Export-pkg assumes only package() method modifies package_directory

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Conan version: 1.0.2

Issue

When using conan export-pkg to export a package, conan assumes the recipe’s package() method is all that needs to be invoked.

As per the guide, cmake-projects can use the helper cmake.install() in their build() method, if targets are already setup for installation in CMake.

Steps to reproduce

Given the following conanfile:

class TestpkgConan(ConanFile):
    name = "testpkg"
    version = "0.1"
    generators = "cmake"
    exports_sources = "src/*"

    def build(self):
        # Doing a copy here to simluate cmake.install()
        self.run("mkdir -p package/share && cp src/CMakeLists.txt package/share/")

    def package(self):
        # Noop
        return

And the following shell session:

λ conan build .
...
λ conan package .
PROJECT: Generating the package
PROJECT: Package folder testpkg/package
PROJECT: Calling package()
PROJECT package(): WARN: No files copied!
PROJECT: Package 'package' created
λ conan export-pkg . testpkg/0.1@sheeo/testing
testpkg/0.1@sheeo/testing export: Copied 1 '.h' files: hello.h
testpkg/0.1@sheeo/testing export: Copied 1 '.cpp' files: hello.cpp
testpkg/0.1@sheeo/testing export: Copied 1 '.txt' files: CMakeLists.txt
Packaging to 5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
λ conan export-pkg -f . testpkg/0.1@sheeo/testing
...
testpkg/0.1@sheeo/testing: Calling package()
testpkg/0.1@sheeo/testing package(): WARN: No files copied!
testpkg/0.1@sheeo/testing: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' created

It should be expected that the package folder contains the CMakeLists.txt file copied in the build() step, however, only the following files are present:

λ ls -la ~/.conan/data/testpkg/0.1/sheeo/testing/package/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
total 16
-rw-r--r--  1 sheeo  staff   150B Jan 22 13:49 conaninfo.txt
-rw-r--r--  1 sheeo  staff    59B Jan 22 13:49 conanmanifest.txt

[Sheeo]

Yep, that’d be sufficient 👍

[danimtb]

@bryceschober there is a proposed PR in the docs to update that section conan-io/docs#750 too