Fix cargo_bootstrap_repository not triggering on changes to srcs (#959)

* Consume srcs of `cargo_bootstrap_repository` so changes trigger the rule

* Regenerate documentation

* Improve logging

* Update cargo/cargo_bootstrap.bzl

Co-authored-by: Daniel Wagner-Hall <dawagner@gmail.com>

* Use formatted fail message over print

Co-authored-by: Daniel Wagner-Hall <dawagner@gmail.com>

Author: UebelAndre

cargo/cargo_bootstrap.bzl

@@ -8,6 +8,18 @@ _CARGO_BUILD_MODES = [
     "debug",
 ]
 
+_FAIL_MESSAGE = """\
+Process exited with code '{code}'
+# ARGV ########################################################################
+{argv}
+
+# STDOUT ######################################################################
+{stdout}
+
+# STDERR ######################################################################
+{stderr}
+"""
+
 def cargo_bootstrap(
         repository_ctx,
         cargo_bin,
@@ -69,8 +81,11 @@ def cargo_bootstrap(
     )
 
     if result.return_code != 0:
-        fail("exit_code: {}".format(
-            result.return_code,
+        fail(_FAIL_MESSAGE.format(
+            code = result.return_code,
+            argv = args,
+            stdout = result.stdout,
+            stderr = result.stderr,
         ))
 
     extension = ""
@@ -134,7 +149,25 @@ def _collect_environ(repository_ctx, host_triple):
 
     return dict(env_vars.items() + env_labels.items())
 
+def _detect_changes(repository_ctx):
+    """Inspect files that are considered inputs to the build for changes
+
+    Args:
+        repository_ctx (repository_ctx): The rule's context object.
+    """
+    # Simply generating a `path` object consideres the file as 'tracked' or
+    # 'consumed' which means changes to it will trigger rebuilds
+
+    for src in repository_ctx.attr.srcs:
+        repository_ctx.path(src)
+
+    repository_ctx.path(repository_ctx.attr.cargo_lockfile)
+    repository_ctx.path(repository_ctx.attr.cargo_toml)
+
 def _cargo_bootstrap_repository_impl(repository_ctx):
+    # Pretend to Bazel that this rule's input files have been used, so that it will re-run the rule if they change.
+    _detect_changes(repository_ctx)
+
     if repository_ctx.attr.version in ("beta", "nightly"):
         version_str = "{}-{}".format(repository_ctx.attr.version, repository_ctx.attr.iso_date)
     else:
@@ -223,9 +256,8 @@ cargo_bootstrap_repository = repository_rule(
             default = "rust_{system}_{arch}",
         ),
         "srcs": attr.label_list(
-            doc = "Souces to crate to build.",
+            doc = "Souce files of the crate to build. Passing source files here can be used to trigger rebuilds when changes are made",
             allow_files = True,
-            mandatory = True,
         ),
         "version": attr.string(
             doc = "The version of cargo the resolver should use",

crate_universe/bootstrap.bzl

@@ -11,7 +11,6 @@ def crate_universe_bootstrap():
         name = "rules_rust_crate_universe_bootstrap",
         cargo_lockfile = Label("//crate_universe:Cargo.lock"),
         cargo_toml = Label("//crate_universe:Cargo.toml"),
-        srcs = [Label("//crate_universe:resolver_srcs")],
         version = rust_common.default_version,
         binary = "crate_universe_resolver",
         env = {

docs/cargo.md

@@ -31,7 +31,7 @@ A rule for bootstrapping a Rust binary using [Cargo](https://doc.rust-lang.org/c
 | <a id="cargo_bootstrap_repository-iso_date"></a>iso_date |  The iso_date of cargo binary the resolver should use. Note: This can only be set if <code>version</code> is <code>beta</code> or <code>nightly</code>   | String | optional | "" |
 | <a id="cargo_bootstrap_repository-repo_mapping"></a>repo_mapping |  A dictionary from local repository name to global repository name. This allows controls over workspace dependency resolution for dependencies of this repository.&lt;p&gt;For example, an entry <code>"@foo": "@bar"</code> declares that, for any time this repository depends on <code>@foo</code> (such as a dependency on <code>@foo//some:target</code>, it should actually resolve that dependency within globally-declared <code>@bar</code> (<code>@bar//some:target</code>).   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | required |  |
 | <a id="cargo_bootstrap_repository-rust_toolchain_repository_template"></a>rust_toolchain_repository_template |  The template to use for finding the host <code>rust_toolchain</code> repository. <code>{version}</code> (eg. '1.53.0'), <code>{triple}</code> (eg. 'x86_64-unknown-linux-gnu'), <code>{system}</code> (eg. 'darwin'), and <code>{arch}</code> (eg. 'aarch64') will be replaced in the string if present.   | String | optional | "rust_{system}_{arch}" |
-| <a id="cargo_bootstrap_repository-srcs"></a>srcs |  Souces to crate to build.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | required |  |
+| <a id="cargo_bootstrap_repository-srcs"></a>srcs |  Souce files of the crate to build. Passing source files here can be used to trigger rebuilds when changes are made   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
 | <a id="cargo_bootstrap_repository-version"></a>version |  The version of cargo the resolver should use   | String | optional | "1.55.0" |
 
 

docs/flatten.md

@@ -92,7 +92,7 @@ A rule for bootstrapping a Rust binary using [Cargo](https://doc.rust-lang.org/c
 | <a id="cargo_bootstrap_repository-iso_date"></a>iso_date |  The iso_date of cargo binary the resolver should use. Note: This can only be set if <code>version</code> is <code>beta</code> or <code>nightly</code>   | String | optional | "" |
 | <a id="cargo_bootstrap_repository-repo_mapping"></a>repo_mapping |  A dictionary from local repository name to global repository name. This allows controls over workspace dependency resolution for dependencies of this repository.&lt;p&gt;For example, an entry <code>"@foo": "@bar"</code> declares that, for any time this repository depends on <code>@foo</code> (such as a dependency on <code>@foo//some:target</code>, it should actually resolve that dependency within globally-declared <code>@bar</code> (<code>@bar//some:target</code>).   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | required |  |
 | <a id="cargo_bootstrap_repository-rust_toolchain_repository_template"></a>rust_toolchain_repository_template |  The template to use for finding the host <code>rust_toolchain</code> repository. <code>{version}</code> (eg. '1.53.0'), <code>{triple}</code> (eg. 'x86_64-unknown-linux-gnu'), <code>{system}</code> (eg. 'darwin'), and <code>{arch}</code> (eg. 'aarch64') will be replaced in the string if present.   | String | optional | "rust_{system}_{arch}" |
-| <a id="cargo_bootstrap_repository-srcs"></a>srcs |  Souces to crate to build.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | required |  |
+| <a id="cargo_bootstrap_repository-srcs"></a>srcs |  Souce files of the crate to build. Passing source files here can be used to trigger rebuilds when changes are made   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
 | <a id="cargo_bootstrap_repository-version"></a>version |  The version of cargo the resolver should use   | String | optional | "1.55.0" |