[browser] Support AppContext switches on runtime

[maraf]

AppContext switches defined in csproj are not available on runtime

<ItemGroup>
    ...
    <RuntimeHostConfigurationOption Include="System.Runtime.OptionalFeatureBehavior"
                                    Condition="'$(UnoptimizedUserFacingBehavior)' != ''"
                                    Value="$(UnoptimizedUserFacingBehavior)"
                                    Link="false" />
    ...
</ItemGroup>

On other platforms, they end up in runtime.config.json. We should put them into blazor.boot.json as that's the only config required (for both wasmbrowser and blazor experience)

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Issue Details

---

AppContext switches defined in csproj are not available on runtime

<ItemGroup>
    ...
    <RuntimeHostConfigurationOption Include="System.Runtime.OptionalFeatureBehavior"
                                    Condition="'$(UnoptimizedUserFacingBehavior)' != ''"
                                    Value="$(UnoptimizedUserFacingBehavior)"
                                    Link="false" />
    ...
</ItemGroup>

On other platforms, they end up in runtime.config.json. We should put them into blazor.boot.json as that's the only config required (for both wasmbrowser and blazor experience)

Author:	maraf
Assignees:	-
Labels:	arch-wasm, area-Build-mono, os-browser
Milestone:	9.0.0

[lewing]

AppContext switches defined in csproj are not available on runtime

<ItemGroup>
    ...
    <RuntimeHostConfigurationOption Include="System.Runtime.OptionalFeatureBehavior"
                                    Condition="'$(UnoptimizedUserFacingBehavior)' != ''"
                                    Value="$(UnoptimizedUserFacingBehavior)"
                                    Link="false" />
    ...
</ItemGroup>

On other platforms, they end up in runtime.config.json. We should put them into blazor.boot.json as that's the only config required (for both wasmbrowser and blazor experience)

That works for browser but we will have the same issue in wasi where there is no json parser.

[maraf]

That works for browser but we will have the same issue in wasi where there is no json parser.

That's true. We can use the binary format for WASI and we bundle it into wasm file even for browser, but I would like to avoid distributing it as a separate file for browser scenario

[lambdageek]

Mono has a task that converts rutnimeconfig.json files into a binary blob at build time so you don't need to do JSON parsing at execution time
https://github.com/dotnet/runtime/blob/main/src/tasks/MonoTargetsTasks/RuntimeConfigParser/RuntimeConfigParser.cs

the binary blob can be passed by the driver to monovm_runtimeconfig_initialize:

runtime/src/native/public/mono/jit/details/mono-private-unstable-functions.h

Line 21 in 77fd98c

MONO_API_FUNCTION(int, monovm_runtimeconfig_initialize, (MonovmRuntimeConfigArguments *arg, MonovmRuntimeConfigArgumentsCleanup cleanup_fn, void *user_data))

runtime/src/native/public/mono/jit/details/mono-private-unstable-types.h

Lines 21 to 34 in 77fd98c

	typedef struct {
	uint32_t kind; // 0 = Path of runtimeconfig.blob, 1 = pointer to image data, >= 2 undefined
	union {
	struct {
	const char *path;
	} name;
	struct {
	const char *data;
	uint32_t data_len;
	} data;
	} runtimeconfig;
	} MonovmRuntimeConfigArguments;
	typedef void (*MonovmRuntimeConfigArgumentsCleanup) (MonovmRuntimeConfigArguments *args, void *user_data);

This is used by xamarin-android, for example:

https://github.com/xamarin/xamarin-android/blob/e67afc7d7ae848da6b33026b80973d30713b98ad/src/monodroid/jni/monodroid-glue.cc#L846-L848