## Changes
Semantics for merging two instances of `config.Value`:
* Merging x with nil or nil with x always yields x
* Merging maps a and b means entries from map b take precedence
* Merging sequences a and b means concatenating them
These are the same semantics that we use today when calling into mergo
in `bundle/config`.
## Tests
Unit tests pass.
## Changes
This is similar to #904 but instead of converting the dynamic
configuration to Go structs, this normalizes a `config.Value` according
to the type of a Go struct and returns the new, normalized
`config.Value`.
This will be used to ensure that two `config.Value` trees are
type-compatible before we can merge them (i.e. instances from different
files).
Warnings and errors during normalization are accumulated and returned as
a `diag.Diagnostics` structure. We can use this to surface warnings
about unknown fields, or errors about invalid types, in aggregate
instead of one-by-one. This approach is inspired by the pattern to
accumulate diagnostics in Terraform provider code.
## Tests
New unit tests.
## Changes
Now that we have a new YAML loader (see #828), we need code to turn this
into our Go structs.
## Tests
New unit tests pass.
Confirmed that we can replace our existing loader/converter with this
one and that existing unit tests for bundle loading still pass.
## Changes
In order to support variable interpolation on fields that aren't a
string in the resource types, we need a separate representation of the
bundle configuration tree with the type equivalent of Go's `any`. But
instead of using `any` directly, we can do better and use a custom type
equivalent to `any` that captures additional metadata. In this PR, the
additional metadata is limited to the origin of the configuration value
(file, line number, and column).
The YAML in this commit uses the upstream YAML parser's `yaml.Node` type
to get access to location information. It reimplements the loader that
takes the `yaml.Node` structure and turns it into the configuration tree
we need.
Next steps after this PR:
* Implement configuration tree type checking (against a Go type)
* Implement configuration tree merging (to replace the current merge
functionality)
* Implement conversion to and from the bundle configuration struct
* Perform variable interpolation against this configuration tree (to
support variable interpolation for ints)
* (later) Implement a `jsonloader` that produces the same tree and
includes location information
## Tests
The tests in `yamlloader` perform an equality check on the untyped
output of loading a YAML file between the upstream YAML loader and this
loader. The YAML examples were generated by prompting ChatGPT for
examples that showcase anchors, primitive values, edge cases, etc.
Pieter Noordhuis