E3-944: Warn if building from install path

If a user runs the build from the E3_SITEMODS_PATH, then it can happen that
false dependencies get registered due to how the generated .d files are
parsed to determine module dependencies. Specifically, if you have header
file being used that is located at

${E3_SITEMODS_PATH}/e3-module/module/src/header.h

and it is _not_ being installed, then the dependency parsing script will
see a dependency as an absolute path, and so register that your module
depends on the module `e3-module` version `module`, which is obviously
not what was intended.

While we don't want to stricly _prevent_ a user from building there, it
seems wise to _warn_ a user that there may be unintended consequences.

configure/E3/RULES_CHECKS

@@ -2,7 +2,7 @@
 consistency_checks: module_name_check loc-check
 
 ifneq (require,$(E3_MODULE_NAME))
-consistency_checks: sitemods_check
+consistency_checks: sitemods_check build_path_check
 endif
 
 # Check that the module name satisfies a few conditions before we go on.
@@ -19,8 +19,13 @@ ifeq ($(filter RULES_SITEMODS,$(notdir $(MAKEFILE_LIST))),)
 endif
 
 # Check that e3 wrappers are using EPICS_MODULE_TAG to manage local source mode
-.PHONU: loc-check
+.PHONY: loc-check
 loc-check:
 ifneq (,$(findstring -loc,$(E3_MODULE_SRC_PATH)))
 	$(error DEPRECATED: Local source mode "-loc" has been deprecated. Please comment out the EPICS_MODULE_TAG to use local source mode.)
 endif
+
+.PHONY: build_path_check
+build_path_check:
+	$(if $(filter $(abspath $(E3_MODULES_PATH))/%,$(abspath $(TOP))),$(warning It is ill-advised to build a module from the module install location.)\
+	$(warning Please note that you may obtain unexpected results.))

tests/conftest.py

@@ -109,6 +109,7 @@ EXCLUDE_ARCHS+=debug
         *args,
         module_version: str = "",
         cell_path: str = "",
+        **kwargs,
     ):
         """Attempt to run `make <target> <args>` for the current wrapper."""
 
@@ -119,6 +120,9 @@ EXCLUDE_ARCHS+=debug
         if target == "uninstall":
             target = "celluninstall"
 
+        env = os.environ.copy()
+        env.update(kwargs)
+
         args = list(args)
         if module_version:
             args.append(f"E3_MODULE_VERSION={module_version}")
@@ -130,6 +134,7 @@ EXCLUDE_ARCHS+=debug
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
             encoding="utf-8",
+            env=env,
         )
         outs, errs = p.communicate()
         return p.returncode, outs, errs

tests/test_e3.py

@@ -39,3 +39,13 @@ def test_add_missing_build_number(wrapper: Wrapper):
     rc, outs, _ = wrapper.run_make("vars")
     assert rc == 0
     assert f"E3_MODULE_VERSION = {version}+0" in outs.splitlines()
+
+
+def test_warning_if_building_from_sitemods(wrapper: Wrapper):
+    rc, _, errs = wrapper.run_make(
+        "build_path_check", E3_MODULES_PATH=wrapper.path / ".."
+    )
+    assert rc == 0
+    assert (
+        "It is ill-advised to build a module from the module install location." in errs
+    )