Bitbake build of simple source file not generating object file unless I set the -f (forced) flag option - yocto

Question

Let me just say that I am new to Yocto. I have been able to create recipes, packages, images etc. however I am encountering the following issue. Using online references of which there are many, I have tried to create and build a simple Yocto 'helloworld' recipe using bitbake, which has the following structure:
├── conf
│ └── layer.conf
├── COPYING.MIT
├── README
└── recipes-example
├── example
│ └── example_0.1.bb
└── helloworld
├── files
│ └── hellopeterworld.c
└── helloworld_0.1.bb
The content of the hellopeterworld.c source file is as follows:
#include <stdio.h>
int main() {
printf("Hello, C Programming World! This is Peter!");
return 0;
}
The content of the helloworld_0.1.bb recipe is as follows:
SUMMARY = "bitbake-layers recipe"
DESCRIPTION = "A friendly program that prints Hello World!"
PRIORITY = "optional"
SECTION = "examples"
LICENSE = "MIT"
LIC_FILES_CHKSUM = file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302
SRC_URI = file://hellopeterworld.c
S = "${WORKDIR}"
do_compile() {
${CC} ${CFLAGS} ${LDFLAGS} hellopeterworld.c -o hellopeterworld
}
do_install() {
install -d ${D}${bindir}
install -m 0755 hellopeterworld ${D}${bindir}
}
When attempting to build the recipe, say, the build output in the folder:
/tmp-glibc/work/cortexa7t2hf-neon-vfpv4-ostl-linux-gnueabi/helloworld/0.1-r0/
is as follows:
-rw-r—r—1 pgroves pgroves 65 Feb 23 10:45 configure.sstate
drwxr-xr-x 3 pgroves pgroves 4096 Feb 23 10:20 deploy-debs
-rwxr-xr-x 1 pgroves pgroves 13512 Feb 23 10:45 hellopeterworld
-rw-rw-r—1 pgroves pgroves 101 Feb 23 10:15 hellopeterworld.c
drwxr-xr-x 3 pgroves pgroves 4096 Feb 23 10:45 image
drwxr-xr-x 2 pgroves pgroves 4096 Feb 23 10:45 patches
drwxrwxr-x 2 pgroves pgroves 4096 Feb 23 10:45 pseudo
drwxrwxr-x 5 pgroves pgroves 4096 Feb 23 10:45 recipe-sysroot
drwxrwxr-x 7 pgroves pgroves 4096 Feb 23 10:45 recipe-sysroot-native
drwxr-xr-x 2 pgroves pgroves 4096 Feb 23 10:45 source-date-epoch
drwxrwxr-x 2 pgroves pgroves 4096 Feb 23 10:55 sstate-install-package_write_deb
drwxrwxr-x 2 pgroves pgroves 20480 Feb 23 10:55 temp
The problem is that the ‘hellopeterworld’ object is not always being generated on subsequent 'bitbake helloworld' builds. Running a bitbake -c clean helloworld removes the contents of '0.1-r0' directory. The contents is restored only if I force the build using bitbake -f -c compile helloworld but this has a side effect with the following WARNING being raised:
'helloworld_0.1.bb:do_compile is tainted from a forced run'.
The funny thing is that if I edit the source file and add a deliberate bad syntax change, the rebuild detects the bad syntax and generates an error, as expected:
NOTE: Executing Tasks
ERROR: helloworld-0.1-r0 do_compile: Execution of
'<my_workspace>/build-
openstlinuxweston-stm32mp13-disco/tmp-glibc/work/cortexa7t2hf-neon-vfpv4-ostl-linux-
gnueabi/helloworld/0.1-r0/temp/run.do_compile.83597' failed with exit code 1:
hellopeterworld.c: In function 'main':
hellopeterworld.c:4:1: error: expected expression before '?' token
4 | ? printf("Hello, C Programming World! This is Peter!");
| ^
But if I then re-edit and fix the file and rebuild, the build completes but the the object file still isn’t being regenerated. I'm seeing the same thing with more complex examples.
Does anyone know the reason for this? Am I missing something here?

Answer 1

First of all, it is weird why it didn't fail because of a syntax error in variables SRC_URI and LIC_FILES_CHKSUM, they need to be in ".
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
SRC_URI = "file://hellopeterworld.c"
I have tested your recipe and the build restarts automatically when I change the hellopeterworld.c file in the recipe folder.
However, when you run do_clean it does not remove the sstate object of the recipe, it only removes the build output, so when you rerun again it will do nothing.
In order to clean the sstate object you need to run do_cleansstate.
Other than that, I do not see any issue with your recipe.