bp2build: export some cc toolchain flags into Starlark.
This CL exports common/global/device/host clang/ld/ldd flags
from their Ninja variable initialization locations in
cc/config/global.go and cc/config/clang.go to make Bazel's cc_toolchain
and Soong's cc actions more consistent with each other.
This does not handle env-dependent or arch-specific toolchain flags
yet (logic in compiler.go and linker.go).
Test: TH
Bug: 187086342
Bug: 187084737
Bug: 186628704
Bug: 187857770
Change-Id: Ie403d7cd23f35160897b9dd902c799cbf1bd7f0c
diff --git a/cc/config/Android.bp b/cc/config/Android.bp
index 5ef247d..e4a8b62 100644
--- a/cc/config/Android.bp
+++ b/cc/config/Android.bp
@@ -10,6 +10,7 @@
"soong-remoteexec",
],
srcs: [
+ "bp2build.go",
"clang.go",
"global.go",
"tidy.go",
@@ -31,6 +32,7 @@
"arm64_linux_host.go",
],
testSrcs: [
+ "bp2build_test.go",
"tidy_test.go",
],
}
diff --git a/cc/config/bp2build.go b/cc/config/bp2build.go
new file mode 100644
index 0000000..16892e6
--- /dev/null
+++ b/cc/config/bp2build.go
@@ -0,0 +1,148 @@
+// Copyright 2021 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+ "android/soong/android"
+ "fmt"
+ "regexp"
+ "strings"
+)
+
+// Helpers for exporting cc configuration information to Bazel.
+
+var (
+ // Map containing toolchain variables that are independent of the
+ // environment variables of the build.
+ exportedVars = exportedVariablesMap{}
+)
+
+// variableValue is a string slice because the exported variables are all lists
+// of string, and it's simpler to manipulate string lists before joining them
+// into their final string representation.
+type variableValue []string
+
+// envDependentVariable is a toolchain variable computed based on an environment variable.
+type exportedVariablesMap map[string]variableValue
+
+func (m exportedVariablesMap) Set(k string, v variableValue) {
+ m[k] = v
+}
+
+// Convenience function to declare a static variable and export it to Bazel's cc_toolchain.
+func staticVariableExportedToBazel(name string, value []string) {
+ pctx.StaticVariable(name, strings.Join(value, " "))
+ exportedVars.Set(name, variableValue(value))
+}
+
+// BazelCcToolchainVars generates bzl file content containing variables for
+// Bazel's cc_toolchain configuration.
+func BazelCcToolchainVars() string {
+ ret := "# GENERATED FOR BAZEL FROM SOONG. DO NOT EDIT.\n\n"
+
+ // Ensure that string s has no invalid characters to be generated into the bzl file.
+ validateCharacters := func(s string) string {
+ for _, c := range []string{`\n`, `"`, `\`} {
+ if strings.Contains(s, c) {
+ panic(fmt.Errorf("%s contains illegal character %s", s, c))
+ }
+ }
+ return s
+ }
+
+ // For each exported variable, recursively expand elements in the variableValue
+ // list to ensure that interpolated variables are expanded according to their values
+ // in the exportedVars scope.
+ for _, k := range android.SortedStringKeys(exportedVars) {
+ variableValue := exportedVars[k]
+ var expandedVars []string
+ for _, v := range variableValue {
+ expandedVars = append(expandedVars, expandVar(v, exportedVars)...)
+ }
+ // Build the list for this variable.
+ list := "["
+ for _, flag := range expandedVars {
+ list += fmt.Sprintf("\n \"%s\",", validateCharacters(flag))
+ }
+ list += "\n]"
+ // Assign the list as a bzl-private variable; this variable will be exported
+ // out through a constants struct later.
+ ret += fmt.Sprintf("_%s = %s\n", k, list)
+ ret += "\n"
+ }
+
+ // Build the exported constants struct.
+ ret += "constants = struct(\n"
+ for _, k := range android.SortedStringKeys(exportedVars) {
+ ret += fmt.Sprintf(" %s = _%s,\n", k, k)
+ }
+ ret += ")"
+ return ret
+}
+
+// expandVar recursively expand interpolated variables in the exportedVars scope.
+//
+// We're using a string slice to track the seen variables to avoid
+// stackoverflow errors with infinite recursion. it's simpler to use a
+// string slice than to handle a pass-by-referenced map, which would make it
+// quite complex to track depth-first interpolations. It's also unlikely the
+// interpolation stacks are deep (n > 1).
+func expandVar(toExpand string, exportedVars map[string]variableValue) []string {
+ // e.g. "${ClangExternalCflags}"
+ r := regexp.MustCompile(`\${([a-zA-Z0-9_]+)}`)
+
+ // Internal recursive function.
+ var expandVarInternal func(string, map[string]bool) []string
+ expandVarInternal = func(toExpand string, seenVars map[string]bool) []string {
+ var ret []string
+ for _, v := range strings.Split(toExpand, " ") {
+ matches := r.FindStringSubmatch(v)
+ if len(matches) == 0 {
+ return []string{v}
+ }
+
+ if len(matches) != 2 {
+ panic(fmt.Errorf(
+ "Expected to only match 1 subexpression in %s, got %d",
+ v,
+ len(matches)-1))
+ }
+
+ // Index 1 of FindStringSubmatch contains the subexpression match
+ // (variable name) of the capture group.
+ variable := matches[1]
+ // toExpand contains a variable.
+ if _, ok := seenVars[variable]; ok {
+ panic(fmt.Errorf(
+ "Unbounded recursive interpolation of variable: %s", variable))
+ }
+ // A map is passed-by-reference. Create a new map for
+ // this scope to prevent variables seen in one depth-first expansion
+ // to be also treated as "seen" in other depth-first traversals.
+ newSeenVars := map[string]bool{}
+ for k := range seenVars {
+ newSeenVars[k] = true
+ }
+ newSeenVars[variable] = true
+ unexpandedVars := exportedVars[variable]
+ for _, unexpandedVar := range unexpandedVars {
+ ret = append(ret, expandVarInternal(unexpandedVar, newSeenVars)...)
+ }
+ }
+ return ret
+ }
+
+ return expandVarInternal(toExpand, map[string]bool{})
+}
diff --git a/cc/config/bp2build_test.go b/cc/config/bp2build_test.go
new file mode 100644
index 0000000..7744b4b
--- /dev/null
+++ b/cc/config/bp2build_test.go
@@ -0,0 +1,91 @@
+// Copyright 2021 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+ "testing"
+)
+
+func TestExpandVars(t *testing.T) {
+ testCases := []struct {
+ description string
+ exportedVars map[string]variableValue
+ toExpand string
+ expectedValues []string
+ }{
+ {
+ description: "single level expansion",
+ exportedVars: map[string]variableValue{
+ "foo": variableValue([]string{"bar"}),
+ },
+ toExpand: "${foo}",
+ expectedValues: []string{"bar"},
+ },
+ {
+ description: "double level expansion",
+ exportedVars: map[string]variableValue{
+ "foo": variableValue([]string{"${bar}"}),
+ "bar": variableValue([]string{"baz"}),
+ },
+ toExpand: "${foo}",
+ expectedValues: []string{"baz"},
+ },
+ {
+ description: "double level expansion with a literal",
+ exportedVars: map[string]variableValue{
+ "a": variableValue([]string{"${b}", "c"}),
+ "b": variableValue([]string{"d"}),
+ },
+ toExpand: "${a}",
+ expectedValues: []string{"d", "c"},
+ },
+ {
+ description: "double level expansion, with two variables in a string",
+ exportedVars: map[string]variableValue{
+ "a": variableValue([]string{"${b} ${c}"}),
+ "b": variableValue([]string{"d"}),
+ "c": variableValue([]string{"e"}),
+ },
+ toExpand: "${a}",
+ expectedValues: []string{"d", "e"},
+ },
+ {
+ description: "triple level expansion with two variables in a string",
+ exportedVars: map[string]variableValue{
+ "a": variableValue([]string{"${b} ${c}"}),
+ "b": variableValue([]string{"${c}", "${d}"}),
+ "c": variableValue([]string{"${d}"}),
+ "d": variableValue([]string{"foo"}),
+ },
+ toExpand: "${a}",
+ expectedValues: []string{"foo", "foo", "foo"},
+ },
+ }
+
+ for _, testCase := range testCases {
+ t.Run(testCase.description, func(t *testing.T) {
+ output := expandVar(testCase.toExpand, testCase.exportedVars)
+ if len(output) != len(testCase.expectedValues) {
+ t.Errorf("Expected %d values, got %d", len(testCase.expectedValues), len(output))
+ }
+ for i, actual := range output {
+ expectedValue := testCase.expectedValues[i]
+ if actual != expectedValue {
+ t.Errorf("Actual value '%s' doesn't match expected value '%s'", actual, expectedValue)
+ }
+ }
+ })
+ }
+}
diff --git a/cc/config/clang.go b/cc/config/clang.go
index 5e46d5a..4fbb9c3 100644
--- a/cc/config/clang.go
+++ b/cc/config/clang.go
@@ -98,7 +98,7 @@
}
func init() {
- pctx.StaticVariable("ClangExtraCflags", strings.Join([]string{
+ staticVariableExportedToBazel("ClangExtraCflags", []string{
"-D__compiler_offsetof=__builtin_offsetof",
// Emit address-significance table which allows linker to perform safe ICF. Clang does
@@ -151,9 +151,9 @@
// This macro allows the bionic versioning.h to indirectly determine whether the
// option -Wunguarded-availability is on or not.
"-D__ANDROID_UNAVAILABLE_SYMBOLS_ARE_WEAK__",
- }, " "))
+ })
- pctx.StaticVariable("ClangExtraCppflags", strings.Join([]string{
+ staticVariableExportedToBazel("ClangExtraCppflags", []string{
// -Wimplicit-fallthrough is not enabled by -Wall.
"-Wimplicit-fallthrough",
@@ -162,13 +162,11 @@
// libc++'s math.h has an #include_next outside of system_headers.
"-Wno-gnu-include-next",
- }, " "))
+ })
- pctx.StaticVariable("ClangExtraTargetCflags", strings.Join([]string{
- "-nostdlibinc",
- }, " "))
+ staticVariableExportedToBazel("ClangExtraTargetCflags", []string{"-nostdlibinc"})
- pctx.StaticVariable("ClangExtraNoOverrideCflags", strings.Join([]string{
+ staticVariableExportedToBazel("ClangExtraNoOverrideCflags", []string{
"-Werror=address-of-temporary",
// Bug: http://b/29823425 Disable -Wnull-dereference until the
// new cases detected by this warning in Clang r271374 are
@@ -203,11 +201,11 @@
"-Wno-non-c-typedef-for-linkage", // http://b/161304145
// New warnings to be fixed after clang-r407598
"-Wno-string-concatenation", // http://b/175068488
- }, " "))
+ })
// Extra cflags for external third-party projects to disable warnings that
// are infeasible to fix in all the external projects and their upstream repos.
- pctx.StaticVariable("ClangExtraExternalCflags", strings.Join([]string{
+ staticVariableExportedToBazel("ClangExtraExternalCflags", []string{
"-Wno-enum-compare",
"-Wno-enum-compare-switch",
@@ -228,7 +226,7 @@
// http://b/165945989
"-Wno-psabi",
- }, " "))
+ })
}
func ClangFilterUnknownCflags(cflags []string) []string {
diff --git a/cc/config/global.go b/cc/config/global.go
index 23106ec..59fe8e1 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -165,13 +165,25 @@
commonGlobalCflags = append(commonGlobalCflags, "-fdebug-prefix-map=/proc/self/cwd=")
}
- pctx.StaticVariable("CommonGlobalConlyflags", strings.Join(commonGlobalConlyflags, " "))
- pctx.StaticVariable("DeviceGlobalCppflags", strings.Join(deviceGlobalCppflags, " "))
- pctx.StaticVariable("DeviceGlobalLdflags", strings.Join(deviceGlobalLdflags, " "))
- pctx.StaticVariable("DeviceGlobalLldflags", strings.Join(deviceGlobalLldflags, " "))
- pctx.StaticVariable("HostGlobalCppflags", strings.Join(hostGlobalCppflags, " "))
- pctx.StaticVariable("HostGlobalLdflags", strings.Join(hostGlobalLdflags, " "))
- pctx.StaticVariable("HostGlobalLldflags", strings.Join(hostGlobalLldflags, " "))
+ staticVariableExportedToBazel("CommonGlobalConlyflags", commonGlobalConlyflags)
+ staticVariableExportedToBazel("DeviceGlobalCppflags", deviceGlobalCppflags)
+ staticVariableExportedToBazel("DeviceGlobalLdflags", deviceGlobalLdflags)
+ staticVariableExportedToBazel("DeviceGlobalLldflags", deviceGlobalLldflags)
+ staticVariableExportedToBazel("HostGlobalCppflags", hostGlobalCppflags)
+ staticVariableExportedToBazel("HostGlobalLdflags", hostGlobalLdflags)
+ staticVariableExportedToBazel("HostGlobalLldflags", hostGlobalLldflags)
+
+ // Export the static default CommonClangGlobalCflags to Bazel.
+ // TODO(187086342): handle cflags that are set in VariableFuncs.
+ commonClangGlobalCFlags := append(
+ ClangFilterUnknownCflags(commonGlobalCflags),
+ []string{
+ "${ClangExtraCflags}",
+ // Default to zero initialization.
+ "-ftrivial-auto-var-init=zero",
+ "-enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang",
+ }...)
+ exportedVars.Set("CommonClangGlobalCflags", variableValue(commonClangGlobalCFlags))
pctx.VariableFunc("CommonClangGlobalCflags", func(ctx android.PackageVarContext) string {
flags := ClangFilterUnknownCflags(commonGlobalCflags)
@@ -190,26 +202,26 @@
// Default to zero initialization.
flags = append(flags, "-ftrivial-auto-var-init=zero -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang")
}
-
return strings.Join(flags, " ")
})
+ // Export the static default DeviceClangGlobalCflags to Bazel.
+ // TODO(187086342): handle cflags that are set in VariableFuncs.
+ deviceClangGlobalCflags := append(ClangFilterUnknownCflags(deviceGlobalCflags), "${ClangExtraTargetCflags}")
+ exportedVars.Set("DeviceClangGlobalCflags", variableValue(deviceClangGlobalCflags))
+
pctx.VariableFunc("DeviceClangGlobalCflags", func(ctx android.PackageVarContext) string {
if ctx.Config().Fuchsia() {
return strings.Join(ClangFilterUnknownCflags(deviceGlobalCflags), " ")
} else {
- return strings.Join(append(ClangFilterUnknownCflags(deviceGlobalCflags), "${ClangExtraTargetCflags}"), " ")
+ return strings.Join(deviceClangGlobalCflags, " ")
}
})
- pctx.StaticVariable("HostClangGlobalCflags",
- strings.Join(ClangFilterUnknownCflags(hostGlobalCflags), " "))
- pctx.StaticVariable("NoOverrideClangGlobalCflags",
- strings.Join(append(ClangFilterUnknownCflags(noOverrideGlobalCflags), "${ClangExtraNoOverrideCflags}"), " "))
- pctx.StaticVariable("CommonClangGlobalCppflags",
- strings.Join(append(ClangFilterUnknownCflags(commonGlobalCppflags), "${ClangExtraCppflags}"), " "))
-
- pctx.StaticVariable("ClangExternalCflags", "${ClangExtraExternalCflags}")
+ staticVariableExportedToBazel("HostClangGlobalCflags", ClangFilterUnknownCflags(hostGlobalCflags))
+ staticVariableExportedToBazel("NoOverrideClangGlobalCflags", append(ClangFilterUnknownCflags(noOverrideGlobalCflags), "${ClangExtraNoOverrideCflags}"))
+ staticVariableExportedToBazel("CommonClangGlobalCppflags", append(ClangFilterUnknownCflags(commonGlobalCppflags), "${ClangExtraCppflags}"))
+ staticVariableExportedToBazel("ClangExternalCflags", []string{"${ClangExtraExternalCflags}"})
// Everything in these lists is a crime against abstraction and dependency tracking.
// Do not add anything to this list.