Allow setting the dtrace binary (#2607)

Allow setting the dtrace binary in `dtrace_compile`.

apple/dtrace.bzl

@@ -39,6 +39,10 @@ def _dtrace_compile_impl(ctx):
     output_hdrs = []
     include_dir = None
 
+    dtrace = "/usr/sbin/dtrace"
+    if ctx.executable.dtrace:
+        dtrace = ctx.executable.dtrace
+
     for src in ctx.files.srcs:
         owner_relative_path = bundle_paths.owner_relative_path(src)
         label_scoped_owner_path = ctx.label.name + "/" + owner_relative_path.lstrip("/")
@@ -53,7 +57,7 @@ def _dtrace_compile_impl(ctx):
             inputs = [src],
             outputs = [hdr],
             mnemonic = "dtraceCompile",
-            executable = "/usr/sbin/dtrace",
+            executable = dtrace,
             arguments = ["-h", "-s", src.path, "-o", hdr.path],
             progress_message = ("Compiling dtrace probes %s" % (src.basename)),
         )
@@ -77,6 +81,12 @@ def _dtrace_compile_impl(ctx):
 dtrace_compile = rule(
     implementation = _dtrace_compile_impl,
     attrs = dicts.add(apple_support.action_required_attrs(), {
+        "dtrace": attr.label(
+            doc = "dtrace binary to use.",
+            mandatory = False,
+            executable = True,
+            cfg = "exec",
+        ),
         "srcs": attr.label_list(
             allow_files = [".d"],
             allow_empty = False,

doc/rules-dtrace.md

@@ -7,7 +7,7 @@
 ## dtrace_compile
 
 <pre>
-dtrace_compile(<a href="#dtrace_compile-name">name</a>, <a href="#dtrace_compile-srcs">srcs</a>)
+dtrace_compile(<a href="#dtrace_compile-name">name</a>, <a href="#dtrace_compile-srcs">srcs</a>, <a href="#dtrace_compile-dtrace">dtrace</a>)
 </pre>
 
 Compiles
@@ -32,5 +32,6 @@ and a target named `dtrace_gen` the header path would be
 | :------------- | :------------- | :------------- | :------------- | :------------- |
 | <a id="dtrace_compile-name"></a>name |  A unique name for this target.   | <a href="https://bazel.build/concepts/labels#target-names">Name</a> | required |  |
 | <a id="dtrace_compile-srcs"></a>srcs |  dtrace(.d) source files to be compiled.   | <a href="https://bazel.build/concepts/labels">List of labels</a> | optional |  `[]`  |
+| <a id="dtrace_compile-dtrace"></a>dtrace |  dtrace binary to use.   | <a href="https://bazel.build/concepts/labels">Label</a> | optional |  `None`  |