Allow opting-out of the 0.0.0 crate version fallback

Author: dzbarsky

cargo/private/cargo_build_script.bzl

@@ -11,6 +11,7 @@ load("//rust:rust_common.bzl", "BuildInfo", "CrateGroupInfo", "DepInfo")
 # buildifier: disable=bzl-visibility
 load(
     "//rust/private:rustc.bzl",
+    "env_vars_from_version",
     "get_compilation_mode_opts",
     "get_linker_and_args",
 )
@@ -407,13 +408,7 @@ def _cargo_build_script_impl(ctx):
     })
 
     if ctx.attr.version:
-        version = ctx.attr.version.split("+")[0].split(".")
-        patch = version[2].split("-") if len(version) > 2 else [""]
-        env["CARGO_PKG_VERSION_MAJOR"] = version[0]
-        env["CARGO_PKG_VERSION_MINOR"] = version[1] if len(version) > 1 else ""
-        env["CARGO_PKG_VERSION_PATCH"] = patch[0]
-        env["CARGO_PKG_VERSION_PRE"] = patch[1] if len(patch) > 1 else ""
-        env["CARGO_PKG_VERSION"] = ctx.attr.version
+        env.update(env_vars_from_version(ctx.attr.version))
 
     # Pull in env vars which may be required for the cc_toolchain to work (e.g. on OSX, the SDK version).
     # We hope that the linker env is sufficient for the whole cc_toolchain.

rust/private/rustc.bzl

@@ -129,24 +129,40 @@ is_proc_macro_dep_enabled = rule(
     build_setting = config.bool(flag = True),
 )
 
-def _get_rustc_env(attr, toolchain, crate_name):
-    """Gathers rustc environment variables
+def env_vars_from_version(version):
+    """Gathers rustc environment variables corresponding to the version
 
     Args:
-        attr (struct): The current target's attributes
-        toolchain (rust_toolchain): The current target's rust toolchain context
-        crate_name (str): The name of the crate to be compiled
+        version (str): The version of the crate to be compiled
 
     Returns:
         dict: Rustc environment variables
     """
-    version = attr.version if hasattr(attr, "version") else "0.0.0"
     major, minor, patch = version.split(".", 2)
     if "-" in patch:
         patch, pre = patch.split("-", 1)
     else:
         pre = ""
 
+    return {
+        "CARGO_PKG_VERSION": version,
+        "CARGO_PKG_VERSION_MAJOR": major,
+        "CARGO_PKG_VERSION_MINOR": minor,
+        "CARGO_PKG_VERSION_PATCH": patch,
+        "CARGO_PKG_VERSION_PRE": pre,
+    }
+
+def _get_rustc_env(attr, toolchain, crate_name):
+    """Gathers rustc environment variables
+
+    Args:
+        attr (struct): The current target's attributes
+        toolchain (rust_toolchain): The current target's rust toolchain context
+        crate_name (str): The name of the crate to be compiled
+
+    Returns:
+        dict: Rustc environment variables
+    """
     result = {
         "CARGO_CFG_TARGET_ARCH": "" if toolchain.target_arch == None else toolchain.target_arch,
         "CARGO_CFG_TARGET_OS": "" if toolchain.target_os == None else toolchain.target_os,
@@ -155,12 +171,13 @@ def _get_rustc_env(attr, toolchain, crate_name):
         "CARGO_PKG_DESCRIPTION": "",
         "CARGO_PKG_HOMEPAGE": "",
         "CARGO_PKG_NAME": attr.name,
-        "CARGO_PKG_VERSION": version,
-        "CARGO_PKG_VERSION_MAJOR": major,
-        "CARGO_PKG_VERSION_MINOR": minor,
-        "CARGO_PKG_VERSION_PATCH": patch,
-        "CARGO_PKG_VERSION_PRE": pre,
     }
+
+    version_default = None if toolchain._incompatible_do_not_inject_degenerate_version_to_rustc_env else "0.0.0"
+    version = getattr(attr, "version", version_default)
+    if version:
+        result.update(env_vars_from_version(version))
+
     if hasattr(attr, "_is_proc_macro_dep_enabled") and attr._is_proc_macro_dep_enabled[IsProcMacroDepEnabledInfo].enabled:
         is_proc_macro_dep = "0"
         if hasattr(attr, "_is_proc_macro_dep") and attr._is_proc_macro_dep[IsProcMacroDepInfo].is_proc_macro_dep:

rust/settings/BUILD.bazel

@@ -27,6 +27,7 @@ load(
     "incompatible_change_clippy_error_format",
     "incompatible_change_rust_test_compilation_output_directory",
     "incompatible_do_not_include_data_in_compile_data",
+    "incompatible_do_not_inject_degenerate_version_to_rustc_env",
     "lto",
     "no_std",
     "pipelined_compilation",
@@ -111,6 +112,8 @@ incompatible_change_rust_test_compilation_output_directory()
 
 incompatible_do_not_include_data_in_compile_data()
 
+incompatible_do_not_inject_degenerate_version_to_rustc_env()
+
 lto()
 
 no_std()

rust/settings/settings.bzl

@@ -478,6 +478,15 @@ def incompatible_do_not_include_data_in_compile_data():
         issue = "https://github.com/bazelbuild/rules_rust/issues/2977",
     )
 
+def incompatible_do_not_inject_degenerate_version_to_rustc_env():
+    """A flag to control whether we inject env vars corresponding to version 0.0.0 if version is ommitted.
+    """
+    incompatible_flag(
+        name = "incompatible_do_not_inject_degenerate_version_to_rustc_env",
+        build_setting_default = False,
+        issue = "https://github.com/bazelbuild/rules_rust/issues/3674",
+    )
+
 def codegen_units():
     """The default value for `--codegen-units` which also affects resource allocation for rustc actions.
 

rust/toolchain.bzl

@@ -760,6 +760,7 @@ def _rust_toolchain_impl(ctx):
         _incompatible_change_rust_test_compilation_output_directory = ctx.attr._incompatible_change_rust_test_compilation_output_directory[IncompatibleFlagInfo].enabled,
         _toolchain_generated_sysroot = ctx.attr._toolchain_generated_sysroot[BuildSettingInfo].value,
         _incompatible_do_not_include_data_in_compile_data = ctx.attr._incompatible_do_not_include_data_in_compile_data[IncompatibleFlagInfo].enabled,
+        _incompatible_do_not_inject_degenerate_version_to_rustc_env = ctx.attr._incompatible_do_not_inject_degenerate_version_to_rustc_env[IncompatibleFlagInfo].enabled,
         _no_std = no_std,
         _codegen_units = ctx.attr._codegen_units[BuildSettingInfo].value,
         _experimental_use_allocator_libraries_with_mangled_symbols = ctx.attr.experimental_use_allocator_libraries_with_mangled_symbols,
@@ -986,6 +987,10 @@ rust_toolchain = rule(
             default = Label("//rust/settings:incompatible_do_not_include_data_in_compile_data"),
             doc = "Label to a boolean build setting that controls whether to include data files in compile_data.",
         ),
+        "_incompatible_do_not_inject_degenerate_version_to_rustc_env": attr.label(
+            default = Label("//rust/settings:incompatible_do_not_inject_degenerate_version_to_rustc_env"),
+            doc = "Label to a boolean build setting that controls whether to set rustc env vars based on a crate version of '0.0.0' if one is not explicitly provided. ",
+        ),
         "_no_std": attr.label(
             default = Label("//rust/settings:no_std"),
         ),