Automatically detect compiler features when running under Bazel. Before this commit, bazel builds used a hardcoded configuration, but that doesn't work e.g. on Windows where MSVC needs a different config.

21 files changed, 212 insertions, 73 deletions

diff --git a/BUILD b/BUILD
index 7d781ee..4c2aef5 100644
--- a/BUILD
+++ b/BUILD
@@ -6,8 +6,9 @@ filegroup(
     name = "fruit_headers",
     srcs = glob([
         "include/**/*.h",         
-        "configuration/bazel/**/*.h",
-    ]),
+    ]) + [
+        "//third_party/fruit/configuration/bazel:fruit_config",
+    ],
 )    
 
 cc_library(
@@ -15,7 +16,7 @@ cc_library(
     srcs = glob([
         "src/*.cpp",
         "include/fruit/impl/**/*.h",
-        "configuration/bazel/**/*.h"]),
+        ]) + ["//third_party/fruit/configuration/bazel:fruit_config"],
     hdrs = glob(["include/fruit/*.h"]),
     includes = ["include", "configuration/bazel"],
     deps = [
diff --git a/configuration/bazel/BUILD b/configuration/bazel/BUILD
new file mode 100644
index 0000000..112b732
--- /dev/null
+++ b/configuration/bazel/BUILD
@@ -0,0 +1,8 @@
+load("//third_party/fruit/configuration/bazel:build_defs.bzl", "generate_fruit_config")
+
+package(default_visibility = ["//third_party/fruit:__subpackages__"])
+
+generate_fruit_config(
+  name = "fruit_config",
+  check_sources = glob(["*.cpp"])
+)
diff --git a/configuration/bazel/always_inline_attribute.cpp b/configuration/bazel/always_inline_attribute.cpp
new file mode 100644
index 0000000..e6215af
--- /dev/null
+++ b/configuration/bazel/always_inline_attribute.cpp
@@ -0,0 +1,7 @@
+__attribute__((always_inline))
+void f() {
+}
+
+int main() {
+  return 0;
+}
diff --git a/configuration/bazel/attribute_deprecated.cpp b/configuration/bazel/attribute_deprecated.cpp
new file mode 100644
index 0000000..245519d
--- /dev/null
+++ b/configuration/bazel/attribute_deprecated.cpp
@@ -0,0 +1,5 @@
+[[deprecated]] void f();
+
+int main() {
+  return 0;
+}
diff --git a/configuration/bazel/build_defs.bzl b/configuration/bazel/build_defs.bzl
new file mode 100644
index 0000000..8d683c4
--- /dev/null
+++ b/configuration/bazel/build_defs.bzl
@@ -0,0 +1,85 @@
+load("@rules_cc//cc:action_names.bzl", "C_COMPILE_ACTION_NAME")
+load("@rules_cc//cc:toolchain_utils.bzl", "find_cpp_toolchain")
+
+def _generate_fruit_config_impl(ctx):
+    cc_toolchain = find_cpp_toolchain(ctx)
+
+    feature_configuration = cc_common.configure_features(
+        ctx = ctx,
+        cc_toolchain = cc_toolchain,
+        requested_features = ctx.features,
+        unsupported_features = ctx.disabled_features,
+    )
+    c_compiler_path = cc_common.get_tool_for_action(
+        feature_configuration = feature_configuration,
+        action_name = C_COMPILE_ACTION_NAME,
+    )
+
+    check_output_files = []
+    for check_source in ctx.files.check_sources:
+        output_file = ctx.actions.declare_file(check_source.path + ".o")
+
+        c_compile_variables = cc_common.create_compile_variables(
+            feature_configuration = feature_configuration,
+            cc_toolchain = cc_toolchain,
+            user_compile_flags = ctx.fragments.cpp.copts + ctx.fragments.cpp.conlyopts,
+            source_file = check_source.path,
+            output_file = output_file.path,
+        )
+        command_line = cc_common.get_memory_inefficient_command_line(
+            feature_configuration = feature_configuration,
+            action_name = C_COMPILE_ACTION_NAME,
+            variables = c_compile_variables,
+        )
+        env = cc_common.get_environment_variables(
+            feature_configuration = feature_configuration,
+            action_name = C_COMPILE_ACTION_NAME,
+            variables = c_compile_variables,
+        )
+
+        check_name = check_source.path.split('/')[-1].split('\\')[-1]
+        check_define = 'FRUIT_HAS_%s' % check_name.upper()
+        check_output_file = ctx.actions.declare_file(check_source.path + ".h")
+
+        ctx.actions.run_shell(
+            command = '"$@" &>/dev/null && echo "#define %s 1" >"%s" || echo "#define %s 0" >"%s"; touch "%s"' % (
+                check_define, check_output_file.path, check_define, check_output_file.path, output_file.path
+            ),
+            arguments = [c_compiler_path] + command_line,
+            env = env,
+            inputs = depset(
+                [check_source],
+                transitive = [cc_toolchain.all_files],
+            ),
+            outputs = [output_file, check_output_file],
+        )
+        check_output_files.append(check_output_file)
+
+    merged_output_file = ctx.actions.declare_file(ctx.label.name + ".h")
+    ctx.actions.run_shell(
+        command = '\n'.join([
+            '(',
+            'echo "#ifndef FRUIT_CONFIG_BASE_H"',
+            'echo "#define FRUIT_CONFIG_BASE_H"',
+            'echo "#define FRUIT_USES_BOOST 1"',
+            'cat %s' % ' '.join([check_output_file.path for check_output_file in check_output_files]),
+            'echo "#endif"',
+            ')>%s' % merged_output_file.path
+        ]),
+        inputs = check_output_files,
+        outputs = [merged_output_file],
+    )
+
+    return [
+        DefaultInfo(files = depset([merged_output_file])),
+    ]
+
+generate_fruit_config = rule(
+    implementation = _generate_fruit_config_impl,
+    attrs = {
+        "check_sources": attr.label_list(allow_files = True),
+        "_cc_toolchain": attr.label(default = Label("@bazel_tools//tools/cpp:current_cc_toolchain")),
+    },
+    toolchains = ["@bazel_tools//tools/cpp:toolchain_type"],
+    fragments = ["cpp"],
+)
\ No newline at end of file
diff --git a/configuration/bazel/builtin_unreachable.cpp b/configuration/bazel/builtin_unreachable.cpp
new file mode 100644
index 0000000..11d20cf
--- /dev/null
+++ b/configuration/bazel/builtin_unreachable.cpp
@@ -0,0 +1,13 @@
+int f() {
+  static int x = 1;
+  if (x == 1) {
+    return 0;
+  } else {
+    __builtin_unreachable();
+    // Note: the lack of return here is intentional
+  }
+}
+
+int main() {
+  return f();
+}
diff --git a/configuration/bazel/clang_arbitrary_overload_resolution_bug.cpp b/configuration/bazel/clang_arbitrary_overload_resolution_bug.cpp
new file mode 100644
index 0000000..67b4317
--- /dev/null
+++ b/configuration/bazel/clang_arbitrary_overload_resolution_bug.cpp
@@ -0,0 +1,11 @@
+template <typename T, typename U>
+struct Pair {};
+
+struct Map : public Pair<int, float>, Pair<int, char> {};
+
+template <typename Value>
+Value f(Pair<int, Value>*) { return Value(); }
+
+int main() {
+  f((Map*)0);
+}
diff --git a/configuration/bazel/constexpr_typeid.cpp b/configuration/bazel/constexpr_typeid.cpp
new file mode 100644
index 0000000..a793377
--- /dev/null
+++ b/configuration/bazel/constexpr_typeid.cpp
@@ -0,0 +1,6 @@
+#include <typeinfo>
+int main() {
+  constexpr static const std::type_info& x = typeid(int);
+  (void) x;
+  return 0;
+}
diff --git a/configuration/bazel/cxa_demangle.cpp b/configuration/bazel/cxa_demangle.cpp
new file mode 100644
index 0000000..3e4f57f
--- /dev/null
+++ b/configuration/bazel/cxa_demangle.cpp
@@ -0,0 +1,6 @@
+#include <cxxabi.h>
+int main() {
+  auto* p = abi::__cxa_demangle;
+  (void) p;
+  return 0;
+}
diff --git a/configuration/bazel/declspec_deprecated.cpp b/configuration/bazel/declspec_deprecated.cpp
new file mode 100644
index 0000000..79a9f43
--- /dev/null
+++ b/configuration/bazel/declspec_deprecated.cpp
@@ -0,0 +1,5 @@
+__declspec(deprecated) void f();
+
+int main() {
+  return 0;
+}
diff --git a/configuration/bazel/force_inline.cpp b/configuration/bazel/force_inline.cpp
new file mode 100644
index 0000000..fab42d2
--- /dev/null
+++ b/configuration/bazel/force_inline.cpp
@@ -0,0 +1,7 @@
+__forceinline
+void f() {
+}
+
+int main() {
+  return 0;
+}
diff --git a/configuration/bazel/fruit/impl/fruit-config-base.h b/configuration/bazel/fruit/impl/fruit-config-base.h
deleted file mode 100644
index 8e7af1d..0000000
--- a/configuration/bazel/fruit/impl/fruit-config-base.h
+++ /dev/null
@@ -1,70 +0,0 @@
-/*
- * Copyright 2014 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.
- */
-
-#ifndef FRUIT_CONFIG_BASE_H
-#define FRUIT_CONFIG_BASE_H
-
-// Needed for all Clang versions (as of January 2016), not needed for GCC.
-// This can also be defined for GCC, but it slightly slows down compile time of code using Fruit.
-#define FRUIT_HAS_CLANG_ARBITRARY_OVERLOAD_RESOLUTION_BUG 1
-
-// Whether the compiler defines std::max_align_t.
-#define FRUIT_HAS_STD_MAX_ALIGN_T 1
-
-// Whether the compiler defines ::max_align_t.
-// Ignored if FRUIT_HAS_STD_MAX_ALIGN_T is set.
-#define FRUIT_HAS_MAX_ALIGN_T 1
-
-// Whether the compiler defines std::is_trivially_copyable.
-#define FRUIT_HAS_STD_IS_TRIVIALLY_COPYABLE 1
-
-// Whether the compiler defines __has_trivial_copy.
-// Ignored if FRUIT_HAS_STD_IS_TRIVIALLY_COPYABLE is set.
-#define FRUIT_HAS_HAS_TRIVIAL_COPY 1
-
-// Whether the compiler defines __is_trivially_copyable.
-// Ignored if FRUIT_HAS_STD_IS_TRIVIALLY_COPYABLE is set.
-#define FRUIT_HAS_IS_TRIVIALLY_COPYABLE 1
-
-// Whether the compiler defines std::is_trivially_copy_constructible.
-#define FRUIT_HAS_STD_IS_TRIVIALLY_COPY_CONSTRUCTIBLE 1
-
-// Whether typeid() is available. Typically, it is unless RTTI is disabled.
-#define FRUIT_HAS_TYPEID 1
-
-// Whether typeid() is constexpr. Typically, it is except in MSVC.
-#define FRUIT_HAS_CONSTEXPR_TYPEID 1
-
-// Whether abi::__cxa_demangle() is available after including cxxabi.h.
-#define FRUIT_HAS_CXA_DEMANGLE 1
-
-#define FRUIT_USES_BOOST 1
-
-#define FRUIT_HAS_ALWAYS_INLINE_ATTRIBUTE 1
-
-#define FRUIT_HAS_FORCEINLINE 0
-
-#define FRUIT_HAS_ATTRIBUTE_DEPRECATED 0
-
-#define FRUIT_HAS_GCC_ATTRIBUTE_DEPRECATED 1
-
-#define FRUIT_HAS_DECLSPEC_DEPRECATED 0
-
-#define FRUIT_HAS_MSVC_ASSUME 0
-
-#define FRUIT_HAS_BUILTIN_UNREACHABLE 1
-
-#endif // FRUIT_CONFIG_BASE_H
diff --git a/configuration/bazel/gcc_attribute_deprecated.cpp b/configuration/bazel/gcc_attribute_deprecated.cpp
new file mode 100644
index 0000000..6d0bf5f
--- /dev/null
+++ b/configuration/bazel/gcc_attribute_deprecated.cpp
@@ -0,0 +1,5 @@
+void f() __attribute__((deprecated));
+
+int main() {
+  return 0;
+}
diff --git a/configuration/bazel/has_trivial_copy.cpp b/configuration/bazel/has_trivial_copy.cpp
new file mode 100644
index 0000000..b9da7d1
--- /dev/null
+++ b/configuration/bazel/has_trivial_copy.cpp
@@ -0,0 +1,5 @@
+int main() {
+  bool b = __has_trivial_copy(int);
+  (void) b;
+  return 0;
+}
diff --git a/configuration/bazel/is_trivially_copyable.cpp b/configuration/bazel/is_trivially_copyable.cpp
new file mode 100644
index 0000000..b8b7379
--- /dev/null
+++ b/configuration/bazel/is_trivially_copyable.cpp
@@ -0,0 +1,5 @@
+int main() {
+  bool b = __is_trivially_copyable(int);
+  (void) b;
+  return 0;
+}
diff --git a/configuration/bazel/max_align_t.cpp b/configuration/bazel/max_align_t.cpp
new file mode 100644
index 0000000..37342f1
--- /dev/null
+++ b/configuration/bazel/max_align_t.cpp
@@ -0,0 +1,5 @@
+#include <cstddef>
+using X = max_align_t;
+int main() {
+  return 0;
+}
diff --git a/configuration/bazel/msvc_assume.cpp b/configuration/bazel/msvc_assume.cpp
new file mode 100644
index 0000000..cd9f6ed
--- /dev/null
+++ b/configuration/bazel/msvc_assume.cpp
@@ -0,0 +1,13 @@
+int f() {
+  static int x = 1;
+  if (x == 1) {
+    return 0;
+  } else {
+    __assume(0);
+    // Note: the lack of return here is intentional
+  }
+}
+
+int main() {
+  return f();
+}
diff --git a/configuration/bazel/std_is_trivially_copy_constructible.cpp b/configuration/bazel/std_is_trivially_copy_constructible.cpp
new file mode 100644
index 0000000..7cb8d5b
--- /dev/null
+++ b/configuration/bazel/std_is_trivially_copy_constructible.cpp
@@ -0,0 +1,6 @@
+#include <type_traits>
+int main() {
+  bool b = std::is_trivially_copy_constructible<int>::value;
+  (void) b;
+  return 0;
+}
diff --git a/configuration/bazel/std_is_trivially_copyable.cpp b/configuration/bazel/std_is_trivially_copyable.cpp
new file mode 100644
index 0000000..871b793
--- /dev/null
+++ b/configuration/bazel/std_is_trivially_copyable.cpp
@@ -0,0 +1,6 @@
+#include <type_traits>
+int main() {
+  bool b = std::is_trivially_copyable<int>::value;
+  (void) b;
+  return 0;
+}
diff --git a/configuration/bazel/std_max_align_t.cpp b/configuration/bazel/std_max_align_t.cpp
new file mode 100644
index 0000000..acec695
--- /dev/null
+++ b/configuration/bazel/std_max_align_t.cpp
@@ -0,0 +1,5 @@
+#include <cstddef>
+using X = std::max_align_t;
+int main() {
+  return 0;
+}
diff --git a/configuration/bazel/typeid.cpp b/configuration/bazel/typeid.cpp
new file mode 100644
index 0000000..9621d03
--- /dev/null
+++ b/configuration/bazel/typeid.cpp
@@ -0,0 +1,5 @@
+#include <typeinfo>
+int main() {
+  (void) typeid(int);
+  return 0;
+}