bazel build --incompatible_no_implicit_file_export

The Bazel build was relying, for the two files enumerated in this diff, on the legacy implicit-export semantics described here:
https://bazel.build/reference/be/functions#exports_files

This documentation page encourages migrating away from this legacy behavior, and indeed we have a user who reported a Bazel build error and it appears that they were already using the new, stricter behavior:
https://github.com/openxla/iree/pull/13982
and while examining fixes on our side and trying to get a clean Bazel build, I ran into this similar issue in the LLVM overlay.

It would arguably be cleaner (in the sense of more structured) to rely on `filegroup` to export this, but I am insufficiently familiar with the Clang build (the dependent targets seem to be below Clang) to do this myself. The present `exports_files` solution has the merit of being localized in these few lines here.

Differential Revision: https://reviews.llvm.org/D152491

diff --git a/utils/bazel/.bazelrc b/utils/bazel/.bazelrc
index b0f137f..c06e9b3 100644 (file)
--- a/utils/bazel/.bazelrc
+++ b/utils/bazel/.bazelrc
@@ -25,6 +25,11 @@ build --strip=never
 # Add layering check to all projects.
 build --features=layering_check
 
+# Opt out of legacy lax behavior implicitly exporting files that are rule inputs
+# with default visibility.
+# See: https://bazel.build/reference/be/functions#exports_files
+build --incompatible_no_implicit_file_export
+
 ###############################################################################
 # Options to select different strategies for linking potential dependent
 # libraries. The default leaves it disabled.

diff --git a/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel b/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel
index 0cc28fd..c43ab72 100644 (file)
--- a/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel
@@ -17,7 +17,18 @@ package(
 
 licenses(["notice"])
 
-exports_files(["LICENSE.TXT"])
+exports_files([
+    "LICENSE.TXT",
+    "cmake/modules/llvm-driver-template.cpp.in",
+    "include/llvm/CodeGen/SDNodeProperties.td",
+    "include/llvm/CodeGen/ValueTypes.td",
+    "include/llvm/Frontend/Directive/DirectiveBase.td",
+    "include/llvm/Frontend/OpenACC/ACC.td",
+    "include/llvm/Frontend/OpenMP/OMP.td",
+    "include/llvm/IR/Intrinsics.td",
+    "include/llvm/Option/OptParser.td",
+    "utils/lit/lit.py",
+])
 
 # It may be tempting to add compiler flags here, but that should be avoided.
 # The necessary warnings and other compile flags should be provided by the