summaryrefslogtreecommitdiff
path: root/absl/flags/flag.h
diff options
context:
space:
mode:
Diffstat (limited to 'absl/flags/flag.h')
-rw-r--r--absl/flags/flag.h57
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