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Niels Lohmann
533cbfee51
Since #5877, the checked-in nlohmann_json.natvis only covers namespaces with up to two ABI tags. The generator gets options to produce a file for other configurations: - --abi-tags TAGS adds the namespaces of one configuration (repeatable) - --all generates every combination of ABI tags - --list-tags prints the tags with the macros that enable them - --output FILE writes somewhere else than the repository root `make natvis NATVIS_ARGS="..."` passes the options through. The default output is unchanged. The options are documented in the generator's README, the debugging page, and FILES.md, and checked in CI. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
66 lines
4.1 KiB
Markdown
66 lines
4.1 KiB
Markdown
# generate_natvis.py
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Generate the Natvis debugger visualization file for namespace combinations with up to two ABI tags.
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The checked-in `nlohmann_json.natvis` covers the default namespace (no ABI tags), every single ABI tag, and every pair
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of ABI tags, with both versioned and unversioned namespace variants. Configurations that enable three or more ABI tags
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are not covered by this reduced file; use `--abi-tags` or `--all` (see below) to generate a file for them.
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The ABI tag list and the library version are parsed from
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`include/nlohmann/detail/abi_macros.hpp`, so this script must be re-run (via
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`make natvis`) whenever an `NLOHMANN_JSON_ABI_TAG_*` macro is added to that
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file or the library version is bumped — otherwise the committed
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`nlohmann_json.natvis` drifts from the header it visualizes, and
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`make check-amalgamation` fails.
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## Usage
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```shell
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make natvis
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```
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`make natvis` sets up a virtual environment `tools/generate_natvis/venv` with the dependencies from
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`requirements.txt` (Jinja2) and runs the script with it. Alternatively, install the requirements yourself and run:
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```shell
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./generate_natvis.py [--version X.Y.Z] [--abi-tags TAGS]... [--all] [--list-tags] [--output FILE] [repository_root/]
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```
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`--version` and the repository root both default to values
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derived from this script's own location, so they only need to be given
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explicitly when generating a Natvis file for a different checkout or a
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version other than the one in `abi_macros.hpp`.
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| Option | Description |
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|-------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| `--list-tags` | Print every ABI tag (in namespace order) with the macro that enables it and the `NLOHMANN_JSON_ABI_TAG_*` identifier, then exit. |
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| `--abi-tags TAGS` | Add the namespaces of one configuration, given as a comma-separated list of ABI tags (`_diag,_dp,_vns`; the leading underscore is optional, and the order does not matter). Can be repeated for several configurations. Unknown tags are an error. |
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| `--all` | Generate the namespaces for every combination of ABI tags. The file size doubles with each tag (about 60 MB for 12 tags). Cannot be combined with `--abi-tags`. |
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| `--output FILE` | Write the Natvis file to `FILE` instead of `nlohmann_json.natvis` in the repository root. |
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Each configuration gets both the versioned (`json_abi_diag_dp_vns_v3_12_0`) and the unversioned (`json_abi_diag_dp_vns`,
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used with `NLOHMANN_JSON_NAMESPACE_NO_VERSION`) namespace. The default namespaces (up to two ABI tags) are always
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included, so a generated file can replace the checked-in one.
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### Generating a Natvis file for your configuration
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1. Check out the release tag of the library version you use (the ABI tags and the version are read from the checkout).
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2. Find the ABI tags of the macros you enable:
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```shell
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make natvis NATVIS_ARGS="--list-tags"
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```
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3. Generate a Natvis file with them, for example for `JSON_DIAGNOSTICS`, `JSON_DIAGNOSTIC_POSITIONS`, and
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`JSON_VIEW_NO_SIMD`:
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```shell
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make natvis NATVIS_ARGS="--abi-tags _diag,_dp,_vns --output my_nlohmann_json.natvis"
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```
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4. Use `my_nlohmann_json.natvis` instead of the shipped `nlohmann_json.natvis`, for example by adding it to your Visual
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Studio project.
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Passing `--output` keeps the checked-in `nlohmann_json.natvis` unchanged; without it, `make check-amalgamation` would
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report the file as out of date.
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