Allow export of function values

[turbolent]

Closes #2049

Description

Event though function cannot be serialized, we should still treat them as exportable: values are simply omitted.

This allows the export of composite values that contain function-typed fields. For example, this the NFT metadata standard contains such a definition.

Also, improve the tests by changing the static return type to AnyStruct and asserting the dynamic type checked for exportability.

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• [x] Targeted PR against master branch
• [x] Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• [x] Code follows the standards mentioned here
• [x] Updated relevant documentation
• [x] Re-reviewed Files changed in the Github PR explorer
• [x] Added appropriate labels

[github-actions[bot]]

Cadence Benchstat comparison

This branch with compared with the base branch onflow:master commit 77938db03296e2e34fb28fbaf2f94bbbe7b8ef3d The command for i in {1..N}; do go test ./... -run=XXX -bench=. -benchmem -shuffle=on; done was used. Bench tests were run a total of 7 times on each branch.

Collapsed results for better readability

	old.txt	new.txt
	time/op		delta
CheckContractInterfaceFungibleTokenConformance-2	119µs ± 2%	120µs ± 1%	~	(p=0.383 n=7+7)
ContractInterfaceFungibleToken-2	40.9µs ± 1%	41.1µs ± 1%	~	(p=0.535 n=7+7)
InterpretRecursionFib-2	2.40ms ± 1%	2.36ms ± 1%	−1.66%	(p=0.001 n=7+6)
NewInterpreter/new_interpreter-2	1.13µs ± 1%	1.13µs ± 0%	+0.67%	(p=0.017 n=7+6)
NewInterpreter/new_sub-interpreter-2	598ns ± 1%	611ns ± 5%	~	(p=0.318 n=7+7)
ParseArray-2	8.39ms ± 5%	8.34ms ± 2%	~	(p=0.731 n=7+6)
ParseDeploy/byte_array-2	12.6ms ± 4%	12.5ms ± 1%	~	(p=0.534 n=7+6)
ParseDeploy/decode_hex-2	1.23ms ± 1%	1.23ms ± 0%	~	(p=0.699 n=6+6)
ParseFungibleToken/With_memory_metering-2	190µs ± 2%	193µs ± 4%	~	(p=0.073 n=7+7)
ParseFungibleToken/Without_memory_metering-2	151µs ± 2%	153µs ± 2%	+1.87%	(p=0.002 n=6+7)
ParseInfix-2	7.24µs ± 1%	7.25µs ± 1%	~	(p=1.000 n=7+7)
QualifiedIdentifierCreation/One_level-2	2.35ns ± 0%	2.35ns ± 0%	~	(p=0.717 n=7+6)
QualifiedIdentifierCreation/Three_levels-2	136ns ± 1%	138ns ± 0%	+1.65%	(p=0.001 n=6+7)
RuntimeFungibleTokenTransfer-2	649µs ±25%	600µs ±29%	~	(p=0.902 n=7+7)
RuntimeResourceDictionaryValues-2	5.27ms ± 3%	5.29ms ± 3%	~	(p=0.805 n=7+7)
RuntimeScriptNoop-2	20.2µs ±28%	14.9µs ± 1%	~	(p=0.731 n=7+6)
ValueIsSubtypeOfSemaType-2	94.0ns ± 1%	95.6ns ± 6%	~	(p=0.383 n=7+7)
	alloc/op		delta
CheckContractInterfaceFungibleTokenConformance-2	50.1kB ± 0%	50.1kB ± 0%	~	(p=1.000 n=7+7)
ContractInterfaceFungibleToken-2	24.2kB ± 0%	24.2kB ± 0%	~	(all equal)
InterpretRecursionFib-2	1.00MB ± 0%	1.00MB ± 0%	~	(p=0.385 n=7+6)
NewInterpreter/new_interpreter-2	752B ± 0%	752B ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	200B ± 0%	200B ± 0%	~	(all equal)
ParseArray-2	2.71MB ± 2%	2.75MB ± 5%	~	(p=0.618 n=7+7)
ParseDeploy/byte_array-2	4.24MB ± 3%	4.21MB ± 3%	~	(p=0.512 n=7+7)
ParseDeploy/decode_hex-2	214kB ± 0%	214kB ± 0%	~	(p=0.152 n=7+7)
ParseFungibleToken/With_memory_metering-2	29.4kB ± 0%	29.4kB ± 0%	~	(p=0.816 n=7+7)
ParseFungibleToken/Without_memory_metering-2	29.4kB ± 0%	29.4kB ± 0%	~	(p=0.400 n=7+7)
ParseInfix-2	1.93kB ± 0%	1.93kB ± 0%	~	(p=0.554 n=7+7)
QualifiedIdentifierCreation/One_level-2	0.00B	0.00B	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	64.0B ± 0%	64.0B ± 0%	~	(all equal)
RuntimeFungibleTokenTransfer-2	103kB ± 1%	102kB ± 1%	~	(p=0.383 n=7+7)
RuntimeResourceDictionaryValues-2	2.28MB ± 0%	2.28MB ± 0%	−0.22%	(p=0.007 n=7+7)
RuntimeScriptNoop-2	8.67kB ± 1%	8.66kB ± 1%	~	(p=1.000 n=7+7)
ValueIsSubtypeOfSemaType-2	48.0B ± 0%	48.0B ± 0%	~	(all equal)
	allocs/op		delta
CheckContractInterfaceFungibleTokenConformance-2	900 ± 0%	900 ± 0%	~	(all equal)
ContractInterfaceFungibleToken-2	434 ± 0%	434 ± 0%	~	(all equal)
InterpretRecursionFib-2	18.9k ± 0%	18.9k ± 0%	~	(all equal)
NewInterpreter/new_interpreter-2	13.0 ± 0%	13.0 ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	4.00 ± 0%	4.00 ± 0%	~	(all equal)
ParseArray-2	69.6k ± 0%	69.6k ± 0%	~	(p=0.538 n=6+7)
ParseDeploy/byte_array-2	104k ± 0%	104k ± 0%	~	(p=1.000 n=7+7)
ParseDeploy/decode_hex-2	75.0 ± 0%	75.0 ± 0%	~	(all equal)
ParseFungibleToken/With_memory_metering-2	0.99k ± 0%	0.99k ± 0%	~	(all equal)
ParseFungibleToken/Without_memory_metering-2	0.99k ± 0%	0.99k ± 0%	~	(all equal)
ParseInfix-2	60.0 ± 0%	60.0 ± 0%	~	(all equal)
QualifiedIdentifierCreation/One_level-2	0.00	0.00	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	2.00 ± 0%	2.00 ± 0%	~	(all equal)
RuntimeFungibleTokenTransfer-2	2.05k ± 0%	2.05k ± 0%	~	(all equal)
RuntimeResourceDictionaryValues-2	37.0k ± 0%	37.0k ± 0%	~	(p=1.000 n=7+7)
RuntimeScriptNoop-2	141 ± 0%	141 ± 0%	~	(all equal)
ValueIsSubtypeOfSemaType-2	1.00 ± 0%	1.00 ± 0%	~	(all equal)

[codecov[bot]]

Codecov Report

Merging #2052 (baaa95f) into master (77938db) will increase coverage by 0.03%. The diff coverage is 72.09%.

@@            Coverage Diff             @@
##           master    #2052      +/-   ##
==========================================
+ Coverage   77.71%   77.74%   +0.03%     
==========================================
  Files         304      305       +1     
  Lines       63543    63572      +29     
==========================================
+ Hits        49381    49426      +45     
+ Misses      12405    12388      -17     
- Partials     1757     1758       +1     

Flag	Coverage Δ
unittests	77.74% <72.09%> (+0.03%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
runtime/common/memorykind_string.go	40.00% <ø> (ø)
runtime/common/metering.go	92.23% <ø> (ø)
types.go	90.22% <ø> (ø)
values.go	66.10% <43.75%> (-0.42%)	:arrow_down:
runtime/interpreter/function.go	71.95% <50.00%> (+4.07%)	:arrow_up:
encoding/json/encode.go	94.52% <83.33%> (+0.03%)	:arrow_up:
runtime/convertValues.go	80.05% <100.00%> (-0.06%)	:arrow_down:
runtime/format/function.go	100.00% <100.00%> (ø)
runtime/sema/type.go	89.58% <100.00%> (+0.08%)	:arrow_up:
runtime/script_executor.go	85.61% <0.00%> (-6.17%)	:arrow_down:
... and 5 more

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[dsainati1]

Just omitting the value seems suspect to me; it gives no information about what was originally present on that field. Can we instead emit some kind of dummy value that indicates that there was a function there originally?

[turbolent]

@dsainati1 What do you have in mind? Just an empty "function value"? I guess we could add the static type?

[dsainati1]

That or some text saying "Function Value Omitted", for example

[turbolent]

@dsainati1 Added a cadence.Function value which includes the function's type in acaef39

[dsainati1]

Nice. We should also update the json spec as well.

[turbolent]

@dsainati1 Added documentation in ae1c38c16cb9e8aafe684f032c14b3b3a7367d28