Cannot `cmake` a Qt project from a subshell when using the Yocto toolchain

I have a project whose configuration steps are as follows:

cmake /src

This is being built in an Ubuntu 20.04 docker container where the only contents are the Yocto toolchain for my image and last line of $HOME/.bashrc is source /opt/my-distro/2.5.3/environment-setup-aarch64-poky-linux

If I load up the docker container as follows...

  (host) $ docker run --rm -it -v /home/me/my-source:/src mybuildenv:latest
(docker) $ mkdir /build
(docker) $ cd /build
(docker) $ cmake /src
-- The CXX compiler identification is GNU 7.3.0
-- Check for working CXX compiler: /opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-g++
-- Check for working CXX compiler: /opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-g++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /build

If I load up the container and do the same cmake command in a subshell, I get

  (host) $ docker run --rm -it -v /home/me/my-source:/src mybuildenv:latest
(docker) $ mkdir /build
(docker) $ cd /build
(docker) $ /bin/bash -c 'cmake /src'
-- The CXX compiler identification is GNU 7.3.0
-- Check for working CXX compiler: /opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-g++
-- Check for working CXX compiler: /opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-g++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at application/CMakeLists.txt:17 (find_package):
  By not providing "FindQt5.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Qt5", but
  CMake did not find one.

  Could not find a package configuration file provided by "Qt5" with any of
  the following names:

    Qt5Config.cmake
    qt5-config.cmake

  Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
  to a directory containing one of the above files.  If "Qt5" provides a
  separate development package or SDK, be sure it has been installed.


-- Configuring incomplete, errors occurred!
See also "/build/CMakeFiles/CMakeOutput.log".

I expect this to work since both the parent and subshells environments...

(docker) $ env
...
(docker) $ /bin/bash -c 'env'
...

... are functionally identical (ordering slightly different but all variables are the exact same).

I am unsure where the problems lies, if it's in bash, docker, cmake, or yocto. This is a problem since the Microsoft Azure pipeline I am running this build environment in is spawning a sub shell under docker exec and under this circumstance I cannot built my application.

EDIT

One other thing I looked at was the variables define in the CMake files using this snippet:

get_cmake_property(_variableNames VARIABLES)
list (SORT _variableNames)
foreach (_variableName ${_variableNames})
    message(STATUS "${_variableName}=${${_variableName}}")
endforeach()

The diff:

< -- CMAKE_AR=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-ar
< -- CMAKE_AR=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-ar
< -- CMAKE_ASM_FLAGS= -O2 -pipe -g -feliminate-unused-debug-types
---
> -- CMAKE_AR=/usr/bin/ar
> -- CMAKE_AR=/usr/bin/ar
18c17
< -- CMAKE_CROSSCOMPILING=TRUE
---
> -- CMAKE_CROSSCOMPILING=FALSE
39c38
< -- CMAKE_CXX_ARCHIVE_APPEND_IPO="/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gcc-ar" r <TARGET> <LINK_FLAGS> <OBJECTS>
---
> -- CMAKE_CXX_ARCHIVE_APPEND_IPO="/usr/bin/gcc-ar" r <TARGET> <LINK_FLAGS> <OBJECTS>
41c40
< -- CMAKE_CXX_ARCHIVE_CREATE_IPO="/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gcc-ar" cr <TARGET> <LINK_FLAGS> <OBJECTS>
---
> -- CMAKE_CXX_ARCHIVE_CREATE_IPO="/usr/bin/gcc-ar" cr <TARGET> <LINK_FLAGS> <OBJECTS>
43c42
< -- CMAKE_CXX_ARCHIVE_FINISH_IPO="/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gcc-ranlib" <TARGET>
---
> -- CMAKE_CXX_ARCHIVE_FINISH_IPO="/usr/bin/gcc-ranlib" <TARGET>
48,49c47,48
< -- CMAKE_CXX_COMPILER_AR=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gcc-ar
< -- CMAKE_CXX_COMPILER_AR=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gcc-ar
---
> -- CMAKE_CXX_COMPILER_AR=/usr/bin/gcc-ar
> -- CMAKE_CXX_COMPILER_AR=/usr/bin/gcc-ar
315,316c314,315
< -- CMAKE_CXX_COMPILER_RANLIB=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gcc-ranlib
< -- CMAKE_CXX_COMPILER_RANLIB=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gcc-ranlib
---
> -- CMAKE_CXX_COMPILER_RANLIB=/usr/bin/gcc-ranlib
> -- CMAKE_CXX_COMPILER_RANLIB=/usr/bin/gcc-ranlib
333c332
< -- CMAKE_CXX_FLAGS= -O2 -pipe -g -feliminate-unused-debug-types
---
> -- CMAKE_CXX_FLAGS=-O2 -pipe -g -feliminate-unused-debug-types
366d364
< -- CMAKE_C_FLAGS= -O2 -pipe -g -feliminate-unused-debug-types
396,400d393
< -- CMAKE_FIND_ROOT_PATH=/opt/my-distro/2.5.3/sysroots/aarch64-poky-linux;/opt/b9-core-5/2.5.3/sysroots/x86_64-pokysdk-linux
< -- CMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY
< -- CMAKE_FIND_ROOT_PATH_MODE_LIBRARY=ONLY
< -- CMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ONLY
< -- CMAKE_FIND_ROOT_PATH_MODE_PROGRAM=NEVER
419d411
< -- CMAKE_LDFLAGS_FLAGS= -O2 -pipe -g -feliminate-unused-debug-types
423,424c415,416
< -- CMAKE_LINKER=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-ld
< -- CMAKE_LINKER=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-ld
---
> -- CMAKE_LINKER=/usr/bin/ld
> -- CMAKE_LINKER=/usr/bin/ld
444,446c436,438
< -- CMAKE_NM=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-nm
< -- CMAKE_OBJCOPY=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-objcopy
< -- CMAKE_OBJDUMP=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-objdump
---
> -- CMAKE_NM=/usr/bin/nm
> -- CMAKE_OBJCOPY=/usr/bin/objcopy
> -- CMAKE_OBJDUMP=/usr/bin/objdump
454,455c446,447
< -- CMAKE_RANLIB=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-ranlib
< -- CMAKE_RANLIB=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-ranlib
---
> -- CMAKE_RANLIB=/usr/bin/ranlib
> -- CMAKE_RANLIB=/usr/bin/ranlib
511,512c503,504
< -- CMAKE_STRIP=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-strip
< -- CMAKE_SYSTEM=Linux
---
> -- CMAKE_STRIP=/usr/bin/strip
> -- CMAKE_SYSTEM=Linux-5.15.0-56-generic
519c511
< -- CMAKE_SYSTEM_PROCESSOR=aarch64
---
> -- CMAKE_SYSTEM_PROCESSOR=x86_64
522,523c514
< -- CMAKE_SYSTEM_VERSION=
< -- CMAKE_TOOLCHAIN_FILE=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/share/cmake/OEToolchainConfig.cmake
---
> -- CMAKE_SYSTEM_VERSION=5.15.0-56-generic
528d518
< -- COMPILER_BASENAME=aarch64-poky-linux-g++
531d520
< -- INCLUDE_CMAKE_TOOLCHAIN_FILE_IF_REQUIRED=include("/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/share/cmake/OEToolchainConfig.cmake")
533,534c522
< -- OE_QMAKE_PATH_EXTERNAL_HOST_BINS=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/bin
< -- PRESET_CMAKE_SYSTEM_NAME=TRUE
---
> -- PRESET_CMAKE_SYSTEM_NAME=FALSE
549d536
< -- _CMAKE_TOOLCHAIN_PREFIX=aarch64-poky-linux-
552d538
< -- _INCLUDED_TOOLCHAIN_FILE=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/share/cmake/OEToolchainConfig.cmake
564d549
< -- config=
575d559
< -- toolchain_config_files=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/share/cmake/OEToolchainConfig.cmake.d/OEQt5Toolchain.cmake

So, as seen when I run /bin/bash -c "cmake /src" no toolchain related variables are populated, while when I run cmake /src there are. Is there any reason this would be the case when the bash environments are the same? Is there something I can do to make sure the variables carry over? I don't seem to have this problem with qmake.

Solution

The reason /bin/bash -c "cmake /src" is not equivalent to cmake /src is because cmake was an alias for cmake -DCMAKE_TOOLCHAIN_FILE=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/share/cmake/OEToolchainConfig.cmake and aliases are not inherited by subshells.

The solution is to use /bin/bash -c "cmake -DCMAKE_TOOLCHAIN_FILE=/opt/my-distro/2.5.3/sysroots/x86_64-pokysdk-linux/usr/share/cmake/OEToolchainConfig.cmake'"