symlink(
 
 def test_detect_both_flow_and_suite_symlinked(tmp_path):
     """Test flow.cylc symlinked to suite.rc together in dir is permitted."""
-    Path(tmp_path)
     (tmp_path / WorkflowFiles.SUITE_RC).touch()
     flow_file = tmp_path.joinpath(WorkflowFiles.FLOW_FILE)
     flow_file.symlink_to(WorkflowFiles.SUITE_RC)
-    try:
-        detect_both_flow_and_suite(tmp_path)
-    except WorkflowFilesError:
-        pytest.fail("Unexpected WorkflowFilesError")
+    detect_both_flow_and_suite(tmp_path)
 
 
-def test_flow_symlinked_elsewhere_and_suite_present(tmp_path):
+def test_flow_symlinked_elsewhere_and_suite_present(tmp_path: Path):
     """flow.cylc symlinked to suite.rc elsewhere, and suite.rc in dir raises"""
-    tmp_path = Path(tmp_path)
     tmp_path.joinpath('some_other_dir').mkdir(exist_ok=True)
     suite_file = tmp_path.joinpath('some_other_dir', WorkflowFiles.SUITE_RC)
     suite_file.touch()

From 0beeac48e14696771c6c7407c5a15546e5d34c59 Mon Sep 17 00:00:00 2001
From: Mel Hall <37735232+datamel@users.noreply.github.com>
Date: Mon, 29 Nov 2021 11:49:49 +0000
Subject: [PATCH 06/11] Add test and tweak logic to permit symlinks elsewhere
 for flow.cylc file

add test for deprecation message cylc install
---
 cylc/flow/workflow_files.py               | 16 ++---
 tests/functional/cylc-install/00-simple.t | 11 ++-
 tests/unit/test_workflow_files.py         | 86 +----------------------
 3 files changed, 19 insertions(+), 94 deletions(-)

diff --git a/cylc/flow/workflow_files.py b/cylc/flow/workflow_files.py
index ae4e8e32e85..b5e92959b93 100644
--- a/cylc/flow/workflow_files.py
+++ b/cylc/flow/workflow_files.py
@@ -1686,9 +1686,7 @@ def install_workflow(
             f"An error occurred when copying files from {source} to {rundir}")
         install_log.warning(f" Warning: {stderr}")
     cylc_install = Path(rundir.parent, WorkflowFiles.Install.DIRNAME)
-    check_deprecation(
-        check_flow_file(rundir)
-    )
+    check_deprecation(check_flow_file(rundir))
     if no_run_name:
         cylc_install = Path(rundir, WorkflowFiles.Install.DIRNAME)
     source_link = cylc_install.joinpath(WorkflowFiles.Install.SOURCE)
@@ -1792,9 +1790,13 @@ def is_forbidden(flow_file: Path) -> bool:
             return True
         return False
     link = flow_file.resolve()
-    if Path(link).parent == flow_file.parent:  # link points within dir
+    if link.parent == flow_file.parent:
+        # link points within dir (permitted)
         return False
-    return True
+    # link points elsewhere, check that suite.rc does not also exist in dir
+    if flow_file.parent.joinpath(WorkflowFiles.SUITE_RC).exists():
+        return True
+    return False
 
 
 def detect_flow_exists(
@@ -1823,9 +1825,7 @@ def detect_flow_exists(
     return False
 
 
-def check_flow_file(
-    path: Union[Path, str],
-) -> Path:
+def check_flow_file(path: Union[Path, str]) -> Path:
     """Checks the path for a suite.rc or flow.cylc file.
 
     Raises:
diff --git a/tests/functional/cylc-install/00-simple.t b/tests/functional/cylc-install/00-simple.t
index 48e171f3192..be839f48c1d 100755
--- a/tests/functional/cylc-install/00-simple.t
+++ b/tests/functional/cylc-install/00-simple.t
@@ -18,7 +18,7 @@
 #------------------------------------------------------------------------------
 # Test workflow installation
 . "$(dirname "$0")/test_header"
-set_test_number 25
+set_test_number 26
 
 create_test_global_config "" "
 [install]
@@ -71,10 +71,17 @@ make_rnd_workflow
 rm -f "${RND_WORKFLOW_SOURCE}/flow.cylc"
 touch "${RND_WORKFLOW_SOURCE}/suite.rc"
 run_ok "${TEST_NAME}" cylc install --flow-name="${RND_WORKFLOW_NAME}" -C "${RND_WORKFLOW_SOURCE}"
-
 contains_ok "${TEST_NAME}.stdout" <<__OUT__
 INSTALLED $RND_WORKFLOW_NAME/run1 from ${RND_WORKFLOW_SOURCE}
 __OUT__
+
+# Test deprecation message is displayed on installing a suite.rc file
+MSG=$(python -c 'from cylc.flow.workflow_files import SUITERC_DEPR_MSG;
+print(SUITERC_DEPR_MSG)')
+
+grep_ok "$MSG" "${TEST_NAME}.stderr"
+
+
 purge_rnd_workflow
 
 # -----------------------------------------------------------------------------
diff --git a/tests/unit/test_workflow_files.py b/tests/unit/test_workflow_files.py
index 5473bbc0fb0..14ebe659bc1 100644
--- a/tests/unit/test_workflow_files.py
+++ b/tests/unit/test_workflow_files.py
@@ -1835,89 +1835,6 @@ def test_detect_both_flow_and_suite(tmp_path):
         )
 
 
-@pytest.mark.parametrize(
-    'flow_file_target, suiterc_exists, err, expected_file',
-    [
-        pytest.param(
-            WorkflowFiles.SUITE_RC, True, None, WorkflowFiles.FLOW_FILE,
-            id="flow.cylc symlinked to suite.rc"
-        ),
-        pytest.param(
-            WorkflowFiles.SUITE_RC, False, WorkflowFilesError, None,
-            id="flow.cylc symlinked to non-existent suite.rc"
-        ),
-        pytest.param(
-            'other-path', True, None, WorkflowFiles.SUITE_RC,
-            id="flow.cylc symlinked to other file, suite.rc exists"
-        ),
-        pytest.param(
-            'other-path', False, WorkflowFilesError, None,
-            id="flow.cylc symlinked to other file, no suite.rc"
-        ),
-        pytest.param(
-            None, True, None, WorkflowFiles.SUITE_RC,
-            id="No flow.cylc, suite.rc exists"
-        ),
-        pytest.param(
-            None, False, WorkflowFilesError, None,
-            id="No flow.cylc, no suite.rc"
-        ),
-    ]
-)
-@pytest.mark.parametrize(
-    'symlink_suiterc_arg',
-    [pytest.param(False, id="symlink_suiterc=False "),
-     pytest.param(True, id="symlink_suiterc=True ")]
-)
-def test_check_flow_file_symlink(
-    flow_file_target: Optional[str],
-    suiterc_exists: bool,
-    err: Optional[Type[Exception]],
-    expected_file: Optional[str],
-    symlink_suiterc_arg: bool,
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """Test check_flow_file() when flow.cylc is a symlink or doesn't exist.
-
-    Params:
-        flow_file_target: Relative path of the flow.cylc symlink's target, or
-            None if the symlink doesn't exist.
-        suiterc_exists: Whether there is a suite.rc file in the dir.
-        err: Type of exception if expected to get raised.
-        expected_file: Which file's path should get returned, when
-            symlink_suiterc_arg is FALSE (otherwise it will always be
-            flow.cylc, assuming no exception occurred).
-        symlink_suiterc_arg: Value of the symlink_suiterc arg passed to
-            check_flow_file().
-    """
-    flow_file = tmp_path.joinpath(WorkflowFiles.FLOW_FILE)
-    suiterc = tmp_path.joinpath(WorkflowFiles.SUITE_RC)
-    tmp_path.joinpath('other-path').touch()
-    if suiterc_exists:
-        suiterc.touch()
-    if flow_file_target:
-        flow_file.symlink_to(flow_file_target)
-
-    caplog.set_level(logging.INFO, CYLC_LOG)
-    log_msg = ""
-
-    if err:
-        with pytest.raises(err):
-            check_flow_file(tmp_path, symlink_suiterc_arg)
-    else:
-        assert expected_file is not None  # otherwise test is wrong
-        result = check_flow_file(tmp_path, symlink_suiterc_arg)
-        if symlink_suiterc_arg is True:
-            assert flow_file.samefile(suiterc)
-            expected_file = WorkflowFiles.FLOW_FILE
-            if flow_file_target != WorkflowFiles.SUITE_RC:
-                log_msg = "Symlink created: flow.cylc -> suite.rc"
-        assert result == tmp_path.joinpath(expected_file)
-
-    if log_msg:
-        assert log_msg in caplog.messages
-
-
 def test_detect_both_flow_and_suite_symlinked(tmp_path):
     """Test flow.cylc symlinked to suite.rc together in dir is permitted."""
     (tmp_path / WorkflowFiles.SUITE_RC).touch()
@@ -1935,6 +1852,8 @@ def test_flow_symlinked_elsewhere_and_suite_present(tmp_path: Path):
     run_dir.mkdir(exist_ok=True)
     flow_file = (run_dir / WorkflowFiles.FLOW_FILE)
     flow_file.symlink_to(suite_file)
+    forbidden_external = is_forbidden(flow_file)
+    assert forbidden_external is False
     (run_dir / WorkflowFiles.SUITE_RC).touch()
     forbidden = is_forbidden(flow_file)
     assert forbidden is True
@@ -1951,7 +1870,6 @@ def test_flow_symlinked_elsewhere_and_suite_present(tmp_path: Path):
 
 def test_is_forbidden_symlink_returns_false_for_non_symlink(tmp_path):
     """Test sending a non symlink path is not marked as forbidden"""
-    Path(tmp_path)
     flow_file = (tmp_path / WorkflowFiles.FLOW_FILE)
     flow_file.touch()
     forbidden = is_forbidden(Path(flow_file))

From a49283c68af4cd2f3f02f8eba24a71e53f46ba45 Mon Sep 17 00:00:00 2001
From: Melanie Hall <37735232+datamel@users.noreply.github.com>
Date: Tue, 30 Nov 2021 09:53:43 +0000
Subject: [PATCH 07/11] Update tests/unit/test_workflow_files.py

Co-authored-by: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>
---
 tests/unit/test_workflow_files.py | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/tests/unit/test_workflow_files.py b/tests/unit/test_workflow_files.py
index 14ebe659bc1..8bd87fcb41f 100644
--- a/tests/unit/test_workflow_files.py
+++ b/tests/unit/test_workflow_files.py
@@ -1859,13 +1859,10 @@ def test_flow_symlinked_elsewhere_and_suite_present(tmp_path: Path):
     assert forbidden is True
     with pytest.raises(WorkflowFilesError) as exc:
         detect_both_flow_and_suite(run_dir)
-        assert str(exc.value) == (
-            "Both flow.cylc and suite.rc files are present in the "
-            "source directory. Please remove one and try again. "
-            "For more information visit: "
-            "https://cylc.github.io/cylc-doc/latest/html/7-to-8/summary.html"
-            "#backward-compatibility"
-        )
+    assert str(exc.value).startswith(
+        "Both flow.cylc and suite.rc files are present in the "
+        "source directory. Please remove one and try again."
+    )
 
 
 def test_is_forbidden_symlink_returns_false_for_non_symlink(tmp_path):

From 90f2693bb61eb1d51737d00b0edbc6f8b3e03c2f Mon Sep 17 00:00:00 2001
From: Mel Hall <37735232+datamel@users.noreply.github.com>
Date: Tue, 30 Nov 2021 12:54:48 +0000
Subject: [PATCH 08/11] dedent test

---
 tests/unit/test_workflow_files.py | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/tests/unit/test_workflow_files.py b/tests/unit/test_workflow_files.py
index 14ebe659bc1..db4c8719a0f 100644
--- a/tests/unit/test_workflow_files.py
+++ b/tests/unit/test_workflow_files.py
@@ -1826,13 +1826,12 @@ def test_detect_both_flow_and_suite(tmp_path):
     assert forbidden is True
     with pytest.raises(WorkflowFilesError) as exc:
         detect_both_flow_and_suite(tmp_path)
-        assert str(exc.value) == (
-            "Both flow.cylc and suite.rc files are present in the "
-            "source directory. Please remove one and try again. "
-            "For more information visit: "
-            "https://cylc.github.io/cylc-doc/latest/html/7-to-8/summary.html"
-            "#backward-compatibility"
-        )
+    assert str(exc.value) == (
+        f"Both flow.cylc and suite.rc files are present in {tmp_path}. Please "
+        "remove one and try again. For more information visit: "
+        "https://cylc.github.io/cylc-doc/latest/html/7-to-8/"
+        "summary.html#backward-compatibility"
+    )
 
 
 def test_detect_both_flow_and_suite_symlinked(tmp_path):

From 97fab793f78055b58dcf36e3122e25c93e05b85f Mon Sep 17 00:00:00 2001
From: Mel Hall <37735232+datamel@users.noreply.github.com>
Date: Tue, 30 Nov 2021 13:18:10 +0000
Subject: [PATCH 09/11] Fix test

---
 tests/unit/test_workflow_files.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/unit/test_workflow_files.py b/tests/unit/test_workflow_files.py
index f0936fe53f1..cdcc5e32fb1 100644
--- a/tests/unit/test_workflow_files.py
+++ b/tests/unit/test_workflow_files.py
@@ -1859,8 +1859,8 @@ def test_flow_symlinked_elsewhere_and_suite_present(tmp_path: Path):
     with pytest.raises(WorkflowFilesError) as exc:
         detect_both_flow_and_suite(run_dir)
     assert str(exc.value).startswith(
-        "Both flow.cylc and suite.rc files are present in the "
-        "source directory. Please remove one and try again."
+        "Both flow.cylc and suite.rc files are present in "
+        f"{run_dir}. Please remove one and try again."
     )
 
 

From 6e4895c225b6f60f7805012a82ff12ee07712477 Mon Sep 17 00:00:00 2001
From: Tim Pillinger <26465611+wxtim@users.noreply.github.com>
Date: Thu, 2 Dec 2021 09:53:15 +0000
Subject: [PATCH 10/11] Update cylc/flow/workflow_files.py

Co-authored-by: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>
---
 cylc/flow/workflow_files.py | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/cylc/flow/workflow_files.py b/cylc/flow/workflow_files.py
index b5e92959b93..0a831a21a02 100644
--- a/cylc/flow/workflow_files.py
+++ b/cylc/flow/workflow_files.py
@@ -1790,13 +1790,10 @@ def is_forbidden(flow_file: Path) -> bool:
             return True
         return False
     link = flow_file.resolve()
-    if link.parent == flow_file.parent:
-        # link points within dir (permitted)
-        return False
-    # link points elsewhere, check that suite.rc does not also exist in dir
-    if flow_file.parent.joinpath(WorkflowFiles.SUITE_RC).exists():
-        return True
-    return False
+    suite_rc = flow_file.parent / WorkflowFiles.SUITE_RC
+    if suite_rc.exists():
+        return link != suite_rc
+    return True
 
 
 def detect_flow_exists(

From 5484cb6aa4e01fd922ebf2aafa921f870f115fb3 Mon Sep 17 00:00:00 2001
From: Mel Hall <37735232+datamel@users.noreply.github.com>
Date: Thu, 2 Dec 2021 11:16:11 +0000
Subject: [PATCH 11/11] Change logic comparing symlinked flow.cylc file.

---
 cylc/flow/workflow_files.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/cylc/flow/workflow_files.py b/cylc/flow/workflow_files.py
index b5e92959b93..a31b91ee7b4 100644
--- a/cylc/flow/workflow_files.py
+++ b/cylc/flow/workflow_files.py
@@ -1790,8 +1790,8 @@ def is_forbidden(flow_file: Path) -> bool:
             return True
         return False
     link = flow_file.resolve()
-    if link.parent == flow_file.parent:
-        # link points within dir (permitted)
+    if link == flow_file.parent.resolve() / WorkflowFiles.SUITE_RC:
+        # link points within dir to suite.rc (permitted)
         return False
     # link points elsewhere, check that suite.rc does not also exist in dir
     if flow_file.parent.joinpath(WorkflowFiles.SUITE_RC).exists():