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Add non-const char* overload to LookupByKey #8848

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Add non-const char* overload to LookupByKey #8848

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37f04d3
add non const overload
jtdavis777 Dec 14, 2025
518b977
update generated code
jtdavis777 Dec 14, 2025
9d59a8c
update additional genned file
jtdavis777 Dec 14, 2025
e47a16d
Merge branch 'master' into fix/lookup_by_key_with_char
jtdavis777 Dec 14, 2025
806a792
Merge branch 'master' into fix/lookup_by_key_with_char
jtdavis777 Dec 20, 2025
b77711c
add test
jtdavis777 Dec 22, 2025
d9f09a0
Merge branch 'master' into fix/lookup_by_key_with_char
jtdavis777 Dec 24, 2025
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21 changes: 21 additions & 0 deletions include/flatbuffers/reflection_generated.h
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Original file line number Diff line number Diff line change
Expand Up @@ -275,6 +275,9 @@ struct KeyValue FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_key) const {
return strcmp(key()->c_str(), _key);
}
int KeyCompareWithValue(char *_key) const {
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@dbaileychess dbaileychess Dec 21, 2025

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Why can we not just make this the only version? I believe const char * passed into a char * will work.

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@jtdavis777 jtdavis777 Dec 21, 2025

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Thats a great suggestion. Will implement.

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@aardappel aardappel Dec 21, 2025

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const char * passed to char * generally won't work?

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@dbaileychess dbaileychess Dec 21, 2025

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Sorry, I meant to write it the other way around.

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@jtdavis777 jtdavis777 Dec 21, 2025

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I knew what you meant :) it just depends on if the argument match considers it close enough.

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@jtdavis777 jtdavis777 Dec 22, 2025

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oh, no, this is the root of the issue. the original version is a const char* only -- the issue is that a const char* maps onto the templated version template<typename StringType> int KeyCompareWithValue(const StringType&)

So the two options are either

  1. providing an explicit overload for char*, or
  2. adding SFINAE conditions to the template deduction (which is a bit gross in C++11)

return KeyCompareWithValue(static_cast<const char *>(_key));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _key) const {
if (key()->c_str() < _key) return -1;
Expand Down Expand Up @@ -473,6 +476,9 @@ struct Enum FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down Expand Up @@ -632,6 +638,9 @@ struct Field FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down Expand Up @@ -857,6 +866,9 @@ struct Object FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down Expand Up @@ -1016,6 +1028,9 @@ struct RPCCall FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down Expand Up @@ -1139,6 +1154,9 @@ struct Service FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down Expand Up @@ -1265,6 +1283,9 @@ struct SchemaFile FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_filename) const {
return strcmp(filename()->c_str(), _filename);
}
int KeyCompareWithValue(char *_filename) const {
return KeyCompareWithValue(static_cast<const char *>(_filename));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _filename) const {
if (filename()->c_str() < _filename) return -1;
Expand Down
6 changes: 6 additions & 0 deletions src/idl_gen_cpp.cpp
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Expand Up @@ -2608,6 +2608,12 @@ class CppGenerator : public BaseGenerator {
code_ += " int KeyCompareWithValue(const char *_{{FIELD_NAME}}) const {";
code_ += " return strcmp({{FIELD_NAME}}()->c_str(), _{{FIELD_NAME}});";
code_ += " }";
// Crate an explicit overload for char*.
code_ += " int KeyCompareWithValue(char *_{{FIELD_NAME}}) const {";
code_ +=
" return KeyCompareWithValue(static_cast<const char "
"*>(_{{FIELD_NAME}}));";
code_ += " }";
// Compares key against any string-like object (e.g. std::string_view or
// std::string) that implements operator< comparison with const char*.
code_ += " template<typename StringType>";
Expand Down
3 changes: 3 additions & 0 deletions tests/cpp17/generated_cpp17/monster_test_generated.h
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Expand Up @@ -1447,6 +1447,9 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down
3 changes: 3 additions & 0 deletions tests/key_field/key_field_sample_generated.h
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Expand Up @@ -598,6 +598,9 @@ struct FooTable FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_c) const {
return strcmp(c()->c_str(), _c);
}
int KeyCompareWithValue(char *_c) const {
return KeyCompareWithValue(static_cast<const char *>(_c));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _c) const {
if (c()->c_str() < _c) return -1;
Expand Down
22 changes: 22 additions & 0 deletions tests/key_field_test.cpp
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Expand Up @@ -12,6 +12,28 @@ namespace tests {

using namespace keyfield::sample;

void CallLookupByKeyOnString() {
flatbuffers::FlatBufferBuilder fbb;
const auto foo = keyfield::sample::CreateFooTable(
fbb, 1, 2, fbb.CreateString("TEST_STRING"));
fbb.Finish(foo);
uint8_t* buf = fbb.GetBufferPointer();
auto foo_table = GetFooTable(buf);

TEST_EQ(foo_table->KeyCompareWithValue("TEST_STRING"), 0);
TEST_NE(foo_table->KeyCompareWithValue("AAA"), 0);

// now compare with std::string
TEST_EQ(foo_table->KeyCompareWithValue(std::string{"TEST_STRING"}), 0);
TEST_NE(foo_table->KeyCompareWithValue(std::string{"AAA"}), 0);

// now compare with a mutable char*
char mutable_str[] = "TEST_STRING";
TEST_EQ(foo_table->KeyCompareWithValue(mutable_str), 0);
char mutable_str2[] = "AAA";
TEST_NE(foo_table->KeyCompareWithValue(mutable_str2), 0);
}

void FixedSizedScalarKeyInStructTest() {
flatbuffers::FlatBufferBuilder fbb;
std::vector<Baz> bazs;
Expand Down
1 change: 1 addition & 0 deletions tests/key_field_test.h
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Expand Up @@ -4,6 +4,7 @@
namespace flatbuffers {
namespace tests {

void CallLookupByKeyOnString();
void FixedSizedScalarKeyInStructTest();
void StructKeyInStructTest();
void NestedStructKeyInStructTest();
Expand Down
3 changes: 3 additions & 0 deletions tests/monster_test_generated.h
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Expand Up @@ -1463,6 +1463,9 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down
3 changes: 3 additions & 0 deletions tests/monster_test_suffix/ext_only/monster_test_generated.hpp
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Expand Up @@ -1454,6 +1454,9 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down
3 changes: 3 additions & 0 deletions tests/monster_test_suffix/filesuffix_only/monster_test_suffix.h
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Expand Up @@ -1454,6 +1454,9 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down
3 changes: 3 additions & 0 deletions tests/monster_test_suffix/monster_test_suffix.hpp
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Expand Up @@ -1454,6 +1454,9 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
int KeyCompareWithValue(const char *_name) const {
return strcmp(name()->c_str(), _name);
}
int KeyCompareWithValue(char *_name) const {
return KeyCompareWithValue(static_cast<const char *>(_name));
}
template<typename StringType>
int KeyCompareWithValue(const StringType& _name) const {
if (name()->c_str() < _name) return -1;
Expand Down
1 change: 1 addition & 0 deletions tests/test.cpp
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Expand Up @@ -1829,6 +1829,7 @@ int FlatBufferTests(const std::string& tests_data_path) {
JsonUnsortedArrayTest();
VectorSpanTest();
NativeInlineTableVectorTest();
CallLookupByKeyOnString();
FixedSizedScalarKeyInStructTest();
StructKeyInStructTest();
NestedStructKeyInStructTest();
Expand Down
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