patch_inplace assumes StringType is std::string

[tomalakgeretkal]

Description

patch_inplace has several instances of get<std::string>, which breaks the build if you're using a custom string.

Reproduction steps

• Instantiate a nlohmann::basic_json<> with a custom string type
• Attempt to call nlohmann:basic_json<>::patch

Expected vs. actual results

Compilation fails.

Minimal code example

struct MyString;  // some compatible impl

using Value = nlohmann::basic_json<
		std::map,
		std::vector,
		MyString,
		bool,
		std::int64_t,
		std::uint64_t,
		double,
		
		std::allocator,
		nlohmann::adl_serializer,
		std::vector<std::uint8_t>
>;

Value base, patch;
base.patch(patch);

Error messages

No matching constructor for initialization of 'nlohmann::basic_json<std::map, std::vector, MyString >::json_pointer' (aka 'json_pointer< MyString >')

Compiler and operating system

Apple clang version 14.0.3 (clang-1403.0.22.14.1), macOS Ventura 13.5.1

Library version

3.11.2

Validation

• The bug also occurs if the latest version from the develop branch is used.
• I can successfully compile and run the unit tests.

[falbrechtskirchinger]

Seems easy enough to fix. If you care to submit a PR, please add a regression test to tests/src/unit-alt-string.cpp.

[nlohmann]

@tomalakgeretkal Please take a look at #4536.