#190, #200 :: Migrate to new cc provider. (#209)

* #190, #200 :: Migrate to new cc provider.

* re-replace dep.cc.libs

Author: mfarrugi

bindgen/bindgen.bzl

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library")
+load("@io_bazel_rules_rust//rust:private/legacy_cc_starlark_api_shim.bzl", "get_libs_for_static_executable")
 
 def rust_bindgen_library(
         name,
@@ -44,7 +45,7 @@ def _rust_bindgen_impl(ctx):
     # nb. We can't grab the cc_library`s direct headers, so a header must be provided.
     cc_lib = ctx.attr.cc_lib
     header = ctx.file.header
-    if header not in cc_lib.cc.transitive_headers:
+    if header not in cc_lib[CcInfo].compilation_context.headers:
         fail("Header {} is not in {}'s transitive headers.".format(ctx.attr.header, cc_lib), "header")
 
     toolchain = ctx.toolchains["@io_bazel_rules_rust//bindgen:bindgen_toolchain"]
@@ -68,10 +69,10 @@ def _rust_bindgen_impl(ctx):
     output = ctx.outputs.out
 
     # libclang should only have 1 output file
-    libclang_dir = libclang.cc.libs.to_list()[0].dirname
-    include_directories = cc_lib.cc.include_directories
-    quote_include_directories = cc_lib.cc.quote_include_directories
-    system_include_directories = cc_lib.cc.system_include_directories
+    libclang_dir = get_libs_for_static_executable(libclang).to_list()[0].dirname
+    include_directories = cc_lib[CcInfo].compilation_context.includes.to_list()
+    quote_include_directories = cc_lib[CcInfo].compilation_context.quote_includes.to_list()
+    system_include_directories = cc_lib[CcInfo].compilation_context.system_includes.to_list()
 
     # Vanilla usage of bindgen produces formatted output, here we do the same if we have `rustfmt` in our toolchain.
     if rustfmt_bin:
@@ -92,7 +93,11 @@ def _rust_bindgen_impl(ctx):
         executable = bindgen_bin,
         inputs = depset(
             [header],
-            transitive = [cc_lib.cc.transitive_headers, libclang.cc.libs, libstdcxx.cc.libs],
+            transitive = [
+                cc_lib[CcInfo].compilation_context.headers,
+                get_libs_for_static_executable(libclang),
+                get_libs_for_static_executable(libstdcxx),
+            ],
         ),
         outputs = [unformatted_output],
         mnemonic = "RustBindgen",
@@ -102,7 +107,7 @@ def _rust_bindgen_impl(ctx):
             "CLANG_PATH": clang_bin.path,
             # Bindgen loads libclang at runtime, which also needs libstdc++, so we setup LD_LIBRARY_PATH
             "LIBCLANG_PATH": libclang_dir,
-            "LD_LIBRARY_PATH": ":".join([f.dirname for f in libstdcxx.cc.libs]),
+            "LD_LIBRARY_PATH": ":".join([f.dirname for f in get_libs_for_static_executable(libstdcxx)]),
         },
         arguments = [args],
         tools = [clang_bin],
@@ -126,7 +131,7 @@ rust_bindgen = rule(
         ),
         "cc_lib": attr.label(
             doc = "The cc_library that contains the .h file. This is used to find the transitive includes.",
-            providers = ["cc"],
+            providers = [CcInfo],
         ),
         "bindgen_flags": attr.string_list(
             doc = "Flags to pass directly to the bindgen executable. See https://rust-lang.github.io/rust-bindgen/ for details.",
@@ -173,12 +178,12 @@ rust_bindgen_toolchain = rule(
         "libclang": attr.label(
             doc = "A cc_library that provides bindgen's runtime dependency on libclang.",
             cfg = "host",
-            providers = ["cc"],
+            providers = [CcInfo],
         ),
         "libstdcxx": attr.label(
             doc = "A cc_library that satisfies libclang's libstdc++ dependency.",
             cfg = "host",
-            providers = ["cc"],
+            providers = [CcInfo],
         ),
     },
 )

rust/private/legacy_cc_starlark_api_shim.bzl

@@ -0,0 +1,24 @@
+"""
+Part of --incompatible_disable_legacy_cc_provider migration (https://github.com/bazelbuild/bazel/issues/7036)
+"""
+
+def get_libs_for_static_executable(dep):
+    """
+    This replaces dep.cc.libs, which found the libraries 
+    used for linking a static executable.
+    
+    Args:
+      dep: A cc_library target.
+    Returns:
+      A depset[File]
+    """
+    libraries_to_link = dep[CcInfo].linking_context.libraries_to_link
+    return depset([_get_preferred_artifact(lib) for lib in libraries_to_link])
+
+def _get_preferred_artifact(library_to_link):
+    return (
+        library_to_link.static_library or
+        library_to_link.pic_static_library or
+        library_to_link.interface_library or
+        library_to_link.dynamic_library
+    )

rust/private/rustc.bzl

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 load("@io_bazel_rules_rust//rust:private/utils.bzl", "relative_path")
+load("@io_bazel_rules_rust//rust:private/legacy_cc_starlark_api_shim.bzl", "get_libs_for_static_executable")
 load(
     "@bazel_tools//tools/build_defs/cc:action_names.bzl",
     "CPP_LINK_EXECUTABLE_ACTION_NAME",
@@ -106,10 +107,13 @@ def collect_deps(deps, toolchain):
             transitive_crates = depset(transitive = [transitive_crates, dep[DepInfo].transitive_crates])
             transitive_dylibs = depset(transitive = [transitive_dylibs, dep[DepInfo].transitive_dylibs])
             transitive_staticlibs = depset(transitive = [transitive_staticlibs, dep[DepInfo].transitive_staticlibs])
-        elif hasattr(dep, "cc"):
+        elif CcInfo in dep:
             # This dependency is a cc_library
-            dylibs = [l for l in dep.cc.libs.to_list() if l.basename.endswith(toolchain.dylib_ext)]
-            staticlibs = [l for l in dep.cc.libs.to_list() if l.basename.endswith(toolchain.staticlib_ext)]
+
+            # TODO: We could let the user choose how to link, instead of always preferring to link static libraries.
+            libs = get_libs_for_static_executable(dep)
+            dylibs = [l for l in libs.to_list() if l.basename.endswith(toolchain.dylib_ext)]
+            staticlibs = [l for l in libs.to_list() if l.basename.endswith(toolchain.staticlib_ext)]
             transitive_dylibs = depset(transitive = [transitive_dylibs, depset(dylibs)])
             transitive_staticlibs = depset(transitive = [transitive_staticlibs, depset(staticlibs)])
         else:
@@ -182,8 +186,7 @@ def rustc_compile_action(
         toolchain,
     )
 
-    linker_script = getattr(ctx.file, "linker_script") if hasattr(ctx.file, "linker_script") \
-            else None
+    linker_script = getattr(ctx.file, "linker_script") if hasattr(ctx.file, "linker_script") else None
 
     compile_inputs = depset(
         crate_info.srcs +