Release 1.41 blogpost

_posts/2021-10-14-New-conan-release-1-41.markdown

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+---
+layout: post
+comments: false
+title: "Conan 1.41: Better support for layout() local flows and editables, IntelOneAPI support, environment multi-config support, new cpp_info.objects model (and CMakeDeps support), support multiple toolchains in one recipe."
+meta_title: "Version 1.41 of Conan C++ Package Manager is Released"
+meta_description: "The new version features includes better support for layout() local flows and editables, IntelOneAPI support, environment multi-config support, cpp_info.objects model (and CMakeDeps support), support multiple toolchains in one recipe and much more..."
+---
+
+<script type="application/ld+json">
+{ "@context": "https://schema.org", 
+ "@type": "TechArticle",
+ "headline": "Version 1.41 of Conan C++ Package Manager is Released",
+ "alternativeHeadline": "Learn all about the new 1.41 Conan C/C++ package manager version",
+ "image": "https://docs.conan.io/en/latest/_images/frogarian.png",
+ "author": "Conan Team", 
+ "genre": "C/C++", 
+ "keywords": "c c++ package manager conan release", 
+ "publisher": {
+    "@type": "Organization",
+    "name": "Conan.io",
+    "logo": {
+      "@type": "ImageObject",
+      "url": "https://media.jfrog.com/wp-content/uploads/2017/07/20134853/conan-logo-text.svg"
+    }
+},
+ "datePublished": "2021-10-14",
+ "description": "Better support for layout() local flows and editables, IntelOneAPI support, environment multi-config support, cpp_info.objects model (and CMakeDeps support), support multiple toolchains in one recipe.",
+ }
+</script>
+
+We are pleased to announce that [Conan 1.41 is
+out](https://github.com/conan-io/conan/releases/tag/1.41.0) and comes with some significant new
+features and bug fixes. Local flows and [editable
+packages](https://docs.conan.io/en/latest/developing_packages/editable_packages.html) are now easier
+to handle using [layout()](https://docs.conan.io/en/latest/reference/conanfile/tools/layout.html).
+We introduced support for [Intel's oneAPI Toolkits](https://www.oneapi.io/) with a new
+`intel-cc` compiler setting. Also, the new environment supports multi-configuration generators now.
+We have added a new `objects` attribute in the conanfile's
+[cpp_info](https://docs.conan.io/en/latest/reference/conanfile/attributes.html#cpp-info) to provide
+object files (_.obj_ and _.o_) with which consumers can link. Finally, from  this version, it's
+possible to use multiple different toolchains like
+[AutotoolsToolchain](https://docs.conan.io/en/latest/reference/conanfile/tools/gnu/autotoolstoolchain.html),
+[BazelToolchain](https://docs.conan.io/en/latest/reference/conanfile/tools/google.html#bazeltoolchain),
+and
+[CMakeToolchain](https://docs.conan.io/en/latest/reference/conanfile/tools/cmake/cmaketoolchain.html)
+in the same recipe.
+
+## Easier local flows and editable packages handling using layout()
+
+For this release, we have fixed some issues regarding the new
+[layout()](https://blog.conan.io/2021/06/10/New-conan-release-1-37.html) feature introduced in Conan
+1.37. This feature makes it easier to work with packages in [editable
+mode](https://docs.conan.io/en/latest/developing_packages/editable_packages.html) and use the [local
+development flow](https://docs.conan.io/en/latest/developing_packages/package_dev_flow.html). When a
+package is in editable mode, Conan looks for its contents in the local work folder instead of the
+Conan local cache. That way, you can rebuild your package locally so the packages that depend on this editable
+package will link with the updated package without needing a ``conan create`` command for each change
+in the sources.
+
+Let's suppose you are developing a package called `say` using CMake and you have this project structure:
+
+```
+.
+├── conanfile.py
+└── say_sources
+    ├── CMakeLists.txt
+    ├── cpp
+    │   └── say.cpp
+    └── hpp
+        └── say.h
+```
+
+Using the `layout()` feature, we can describe the package contents so consumers of this package can
+find it no matter if we are working in “regular” (find contents in Conan cache) or editable mode
+(find contents in local working folder). Let's see how we set those values in the `layout()` method
+so that the `say` package is found in both cases. The conanfile of this package could look like this:
+
+```python
+from conans import ConanFile
+import os
+
+class SayConan(ConanFile):
+    name = "say"
+    version = "0.1"
+    exports_sources = "say_sources/*"
+    ...
+    def layout(self):
+        self.folders.source = "say_sources"
+        build_type = str(self.settings.build_type).lower()
+        self.folders.build = "cmake-build-{}".format(build_type)
+        self.folders.generators = os.path.join(self.folders.build, "conan")
+
+        self.cpp.package.libs = ["say"]
+        self.cpp.package.includedirs = ["include"] # includedirs is already set to this value by 
+                                                   # default, but declared for completion
+
+        # self.cpp.source and self.cpp.build are used for editable mode
+        # this information is relative to the source and build folders
+        self.cpp.source.includedirs = ["hpp"] # maps to ./say_sources/hpp
+        self.cpp.build.libdirs = ["."]        # maps to ./cmake-build-<build_type>
+        self.cpp.build.bindirs = ["."]        # maps to ./cmake-build-<build_type>
+
+    def build(self):
+        ...
+```
+
+We can set several attributes in the [layout()](https://docs.conan.io/en/latest/reference/conanfile/methods.html#layout) method, for example, those related to where the sources are and where we want to build the package:
+  - As we have our sources in the *say_sources* folder, `self.folders.source` is set to
+  `"./say_sources"`. 
+  - We are using CMake for building, so we want to set the build folder to
+  `cmake-build-release` or `cmake-build-debug` depending on the `build_type`. 
+  - The `self.folders.generators` folder is where all files generated by Conan will be stored so they don't
+  pollute the other folders.
+
+Please, note that the values above are for a single-configuration CMake generator. To support
+multi-configuration generators, such as Visual Studio, you should make some changes to this layout. For
+a complete layout that supports both single-config and multi-config please check the
+[cmake_layout()](https://docs.conan.io/en/latest/reference/conanfile/tools/layout.html#predefined-layouts)
+in the Conan documentation.
+
+Also, we can set the information about the package that the consumers need to use by setting
+the conanfile's
+[cpp.package](https://docs.conan.io/en/latest/developing_packages/package_layout.html#self-cpp)
+attributes values:
+  - Declaring `self.cpp.package.libs` inside the `layout()` method is equivalent to the "classic"
+    `self.cpp_info.libs` declaration in the `package_info()` method. 
+  - Also, as you may know, `self.cpp.package.includedirs` is set to `["include"]` [by
+    default](https://docs.conan.io/en/latest/reference/conanfile/attributes.html?highlight=includedirs#cpp-info),
+    so there's no need in declaring it but we are leaving it here for completeness.
+
+Setting `self.cpp.package.includedirs` to `["include"]` means that, when the package is not in
+editable mode, consumers will try to find the `say.h` file in a folder in the cache that corresponds
+to something similar to this:
+
+```
+/location/of/cache/data/say/0.1/_/_/package/<package_id>/include
+```
+
+As you can see, we don't have that structure in our local folder so we need a way to tell the `say` package consumers where to find the include file there when it's in editable mode. We can set that information using the conanfile's `cpp.source` and
+`cpp.build` attributes (which are [cpp_info objects](https://docs.conan.io/en/latest/reference/conanfile/attributes.html#cpp-info)):
+
+  - `self.cpp.source`: to set folders where the source files are (like include files) **relative to the `self.folders.source`**.
+  In this example we are setting `self.cpp.source.includedirs = ["hpp"]`. The `self.folders.source` information will be automatically prepended to that path for consumers so Conan will try to get the include files from the `./say_sources/hpp` folder.
+  - `self.cpp.build`:  to set folders where the built files are (like libraries or binary files) **relative to the `self.folders.build`**. 
+  As before, you don't have to prepend the build folder (`cmake-build-release` or `cmake-build-debug`) and if we set the `self.cpp.build.libdirs` and `self.cpp.build.bindirs` to `["."]`, Conan will try to find libraries and binaries in the `./cmake-build-<build_type>` folder.
+
+Note that the information set in `self.cpp.source` and `self.cpp.build` will be merged with the information set
+in `self.cpp.package` so that  we don't have to declare again something like `self.cpp.build.libs = ["say"]` 
+that is the same for the consumers independently of if the package is in editable mode or not.
+
+With those declared, we could put the package in editable mode, build it and other packages that
+require `say` would consume it in a completely transparent way.
+
+Please, for a complete example on how to use editable packages and layout, check the [Conan
+Examples](https://github.com/conan-io/examples/tree/master/features/editable/cmake) repository.
+
+## Intel oneAPI support in Conan 1.41
+
+Starting in this version you cant set the compiler setting to the `intel-cc` value to use the Intel
+compilers from the Intel oneAPI toolkits. This setting has a mode sub-setting to define the actual
+compiler you want to use from the [Base or HPC
+Toolkits](https://software.intel.com/content/www/us/en/develop/tools/oneapi/all-toolkits.html#gs.d9m4rs).
+It can take the [following values](https://docs.conan.io/en/latest/howtos/intel_compiler.html#intel-cc):
+
+- `icx`: Intel oneAPI C++ Compiler (icx/icpx)
+- `dpcpp`: Intel oneAPI DPC++ Compiler (dpcpp)
+- `classic`: Intel C++ Compiler Classic (icc/icpc for Linux/macOS and icl for Windows)
+
+Also, [IntelCC](https://docs.conan.io/en/latest/reference/conanfile/tools/intel.html#intelcc) has
+been added as a generator for Conan. Please check more about this feature in the [Conan
+documentation](https://docs.conan.io/en/latest/reference/conanfile/tools/intel.html).
+
+## Multi-config support for environment generators
+
+Since [Conan 1.35](https://docs.conan.io/en/latest/reference/conanfile/tools/env.html), [new
+tools](https://docs.conan.io/en/latest/reference/conanfile/tools/env.html) are available for managing
+environments. Now, the generated files for
+[VirtualRunEnv](https://docs.conan.io/en/latest/reference/conanfile/tools/env/virtualbuildenv.html)
+and
+[VirtualBuildEnv](https://docs.conan.io/en/latest/reference/conanfile/tools/env/virtualrunenv.html)
+take the ``build_type`` and ``arch`` settings into account for the names of the launcher files to
+improve the integration with multi-configuration generators. So, for example, calling to ``conan
+install cmake/3.20.0@ -g VirtualBuildEnv --build-require -s build_type=Release`` for example will
+create a file called ``conanbuildenv-release-x86_64.sh`` and will not be overwritten for other
+``build_type`` values.
+
+Also, now it is possible to group the generated environment variables launcher scripts under
+different names. By default, they are all aggregated to the group ``build`` for
+[Environment](https://docs.conan.io/en/latest/reference/conanfile/tools/env/environment.html) and
+``VirtualeBuildEnv`` and group ``run`` for ``VirtualRunEnv`` leading to a
+``conan(build/run).(sh/bat)`` script that sets all the declared environments. Now declaring something
+like this in the conanfile:
+
+```python
+class PkgConan(ConanFile):
+    ...
+    def generate(self):
+        tc = CMakeToolchain(self)
+        tc.generate()
+        env1 = Environment(self)
+        env1.define("env_name", "env1")
+        env1.save_script("env1_launcher", group="mygroup")
+        env2 = Environment(self)
+        env2.define("env_name", "env2")
+        env2.save_script("env2_launcher", group="mygroup")
+        env3 = Environment(self)
+        env2.define("env_name", "env3")
+        env2.save_script("env3_launcher")
+    ...
+  ```
+
+Will create a `conanmygroup.sh` file to set both `env1` and `env2` and a default `conanbuild.sh` that will
+only set `env3` variables.
+
+
+## Define object files in cpp_info.objects new attribute
+
+Starting in Conan 1.41 you can set a list of object files (_.obj_ and _.o_) in the
+[cpp_info](https://docs.conan.io/en/latest/reference/conanfile/attributes.html#cpp-info) `objects`
+attribute. This attribute is only compatible with the
+[CMakeDeps](https://docs.conan.io/en/latest/reference/conanfile/tools/cmake/cmakedeps.html) generator
+for the moment. It will add the declared objects to the generated CMake target so those objects can
+be later consumed by packages that declare the dependency.
+
+Let's suppose we create a Linux package `pkg/1.0` that builds and packages one _myobject.obj_ file. The same way
+you would declare the libraries that must be consumed by packages that depend on `pkg/1.0` setting
+the `cpp_info.libs` attribute, you can declare that this library packages some object files that the
+consumers need to add. This can be done by setting that information in the [package_info()](https://docs.conan.io/en/latest/reference/conanfile/methods.html#method-package-info) method of the
+conanfile:
+
+```python
+class Pkg(ConanFile):
+    name = 'pkg'
+    version = '1.0'
+    ...
+    def package_info(self):
+        self.cpp_info.objects = ['lib/myobject.o']
+    ...
+```
+
+Then, when this package is consumed by other packages using the `CMakeDeps` generator, the path of that object
+will be added to the target so the consumers can link against that _myobject.obj_ file.
+
+
+## Use different toolchains in the same recipe
+
+New toolchains create a file named __conanbuild.conf__ to pass certain information to the build
+helpers. The filename was the same for all the toolchains causing a collision problem when a recipe
+used different build systems. Conan 1.41 provides a new argument _namespace_ to the tools helpers for
+[CMake](https://docs.conan.io/en/latest/reference/conanfile/tools/cmake/cmake.html),
+[Bazel](https://docs.conan.io/en/latest/reference/conanfile/tools/google.html), and
+[Autotools](https://docs.conan.io/en/latest/reference/conanfile/tools/gnu.html). This argument makes
+it possible to use more than one toolchain in the same recipe, for example, when parts of the same
+package build with different build systems. Set this value to append the namespace to the filename
+(like __conanbuild_namespace.conf__), generating as unique name for each tool. A conanfile using this
+argument for the tools could look like this:
+
+```python
+  from conans import ConanFile
+  from conan.tools.gnu import AutotoolsToolchain, Autotools
+  from conan.tools.google import BazelToolchain, Bazel
+  from conan.tools.cmake import CMakeToolchain, CMake
+
+  class Conan(ConanFile):
+      settings = "os", "arch", "compiler", "build_type"
+      def generate(self):
+          # generates conanbuild_autotools.conf
+          autotools = AutotoolsToolchain(self, namespace='autotools')
+          autotools.generate() 
+
+          # generates conanbuild_bazel.conf
+          bazel = BazelToolchain(self, namespace='bazel')
+          bazel.generate()     
+
+          # generates conanbuild_cmake.conf
+          cmake = CMakeToolchain(self, namespace='cmake')
+          cmake.generate()     
+
+      def build(self):
+          # reads conanbuild_autotools.conf
+          autotools = Autotools(self, namespace='autotools')
+          autotools.configure() 
+          autotools.make()
+
+          # reads conanbuild_bazel.conf
+          bazel = Bazel(self, namespace='bazel')
+          bazel.configure()    
+          bazel.build(label="//main:hello-world")
+
+          # reads conanbuild_bazel.conf
+          cmake = CMake(self, namespace='cmake')
+          cmake.configure()   
+          cmake.build()
+  ```
+
+---
+
+<br>
+
+Besides the items listed above, there were some minor bug fixes you may wish to
+read about. If so, please refer to the
+[changelog](https://docs.conan.io/en/latest/changelog.html#oct-2021) for the
+complete list.
+
+We hope you enjoy this release, and look forward to [your
+feedback](https://github.com/conan-io/conan/issues).