ext/userfunc: use bare identifiers for param names

Now that we have the necessary functions to deal with this in the
low-level HCL API, it's more intuitive to use bare identifiers for these
parameter names. This reinforces the idea that they are symbols being
defined rather than arbitrary string expressions.

cmd/hcldec/spec-format.md

@@ -364,7 +364,7 @@ block type:
 
 ```
 function "add_one" {
- params = ["n"]
+ params = [n]
  result = n + 1
 }
 ```
@@ -379,9 +379,15 @@ input file:
 
 ```
 function "upper" {
- params = ["str"]
+ params = [str]
  result = upper(str)
 }
+
+function "min" {
+ params = []
+ variadic_param = nums
+ result = min(nums...)
+}
 ```
 
 Custom functions defined in the spec cannot be called from the spec itself.

ext/userfunc/README.md

@@ -7,9 +7,15 @@ Functions are defined via a specific block type, like this:
 
 ```hcl
 function "add" {
- params = ["a", "b"]
+ params = [a, b]
  result = a + b
 }
+
+function "list" {
+ params = []
+ variadic_param = items
+ result = items
+}
 ```
 
 The extension is implemented as a pre-processor for `cty.Body` objects. Given

ext/userfunc/decode.go

@@ -1,7 +1,6 @@
 package userfunc
 
 import (
- "github.com/hashicorp/hcl2/gohcl"
  "github.com/hashicorp/hcl2/hcl"
  "github.com/zclconf/go-cty/cty"
  "github.com/zclconf/go-cty/cty/function"
@@ -54,6 +53,7 @@ func decodeUserFunctions(body hcl.Body, blockType string, contextFunc ContextFun
  }
 
  funcs = make(map[string]function.Function)
+Blocks:
  for _, block := range content.Blocks {
  name := block.Labels[0]
  funcContent, funcDiags := block.Body.Content(funcBodySchema)
@@ -72,15 +72,34 @@ func decodeUserFunctions(body hcl.Body, blockType string, contextFunc ContextFun
  var params []string
  var varParam string
 
- paramsDiags := gohcl.DecodeExpression(paramsExpr, nil, &params)
+ paramExprs, paramsDiags := hcl.ExprList(paramsExpr)
  diags = append(diags, paramsDiags...)
  if paramsDiags.HasErrors() {
  continue
  }
+ for _, paramExpr := range paramExprs {
+ param := hcl.ExprAsKeyword(paramExpr)
+ if param == "" {
+ diags = append(diags, &hcl.Diagnostic{
+ Severity: hcl.DiagError,
+ Summary: "Invalid param element",
+ Detail: "Each parameter name must be an identifier.",
+ Subject: paramExpr.Range().Ptr(),
+ })
+ continue Blocks
+ }
+ params = append(params, param)
+ }
+
  if varParamExpr != nil {
- paramsDiags := gohcl.DecodeExpression(varParamExpr, nil, &varParam)
- diags = append(diags, paramsDiags...)
- if paramsDiags.HasErrors() {
+ varParam = hcl.ExprAsKeyword(varParamExpr)
+ if varParam == "" {
+ diags = append(diags, &hcl.Diagnostic{
+ Severity: hcl.DiagError,
+ Summary: "Invalid variadic_param",
+ Detail: "The variadic parameter name must be an identifier.",
+ Subject: varParamExpr.Range().Ptr(),
+ })
  continue
  }
  }

ext/userfunc/decode_test.go

@@ -4,8 +4,8 @@ import (
  "fmt"
  "testing"
 
- "github.com/hashicorp/hcl2/hcl/hclsyntax"
  "github.com/hashicorp/hcl2/hcl"
+ "github.com/hashicorp/hcl2/hcl/hclsyntax"
  "github.com/zclconf/go-cty/cty"
 )
 
@@ -20,7 +20,7 @@ func TestDecodeUserFunctions(t *testing.T) {
  {
  `
 function "greet" {
- params = ["name"]
+ params = [name]
  result = "Hello, ${name}."
 }
 `,
@@ -32,7 +32,7 @@ function "greet" {
  {
  `
 function "greet" {
- params = ["name"]
+ params = [name]
  result = "Hello, ${name}."
 }
 `,
@@ -44,7 +44,7 @@ function "greet" {
  {
  `
 function "greet" {
- params = ["name"]
+ params = [name]
  result = "Hello, ${name}."
 }
 `,
@@ -56,7 +56,7 @@ function "greet" {
  {
  `
 function "add" {
- params = ["a", "b"]
+ params = [a, b]
  result = a + b
 }
 `,
@@ -69,7 +69,7 @@ function "add" {
  `
 function "argstuple" {
  params = []
- variadic_param = "args"
+ variadic_param = args
  result = args
 }
 `,
@@ -109,11 +109,11 @@ function "closure" {
  {
  `
 function "neg" {
- params = ["val"]
+ params = [val]
  result = -val
 }
 function "add" {
- params = ["a", "b"]
+ params = [a, b]
  result = a + b
 }
 `,
@@ -125,7 +125,7 @@ function "add" {
  {
  `
 function "neg" {
- parrams = ["val"]
+ parrams = [val]
  result = -val
 }
 `,