Deprecate meson.build_root() and meson.source_root()

Those function are common source of issue when used in a subproject because they
point to the parent project root which is rarely what is expected and is a
violation of subproject isolation.

3 files changed, 13 insertions, 6 deletions

diff --git a/docs/markdown/Reference-manual.md b/docs/markdown/Reference-manual.md
index c289397..2f9e2de 100644
--- a/docs/markdown/Reference-manual.md
+++ b/docs/markdown/Reference-manual.md
@@ -1804,17 +1804,17 @@ the following methods.
   or `xcode`.
 
 - `build_root()`: returns a string with the absolute path to the build
-  root directory. Note: this function will return the build root of
-  the parent project if called from a subproject, which is usually
+  root directory. *(deprecated since 0.56.0)*: this function will return the
+  build root of the parent project if called from a subproject, which is usually
   not what you want. Try using `current_build_dir()`.
 
 - `source_root()`: returns a string with the absolute path to the
   source root directory. Note: you should use the `files()` function
   to refer to files in the root source directory instead of
-  constructing paths manually with `meson.source_root()`. This
-  function will return the source root of the parent project if called
-  from a subproject, which is usually not what you want. Try using
-  `current_source_dir()`.
+  constructing paths manually with `meson.source_root()`.
+  *(deprecated since 0.56.0)*: This function will return the source root of the
+  parent project if called from a subproject, which is usually not what you want.
+  Try using `current_source_dir()`.
 
 - `current_build_dir()`: returns a string with the absolute path to the
   current build directory.
diff --git a/docs/markdown/snippets/deprecate_source_build_root.md b/docs/markdown/snippets/deprecate_source_build_root.md
new file mode 100644
index 0000000..05b6b91
--- /dev/null
+++ b/docs/markdown/snippets/deprecate_source_build_root.md
@@ -0,0 +1,5 @@
+## `meson.build_root()` and `meson.source_root()` are deprecated
+
+Those function are common source of issue when used in a subproject because they
+point to the parent project root which is rarely what is expected and is a
+violation of subproject isolation.
diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index 3af5b51..7df5571 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -2061,11 +2061,13 @@ class MesonMain(InterpreterObject):
 
     @noPosargs
     @permittedKwargs({})
+    @FeatureDeprecated('meson.source_root', '0.56.0', 'use meson.current_source_dir instead.')
     def source_root_method(self, args, kwargs):
         return self.interpreter.environment.source_dir
 
     @noPosargs
     @permittedKwargs({})
+    @FeatureDeprecated('meson.build_root', '0.56.0', 'use meson.current_build_dir instead.')
     def build_root_method(self, args, kwargs):
         return self.interpreter.environment.build_dir