Add this.exists() as an experimental feature

[tsmallig33]

Description

Adds this.exists() for use in resource properties. Should be blocked from usage in all other places as it is a runtime function.

Example Usage

resource storageAccount 'Microsoft.Storage/storageAccounts@2021-09-01' = {
  name: 'mystorageaccount'
  location: 'eastus'
  sku: {
    name: 'Standard_LRS'
  }
  kind: 'StorageV2'
  properties: {
    minimumTlsVersion: 'TLS1_2'
    publicNetworkAccess: this.exists() ? 'Enabled' : 'Disabled'
  }
}

Checklist

• I have read and adhere to the contribution guide.

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 18512672134)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 18512672134

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 18512672134"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 18512672134

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 18512672134"

[github-actions]

Dotnet Test Results

    96 files   -     48      96 suites   - 48   41m 21s ⏱️ - 35m 28s
12 434 tests +     4  12 434 ✅ +     4  0 💤 ±0  0 ❌ ±0 
28 613 runs   - 14 249  28 613 ✅  - 14 249  0 💤 ±0  0 ❌ ±0 

Results for commit f1f4fe6. ± Comparison against base commit f37ea76.

This pull request removes 1917 and adds 669 tests. Note that renamed tests count towards both.

		nestedProp1: 1
		nestedProp2: 2
		prop1: true
		prop2: false
	1
	2
	\$'")
	prop1: true
	prop2: false
…

Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000
�ӽ
�0\u0010\u0007��>E�\u0003�;{I���Ep�\u0001�=�b��\u0015
�\u001b\u0007q��h+��x9����K���e\Պ\u0010h�ħ�g�^�@�\u0000\u0002��\u0015!ۏO�¹n\�G�c�\u001f4I�k�S�\u0006(!0Z�Am�8�k��5�ʓkvi^fܪ}},��EW���\u000c:<��{W�.�\u0010�@
6�ZDŽ��\u001c\u001d�����?��EF���\u0013o\u001a�\u0016\���fr�\u000e5_��-\u0008� ��\u001b�϶|\u0000\u000c\u0000\u0000,"Value cannot be null. (Parameter 'source')")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000
�ӽ\u000e�0\u0010\u0007��>\u0005OP��\u001dŁ��Wh�ďP\u000c�@b|w�`�\u0000qA0����K���e�7��0Ǣn$!P,���K�F�\u0007�(P��\u0000ͤ����'\u0019�6��~�%��A*��;�E�:\u0005��/Jn3�\u0018x�k��\u001aF7�Nyk��ꬼ4�\u001d\u001aʩ��\u001f\u001a�z�߷��S�\u0001�@\u0006�0sBC�1a��E2����?֞ \u0008� X�\u0013��\u001c�\u0000\u000c\u0000\u0000,"The path: index.json was not found in artifact contents")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000
�Խ
�0\u0010\u0000��>E�\u0001һ��T�Ap�"*\u0008�\u0012l�
��V(���A\Z\�#�o�;����ݝ��Z�:/8!��Y��\u0008�j�/H��|\u0003\u0006R�\u0008s��;�q/J��V�X�\u0007y���$�3�\u0001PH\u0010\u0008\u000e~�#z#�;5�p��Ty�%Y�+~)�٫<m*\u001fz�V���uwD��\u001f<b(@�B\u0008����#<3������c\u001cm\u000e�u�8����x�\u001fx�,˲��=\u0001��y�\u0000\u000c\u0000\u0000,"'7' is an invalid end of a number. Expected a delimiter. Path: $.INVALID_JSON | LineNumber: 0 | BytePositionInLine: 20.")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000\u0003��K
�0\u0010\u0006�=EO��4�$��]z��\u0005\u001f4�>� ��t!�HqS\u001b�|�\u000c�L\u0018~��츭�j;.\u0014�������\u000c�O���~\u0001\u0006�\u0008\u0018���7	\u0018�޶~�5f���d�?�U�Z�4�\u0018�(�\u0004�\u001b_���0���X\u000e�⚛��qSC=�\u0010��I����5�S�\u0001
�\u0004Z\u0010i(��\u001f���_%�����#�\u0006I�$I\u000cO����\u0000\u000c\u0000\u0000,"The path: index.json was not found in artifact contents")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000\u0003���
�@\u0010\u0000�=�\u0014�\u000f����\u0015x\u0008:d�\u0005A�XR�@\u000b5\u0010z��CtQ��\u0013��qg`f\u0019f����:�qR��\u0017 \��\u0006�`���A�DT�\u0001\u0002�9G\u0008׽w��QV�0��Q�\u0007y
�*͒�J\u0001L1�(��������]1:�w]]�4���\�[ޤg]�S�����p5��?x\u000cQ\u000e��\�G\u0011\u0008n.\u0002£�����	��r\u001b�N��.r\u0016�\�{�,˲��\u0002\u0004��\u0000\u000c\u0000\u0000,"'7' is an invalid end of a number. Expected a delimiter. Path: $.INVALID_JSON | LineNumber: 0 | BytePositionInLine: 20.")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000\u0003���
�@\u0010\u0007�=�\u0014�\u000f���~h�KХ\u0007�t"#M\\u0003!z��\u0010]�.~\u0004��30�\u000c��ޛf�&�ʲ@�Z326h)!z�;\h��\u001b\u0010�RJBh3�&=�6U��\u001c�~�\u001fRSg9�\+\u0010�\u0008C�|�\u0014\u0007�jk�P�G�4�9Ί\u0014\u001bv���kχڗ��3�s��f|�?\u0004�p	:�R��	()�<�Y2����P�P`SbRc�������'s��\z7�q\u001cg:/��$I\u0000\u000c\u0000\u0000,"Value cannot be null. (Parameter 'source')")
Bicep.Core.IntegrationTests.DirectResourceCollectionTests ‑ DirectResourceCollectionAccess_NotAllowedWithinLoops ("output loopOutput array = [for i in range(0, 2): {
  prop: map(containerWorkers, (w) => w.properties.ipAddress.ip)
}]")
Bicep.Core.IntegrationTests.DirectResourceCollectionTests ‑ DirectResourceCollectionAccess_NotAllowedWithinLoops ("resource propertyLoop 'Microsoft.ContainerInstance/containerGroups@2022-09-01' = {
  name: 'gh9440-loop'
  location: 'westus'
  properties: {
    containers: [for i in range(0, 2): {
      name: 'gh9440-w1c-${i}'
      properties: {
        command: [
          'echo "${join(map(containerWorkers, (w) => w.properties.ipAddress.ip), ',')}"'
        ]
      }
    }]
  }
}")
Bicep.Core.IntegrationTests.DirectResourceCollectionTests ‑ DirectResourceCollectionAccess_NotAllowedWithinLoops ("var loopVar = [for i in range(0, 2): {
  prop: map(containerWorkers, (w) => w.properties.ipAddress.ip)
}]")
Bicep.Core.IntegrationTests.Emit.ParamsFileWriterTests ‑ Params_file_with_no_errors_should_compile_correctly ("
using 'main.bicep'

// involves all syntax
param myParam = {
  arr: [
    {
      a : 'b'
    }
    {
      c : true
    }
  ]
  name: 'complex object!'
  priority: 3
  val: null
  obj: {
      a: 'b'
      c: [
          'd'
           1
      ]
  }
}","
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentParameters.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "myParam": {
      "value": {
        "arr" : [
          {
            "a" : "b"
          },
          {
            "c" : true
          }
        ],
        "name" : "complex object!",
        "priority" : 3,
        "val" : null,
        "obj" : {
          "a" : "b",
          "c" : [
            "d",
            1
          ]
        }
      }
    }
  }
}","
param myParam object
")
…

♻️ This comment has been updated with latest results.

[Copilot]

Pull Request Overview

This PR introduces this().exists as an experimental feature for Bicep, allowing developers to conditionally modify resource properties based on whether the resource already exists during deployment. The feature requires explicit enablement through experimental flags and is restricted to resource property contexts only.

Key changes:

• Adds a new experimental feature flag thisExistsFunction with configuration support
• Implements the this() function that returns an object with an exists property
• Restricts usage to resource properties only, with proper validation and error handling

Reviewed Changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/vscode-bicep/schemas/bicepconfig.schema.json	Adds schema definition for the new thisExistsFunction experimental feature
src/Bicep.Core/Semantics/Namespaces/AzNamespaceType.cs	Implements the this() function with context validation and return type definition
src/Bicep.Core/Semantics/Namespaces/NamespaceProvider.cs	Passes feature provider to namespace creation for conditional function registration
src/Bicep.Core/Intermediate/	Adds new ThisFunctionExpression type and visitor pattern support
src/Bicep.Core/Emit/ExpressionConverter.cs	Converts this().exists to ARM template targetExists() function
src/Bicep.Core/Features/	Adds feature flag support across the feature provider infrastructure
src/Bicep.Core/Diagnostics/DiagnosticBuilder.cs	Adds error message for invalid usage contexts
src/Bicep.Core/Configuration/ExperimentalFeaturesEnabled.cs	Extends configuration to include the new experimental feature
Tests and documentation files	Comprehensive test coverage and documentation for the new feature

Comments suppressed due to low confidence (1)