[bug] Dependencies' build_policy overwrites command line parameter

We recently encountered an issue with our CI system, when incorrectly configured dependency packages were rebuilt in a CI step, where we didn’t allow it via --build=never.

Environment Details

• Operating System+version: Windows 10
• Conan version: 1.22.0 and 1.23.0
• Python version: 3.6.4

Steps to reproduce

a/conanfile.py

from conans import ConanFile

class TestA(ConanFile):
  name = "TestA"
  version = "1.0"
  requires = "TestB/1.0@test/test"

  def build(self):
    self.output.info("Build TestA")

b/conanfile.py

from conans import ConanFile

class TestB(ConanFile):
  name = "TestB"
  version = "1.0"
  build_policy = "missing" # !!!

  def build(self):
    self.output.info("Build TestB")

1. Create packages TestA and TestB

   conan create b test/test
   conan create a test/test
   

2. Remove package TestB and reexport the conanfile

   conan remove TestB
   conan export b test/test
   

3. Install TestA without build

   conan install TestA/1.0@test/test --build=never
   

Expected behavior:

Install command should fail, since TestB is not installed and --build=never is specified.

Actual behavior:

Install command succeeds and TestB is rebuilt (see log).

Remark: The same bug occurs when setting build_policy=always in b/conanfile.py. You can then skip step 2 and specify --build=missing in step 3, then TestB will be rebuilt although it shouldn’t.

Logs

Log for step 3:

PS E:\Workspace\conan_bug> conan install TestA/1.0@test/test --build=never
Configuration:
[settings]
arch=x86_64
arch_build=x86_64
build_type=Release
compiler=Visual Studio
compiler.runtime=MD
compiler.version=15
os=Windows
os_build=Windows
[options]
[build_requires]
[env]

TestB/1.0@test/test: Building package from source as defined by build_policy='missing'
Installing package: TestA/1.0@test/test
Requirements
    TestA/1.0@test/test from local cache - Cache
    TestB/1.0@test/test from local cache - Cache
Packages
    TestA/1.0@test/test:5c07eea89709163d6f80759ede846381d3745442 - Cache
    TestB/1.0@test/test:5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9 - Build

Installing (downloading, building) binaries...
TestB/1.0@test/test: Configuring sources in C:\Users\Oliver\.conan\data\TestB\1.0\test\test\source
TestB/1.0@test/test: Copying sources to build folder
TestB/1.0@test/test: Building your package in C:\Users\Oliver\.conan\data\TestB\1.0\test\test\build\5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
TestB/1.0@test/test: Generator txt created conanbuildinfo.txt
TestB/1.0@test/test: Calling build()
TestB/1.0@test/test: Build TestB
TestB/1.0@test/test: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' built
TestB/1.0@test/test: Build folder C:\Users\Oliver\.conan\data\TestB\1.0\test\test\build\5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
TestB/1.0@test/test: Generated conaninfo.txt
TestB/1.0@test/test: Generated conanbuildinfo.txt
TestB/1.0@test/test: Generating the package
TestB/1.0@test/test: Package folder C:\Users\Oliver\.conan\data\TestB\1.0\test\test\package\5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
TestB/1.0@test/test: Calling package()
TestB/1.0@test/test: WARN: This conanfile has no package step
TestB/1.0@test/test package(): WARN: No files in this package!
TestB/1.0@test/test: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' created
TestB/1.0@test/test: Created package revision 4d0ed6b951018d8af295b25c8922813c
TestA/1.0@test/test: Already installed!

[memsharded]

Hi, are you intending to keep this behavior for Conan 2.0?

We are considering removing these policies for Conan 2.0, or at least redefine their behavior.

The use cases are for example: a driver, that needs to be built from sources always in the target machine. Only the recipe is uploaded, but it is a bit annoying to always fail when users do install them (maybe even transitively, they are not aware of this driver). Having it in the profile is still on the consumer side, they will still fail, realize they need to build that, add it to their profiles, so a bit inconvenient too. But might be more explicit, and then more aligned with general conan design.

Lets annotate this for Conan 2.0 review.

[czoido]

Closed by https://github.com/conan-io/conan/pull/12751 will be in beta7