When using a parameter with an imported user-defined type array, template compilation fails

[GABRIELNGBTUC]

Bicep version
Bicep CLI version 0.22.6 (d62b94d)
VS code extension was directly installed from the provided .vsix in the release tab from GitHub

Describe the bug
When upgrading to the 0.22.6, any template that has a parameter type CustomType[] where CustomType is imported now fails to compile

To Reproduce
main.bicep:

import {Foo} from 'types.bicep'

param foo Foo[] = [
  {
    bar: true
  }
  {
    bar: false
  }
]

types.bicep:

@export()
type Foo = {
  bar: bool
}

In 0.21.1, az bicep build -f main.bicep compiles to the following

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "languageVersion": "2.0",
  "contentVersion": "1.0.0.0",
  "metadata": {
    "_generator": {
      "name": "bicep",
      "version": "0.21.1.54444",
      "templateHash": "3487146124344436412"
    }
  },
  "definitions": {
    "Foo": {
      "type": "object",
      "properties": {
        "bar": {
          "type": "bool"
        }
      },
      "metadata": {
        "__bicep_imported_from!": {
          "sourceTemplate": "types.bicep"
        }
      }
    }
  },
  "parameters": {
    "foo": {
      "type": "array",
      "items": {
        "$ref": "#/definitions/Foo"
      },
      "defaultValue": [
        {
          "bar": true
        },
        {
          "bar": false
        }
      ]
    }
  },
  "resources": {}
}

In 0.22.6, running the same commands fails with the following error:

WARNING: The following experimental Bicep features have been enabled: Compile-time imports. Experimental features should be enabled for testing purposes only, as there are no guarantees about the quality or stability of these features. Do not enable these settings for any production usage, or your production environment may be subject to breaking.
Unhandled exception. System.ArgumentException: Invalid type expression encountered.
   at Bicep.Core.Emit.TemplateWriter.TypePropertiesForTypeExpression(TypeExpression typeExpression)
   at Bicep.Core.Emit.TemplateWriter.GetTypePropertiesForArrayType(ArrayTypeExpression expression)
   at Bicep.Core.Emit.TemplateWriter.TypePropertiesForTypeExpression(TypeExpression typeExpression)
   at Bicep.Core.Emit.TemplateWriter.<>c__DisplayClass27_0.<EmitParameter>b__0()
   at Bicep.Core.Emit.PositionTrackingJsonTextWriter.WriteObjectWithPosition(IPositionable sourcePosition, Action propertiesFunc)
   at Bicep.Core.Emit.ExpressionEmitter.EmitObject(Action writePropertiesFunc, IPositionable position)
   at Bicep.Core.Emit.ExpressionEmitter.<>c__DisplayClass32_0.<EmitObjectProperty>b__0()
   at Bicep.Core.Emit.PositionTrackingJsonTextWriter.WritePropertyWithPosition(IPositionable keyPosition, String name, Action valueFunc)
   at Bicep.Core.Emit.ExpressionEmitter.EmitProperty(String propertyName, Action writeValueFunc, IPositionable position)
   at Bicep.Core.Emit.ExpressionEmitter.EmitObjectProperty(String propertyName, Action writePropertiesFunc, IPositionable position)
   at Bicep.Core.Emit.TemplateWriter.EmitParameter(ExpressionEmitter emitter, DeclaredParameterExpression parameter)
   at Bicep.Core.Emit.TemplateWriter.<>c__DisplayClass23_0.<EmitParametersIfPresent>b__0()
   at Bicep.Core.Emit.PositionTrackingJsonTextWriter.WriteObjectWithPosition(IPositionable sourcePosition, Action propertiesFunc)
   at Bicep.Core.Emit.ExpressionEmitter.EmitObject(Action writePropertiesFunc, IPositionable position)
   at Bicep.Core.Emit.ExpressionEmitter.<>c__DisplayClass32_0.<EmitObjectProperty>b__0()
   at Bicep.Core.Emit.PositionTrackingJsonTextWriter.WritePropertyWithPosition(IPositionable keyPosition, String name, Action valueFunc)
   at Bicep.Core.Emit.ExpressionEmitter.EmitProperty(String propertyName, Action writeValueFunc, IPositionable position)
   at Bicep.Core.Emit.ExpressionEmitter.EmitObjectProperty(String propertyName, Action writePropertiesFunc, IPositionable position)
   at Bicep.Core.Emit.TemplateWriter.EmitParametersIfPresent(ExpressionEmitter emitter, ImmutableArray`1 parameters)
   at Bicep.Core.Emit.TemplateWriter.GenerateTemplateWithoutHash(PositionTrackingJsonTextWriter jsonWriter)
   at Bicep.Core.Emit.TemplateWriter.Write(SourceAwareJsonTextWriter writer)
   at Bicep.Core.Emit.TemplateEmitter.<>c__DisplayClass10_0.<Emit>b__0()
   at Bicep.Core.Emit.TemplateEmitter.EmitOrFail(Func`1 write)
   at Bicep.Core.Emit.TemplateEmitter.Emit(TextWriter textWriter)
   at Bicep.Core.Emit.TemplateEmitter.Emit(Stream stream)
   at Bicep.Cli.Services.CompilationWriter.ToStream(SemanticModel model, Stream stream)
   at Bicep.Cli.Services.CompilationWriter.ToFile(SemanticModel model, String outputPath)
   at Bicep.Cli.Services.CompilationWriter.ToFile(Compilation compilation, String outputPath)
   at Bicep.Cli.Commands.BuildCommand.RunAsync(BuildArguments args)
   at Bicep.Cli.Program.RunAsync(String[] args)
   at Bicep.Cli.Program.Main(String[] args)
   at Bicep.Cli.Program.<Main>(String[] args)

[GABRIELNGBTUC]

I started compiling more templates where non array custom types are defined and they are failing as well.

The sample modified to the following is also failing:

import {Foo} from 'types.bicep'

param foo Foo = {
  bar: false
}

v0.21.1:

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "metadata": {
    "_generator": {
      "name": "bicep",
      "version": "0.21.1.54444",
      "templateHash": "13878968526056156201"
    }
  },
  "definitions": {
    "Foo": {
      "type": "object",
      "properties": {
        "bar": {
          "type": "bool"
        }
      },
      "metadata": {
        "__bicep_imported_from!": {
          "sourceTemplate": "types.bicep"
        }
      }
    }
  },
  "parameters": {
    "foo": {
      "$ref": "#/definitions/Foo",
      "defaultValue": {
        "bar": false
      }
    }
  },
  "resources": []
}

v0.22.6:

WARNING: The following experimental Bicep features have been enabled: User-defined functions, Compile-time imports. Experimental features should be enabled for testing purposes only, as there are no guarantees about the quality or stability of these features. Do not enable these settings for any production usage, or your production environment may be subject to breaking.
Unhandled exception. System.ArgumentException: Invalid type expression encountered.
   at Bicep.Core.Emit.TemplateWriter.TypePropertiesForTypeExpression(TypeExpression typeExpression)
   at Bicep.Core.Emit.TemplateWriter.<>c__DisplayClass61_0.<EmitOutput>b__0()
   at Bicep.Core.Emit.PositionTrackingJsonTextWriter.WriteObjectWithPosition(IPositionable sourcePosition, Action propertiesFunc)
   at Bicep.Core.Emit.ExpressionEmitter.EmitObject(Action writePropertiesFunc, IPositionable position)
   at Bicep.Core.Emit.ExpressionEmitter.<>c__DisplayClass32_0.<EmitObjectProperty>b__0()
   at Bicep.Core.Emit.PositionTrackingJsonTextWriter.WritePropertyWithPosition(IPositionable keyPosition, String name, Action valueFunc)
   at Bicep.Core.Emit.ExpressionEmitter.EmitProperty(String propertyName, Action writeValueFunc, IPositionable position)
   at Bicep.Core.Emit.ExpressionEmitter.EmitObjectProperty(String propertyName, Action writePropertiesFunc, IPositionable position)
   at Bicep.Core.Emit.TemplateWriter.EmitOutput(ExpressionEmitter emitter, DeclaredOutputExpression output)
   at Bicep.Core.Emit.TemplateWriter.<>c__DisplayClass60_0.<EmitOutputsIfPresent>b__0()
   at Bicep.Core.Emit.PositionTrackingJsonTextWriter.WriteObjectWithPosition(IPositionable sourcePosition, Action propertiesFunc)
   at Bicep.Core.Emit.ExpressionEmitter.EmitObject(Action writePropertiesFunc, IPositionable position)
   at Bicep.Core.Emit.ExpressionEmitter.<>c__DisplayClass32_0.<EmitObjectProperty>b__0()
   at Bicep.Core.Emit.PositionTrackingJsonTextWriter.WritePropertyWithPosition(IPositionable keyPosition, String name, Action valueFunc)
   at Bicep.Core.Emit.ExpressionEmitter.EmitProperty(String propertyName, Action writeValueFunc, IPositionable position)
   at Bicep.Core.Emit.ExpressionEmitter.EmitObjectProperty(String propertyName, Action writePropertiesFunc, IPositionable position)
   at Bicep.Core.Emit.TemplateWriter.EmitOutputsIfPresent(ExpressionEmitter emitter, ImmutableArray`1 outputs)
   at Bicep.Core.Emit.TemplateWriter.GenerateTemplateWithoutHash(PositionTrackingJsonTextWriter jsonWriter)
   at Bicep.Core.Emit.TemplateWriter.Write(SourceAwareJsonTextWriter writer)
   at Bicep.Core.Emit.TemplateEmitter.<>c__DisplayClass10_0.<Emit>b__0()
   at Bicep.Core.Emit.TemplateEmitter.EmitOrFail(Func`1 write)
   at Bicep.Core.Emit.TemplateEmitter.Emit(TextWriter textWriter)
   at Bicep.Core.Emit.TemplateEmitter.Emit(Stream stream)
   at Bicep.Cli.Services.CompilationWriter.ToStream(SemanticModel model, Stream stream)
   at Bicep.Cli.Services.CompilationWriter.ToFile(SemanticModel model, String outputPath)
   at Bicep.Cli.Services.CompilationWriter.ToFile(Compilation compilation, String outputPath)
   at Bicep.Cli.Commands.BuildCommand.RunAsync(BuildArguments args)
   at Bicep.Cli.Program.RunAsync(String[] args)
   at Bicep.Cli.Program.Main(String[] args)
   at Bicep.Cli.Program.<Main>(String[] args)

If the Foo type is defined in the main.bicep the template compiles successfully.

[jeskew]

Thanks for reporting, @GABRIELNGBTUC! This reflected a gap in the test coverage for type imports that should be addressed by the linked PR.

If this bug is blocking you from executing needed deployments, there is a workaround you can use. The underlying issue will cause the error you encountered when an imported type is used in a param or output statement, but imported types in type statements are handled. You can therefore use an extra type statement to unblock your deployment:

import {Foo} from 'types.bicep'

type myFoo = Foo // <-- creating an alias for use in param and output statements avoids the issue
param foo myFoo = {
  bar: false
}