tree eb569376a928d6080f17530d915063bb6dbe5ea6
parent 74dc4f3dba1c76efc24eb9dfbe21d9b38d42309f
author adonovan <adonovan@google.com> 1583962339 -0700
committer Copybara-Service <copybara-worker@google.com> 1583962423 -0700

bazel packages: add --record_rule_instantiation_callstack flag

This flag (default: false) causes each rule to record the Starlark
call stack at the moment of its instantiation.

The stacks are displayed by blaze query --output=build.

Example output:

        # /workspace/x/BUILD:2:1
        cc_library(
          name = "a",
          ...
        )
        # Instantiation stack:
        #   /workspace/x/inc.bzl:4:3 called from g
        #   /workspace/x/inc.bzl:2:3 called from f
        #   /workspace/x/BUILD:2:1   called from <toplevel>

By combining two optimizations, prefix sharing using a linked tree,
and element compression using packed integers, this feature
imposes an additional retained heap space cost of only 1.5%
for deps(//X) where X is Google's web server.

PiperOrigin-RevId: 300408104