New cmake layout default src folder (#2225)

* Update docs for the new default cmake_layout() source folder

* Update creating_packages/getting_started.rst

Co-authored-by: Carlos Zoido <mrgalleta@gmail.com>

* Fix wrong code block

Co-authored-by: Carlos Zoido <mrgalleta@gmail.com>

creating_packages/getting_started.rst

@@ -26,18 +26,19 @@ Using the :command:`conan new` command will create a "Hello World" C++ library e
     $ mkdir hellopkg && cd hellopkg
     $ conan new hello/0.1 --template=cmake_lib
     File saved: conanfile.py
-    File saved: src/CMakeLists.txt
+    File saved: CMakeLists.txt
     File saved: src/hello.cpp
     File saved: src/hello.h
     File saved: test_package/conanfile.py
-    File saved: test_package/src/CMakeLists.txt
+    File saved: test_package/CMakeLists.txt
     File saved: test_package/src/example.cpp
 
 
 The generated files are:
 
-- **conanfile.py**: On the root folder, there is a *conanfile.py* which is the main recipe file, responsible for defining how the package is built and consumed.
-- **src** folder: the *src* folder that contains the simple C++ "hello" library with a simple generic *CMakeLists.txt* to build it, with nothing specific about Conan in it.
+- **conanfile.py**: On the root folder, there is a *conanfile.py* which is the main recipe file, responsible for defining how the package is built and consumed. 
+- **CMakeLists.txt**: A simple generic *CMakeLists.txt*, with nothing specific about Conan in it.
+- **src** folder: the *src* folder that contains the simple C++ "hello" library.
 - (optional) **test_package** folder: contains an *example* application that will require and link with the created package.
   It is not mandatory, but it is useful to check that our package is correctly created.
 
@@ -59,7 +60,7 @@ Let's have a look at the package recipe *conanfile.py*:
         default_options = {"shared": False, "fPIC": True}
 
         # Sources are located in the same place as this recipe, copy them to the recipe
-        exports_sources = "src/*"
+        exports_sources = "CMakeLists.txt", "src/*"
 
         def config_options(self):
             if self.settings.os == "Windows":

reference/conanfile/tools/layout.rst

@@ -78,7 +78,7 @@ attributes described before:
         else:
             multi = False
 
-        conanfile.folders.source = "src"
+        conanfile.folders.source = "."
         if multi:
             conanfile.folders.build = "build"
             conanfile.folders.generators = "build/conan"
@@ -87,11 +87,13 @@ attributes described before:
             conanfile.folders.build = "cmake-build-{}".format(build_type)
             conanfile.folders.generators = os.path.join(conanfile.folders.build, "conan")
 
-        conanfile.cpp.source.includedirs = ["."]
+        conanfile.cpp.source.includedirs = ["src"]
         if multi:
             conanfile.cpp.build.libdirs = ["{}".format(conanfile.settings.build_type)]
+            conanfile.cpp.build.bindirs = ["{}".format(conanfile.settings.build_type)]
         else:
             conanfile.cpp.build.libdirs = ["."]
+            conanfile.cpp.build.bindirs = ["."]
 
 First, it is important to notice that the layout depends on the CMake generator that will be used.
 So if defined from ``[conf]``, that value will be used. If defined in recipe, then the recipe should
@@ -107,8 +109,9 @@ Finally, the location where the libraries are created also depends. For multi-co
 will be located in a dedicated folder inside the build folder, while for single-config, the libraries will
 be located directly in the build folder.
 
-This helper defines a few things, for example that the source folder is called ``"src"``. This could be customized
-without fully changing the layout:
+This helper defines a few things, for example that the source folder is called ``"."``, meaning that Conan will
+search the main `CMakeLists.txt` in the same directory were the conanfile is (most likely the project root).
+This could be customized without fully changing the layout:
 
     def layout(self):
         cmake_layout(self)
@@ -117,4 +120,4 @@ without fully changing the layout:
 
 Even if this pre-defined layout doesn't suit your specific projects layout, it is a good example how you could
 implement your own logic (and probably put it in a common ``python_require`` if you are going to use it in multiple
-packages).
+packages).