diff options
Diffstat (limited to 'absl/flags/flag.h')
| -rw-r--r-- | absl/flags/flag.h | 57 |
1 files changed, 34 insertions, 23 deletions
diff --git a/absl/flags/flag.h b/absl/flags/flag.h index 356ddb61..09af47a0 100644 --- a/absl/flags/flag.h +++ b/absl/flags/flag.h @@ -96,8 +96,7 @@ class Flag { constexpr Flag(const char* name, const flags_internal::HelpGenFunc help_gen, const char* filename, const flags_internal::FlagMarshallingOpFn marshalling_op, - const flags_internal::InitialValGenFunc initial_value_gen, - bool, void*) + const flags_internal::InitialValGenFunc initial_value_gen) : name_(name), help_gen_(help_gen), filename_(filename), @@ -115,8 +114,11 @@ class Flag { return impl_; } - impl_ = new flags_internal::Flag<T>(name_, help_gen_, filename_, - marshalling_op_, initial_value_gen_); + impl_ = new flags_internal::Flag<T>( + name_, + {flags_internal::FlagHelpSrc(help_gen_), + flags_internal::FlagHelpSrcKind::kGenFunc}, + filename_, marshalling_op_, initial_value_gen_); inited_.store(true, std::memory_order_release); } @@ -307,9 +309,19 @@ void SetFlag(absl::Flag<T>* flag, const V& v) { #define ABSL_FLAG_IMPL_FLAGHELP(txt) txt #endif -#define ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, txt) \ - static std::string AbslFlagsWrapHelp##name() { \ - return ABSL_FLAG_IMPL_FLAGHELP(txt); \ +// AbslFlagHelpGenFor##name is used to encapsulate both immediate (method Const) +// and lazy (method NonConst) evaluation of help message expression. We choose +// between the two via the call to HelpArg in absl::Flag instantiation below. +// If help message expression is constexpr evaluable compiler will optimize +// away this whole struct. +#define ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, txt) \ + struct AbslFlagHelpGenFor##name { \ + template <typename T = void> \ + static constexpr const char* Const() { \ + return absl::flags_internal::HelpConstexprWrap( \ + ABSL_FLAG_IMPL_FLAGHELP(txt)); \ + } \ + static std::string NonConst() { return ABSL_FLAG_IMPL_FLAGHELP(txt); } \ } #define ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ @@ -326,29 +338,28 @@ void SetFlag(absl::Flag<T>* flag, const V& v) { #define ABSL_FLAG_IMPL(Type, name, default_value, help) \ namespace absl /* block flags in namespaces */ {} \ ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ - ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help) \ + ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help); \ ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{ \ - ABSL_FLAG_IMPL_FLAGNAME(#name), &AbslFlagsWrapHelp##name, \ + ABSL_FLAG_IMPL_FLAGNAME(#name), \ + absl::flags_internal::HelpArg<AbslFlagHelpGenFor##name>(0), \ ABSL_FLAG_IMPL_FILENAME(), \ &absl::flags_internal::FlagMarshallingOps<Type>, \ &AbslFlagsInitFlag##name}; \ extern bool FLAGS_no##name; \ bool FLAGS_no##name = ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name) #else -// MSVC version uses aggregate initialization. -#define ABSL_FLAG_IMPL(Type, name, default_value, help) \ - namespace absl /* block flags in namespaces */ {} \ - ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ - ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help) \ - ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{ \ - ABSL_FLAG_IMPL_FLAGNAME(#name), \ - &AbslFlagsWrapHelp##name, \ - ABSL_FLAG_IMPL_FILENAME(), \ - &absl::flags_internal::FlagMarshallingOps<Type>, \ - &AbslFlagsInitFlag##name, \ - false, \ - nullptr}; \ - extern bool FLAGS_no##name; \ +// MSVC version uses aggregate initialization. We also do not try to +// optimize away help wrapper. +#define ABSL_FLAG_IMPL(Type, name, default_value, help) \ + namespace absl /* block flags in namespaces */ {} \ + ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ + ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help); \ + ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{ \ + ABSL_FLAG_IMPL_FLAGNAME(#name), &AbslFlagHelpGenFor##name::NonConst, \ + ABSL_FLAG_IMPL_FILENAME(), \ + &absl::flags_internal::FlagMarshallingOps<Type>, \ + &AbslFlagsInitFlag##name}; \ + extern bool FLAGS_no##name; \ bool FLAGS_no##name = ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name) #endif |