[OE-core] [PATCH 1/1] add checking to standardize how .bbappend files do FILESEXTRAPATHS

[Hongxu Jia]

When adding patches or config files from bbappend files, it requires
the use of FILESEXTRAPATHS, which has been an issue and failure point
for people starting to work with bitbake and oe-core.

We add checking to standardize how to use FILESEXTRAPATHS. Only the
format of:
  FILESEXTRAPATHS_append := ${THISDIR}/Your_Files_Path or
  FILESEXTRAPATHS_prepend := ${THISDIR}/Your_Files_Path
is acceptable.

[YOCTO #5412]

Signed-off-by: Hongxu Jia <hongxu.jia at windriver.com>
---
 meta/classes/base.bbclass                  |  1 +
 meta/classes/filesextrapaths_check.bbclass | 10 ++++++++++
 meta/classes/utils.bbclass                 |  2 ++
 meta/conf/bitbake.conf                     |  2 ++
 4 files changed, 15 insertions(+)
 create mode 100644 meta/classes/filesextrapaths_check.bbclass

diff --git a/meta/classes/base.bbclass b/meta/classes/base.bbclass
index 8114cf6..be8400a 100644
--- a/meta/classes/base.bbclass
+++ b/meta/classes/base.bbclass
@@ -9,6 +9,7 @@ inherit utils
 inherit utility-tasks
 inherit metadata_scm
 inherit logging
+inherit filesextrapaths_check
 
 OE_IMPORTS += "os sys time oe.path oe.utils oe.data oe.package oe.packagegroup oe.sstatesig oe.lsb oe.cachedpath"
 OE_IMPORTS[type] = "list"
diff --git a/meta/classes/filesextrapaths_check.bbclass b/meta/classes/filesextrapaths_check.bbclass
new file mode 100644
index 0000000..6863e0c
--- /dev/null
+++ b/meta/classes/filesextrapaths_check.bbclass
@@ -0,0 +1,10 @@
+python __anonymous() {
+    # Checking ${FILESEXTRAPATHS}
+    extrapaths = (d.getVar("FILESEXTRAPATHS", True) or "")
+    if '__default' not in extrapaths.split(":"):
+        msg =  "Please assign FILESEXTRAPATHS with the format of:\n"
+        msg += "  FILESEXTRAPATHS_append := ${THISDIR}/Your_Files_Path or\n"
+        msg += "  FILESEXTRAPATHS_prepend := ${THISDIR}/Your_Files_Path\n"
+        msg += "in your bbappend file\n"
+        bb.fatal(msg)
+}
diff --git a/meta/classes/utils.bbclass b/meta/classes/utils.bbclass
index 0ee13e0..0f2a484 100644
--- a/meta/classes/utils.bbclass
+++ b/meta/classes/utils.bbclass
@@ -312,6 +312,8 @@ def explode_deps(s):
 def base_set_filespath(path, d):
     filespath = []
     extrapaths = (d.getVar("FILESEXTRAPATHS", True) or "")
+    # Remove default flag which was used for checking
+    extrapaths = extrapaths.replace("__default:", "")
     # Don't prepend empty strings to the path list
     if extrapaths != "":
         path = extrapaths.split(":") + path
diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
index f4870d5..6a0cf7a 100644
--- a/meta/conf/bitbake.conf
+++ b/meta/conf/bitbake.conf
@@ -311,6 +311,8 @@ FILES_${PN}-locale = "${datadir}/locale"
 FILE_DIRNAME = "${@os.path.dirname(d.getVar('FILE'))}"
 # FILESPATH is set in base.bbclass
 #FILESPATH = "${FILE_DIRNAME}/${PF}:${FILE_DIRNAME}/${P}:${FILE_DIRNAME}/${PN}:${FILE_DIRNAME}/${BP}:${FILE_DIRNAME}/${BPN}:${FILE_DIRNAME}/files:${FILE_DIRNAME}"
+# This default was only used for checking
+FILESEXTRAPATHS ?= "__default:"
 
 ##################################################################
 # General work and output directories for the build system.
-- 
1.8.1.2