fix(hcl): coerce non-string object keys to strings instead of panicking (#2795)

HCL object keys may be non-string literals (e.g. a number like 1). The
decoder called cty.Value.AsString on the evaluated key, which panics with
'not a string' for any non-string key type. Mirror OpenTofu/Terragrunt by
silently converting non-string keys to their string representation via
cty/convert. Add decode scenarios covering numeric and boolean keys.

pkg/yqlib/decoder_hcl.go

@@ -13,6 +13,7 @@ import (
 	"github.com/hashicorp/hcl/v2"
 	"github.com/hashicorp/hcl/v2/hclsyntax"
 	"github.com/zclconf/go-cty/cty"
+	"github.com/zclconf/go-cty/cty/convert"
 )
 
 type hclDecoder struct {
@@ -252,6 +253,22 @@ func addBlockToMapping(parent *CandidateNode, block *hclsyntax.Block, src []byte
 	}
 }
 
+// hclKeyValueAsString converts an evaluated HCL key expression to its string
+// representation. HCL object keys may be non-string literals (e.g. a number
+// like `1`); calling AsString on those panics. Mirroring OpenTofu/Terragrunt,
+// we silently coerce non-string keys to their string form ("1" -> "1",
+// true -> "true") instead of panicking.
+func hclKeyValueAsString(keyVal cty.Value) (string, error) {
+	if keyVal.Type() == cty.String {
+		return keyVal.AsString(), nil
+	}
+	strVal, err := convert.Convert(keyVal, cty.String)
+	if err != nil {
+		return "", err
+	}
+	return strVal.AsString(), nil
+}
+
 func convertHclExprToNode(expr hclsyntax.Expression, src []byte) *CandidateNode {
 	// handle literal values directly
 	switch e := expr.(type) {
@@ -338,7 +355,19 @@ func convertHclExprToNode(expr hclsyntax.Expression, src []byte) *CandidateNode
 				}
 				continue
 			}
-			keyStr := keyVal.AsString()
+			keyStr, err := hclKeyValueAsString(keyVal)
+			if err != nil {
+				// fallback: try to extract key from source
+				r := item.KeyExpr.Range()
+				start := r.Start.Byte
+				end := r.End.Byte
+				if start >= 0 && end >= start && end <= len(src) {
+					keyNode := createStringScalarNode(strings.TrimSpace(string(src[start:end])))
+					valNode := convertHclExprToNode(item.ValueExpr, src)
+					m.AddKeyValueChild(keyNode, valNode)
+				}
+				continue
+			}
 			keyNode := createStringScalarNode(keyStr)
 			valNode := convertHclExprToNode(item.ValueExpr, src)
 			m.AddKeyValueChild(keyNode, valNode)

pkg/yqlib/hcl_test.go

@@ -472,6 +472,20 @@ var hclFormatScenarios = []formatScenario{
 		expected:     "service {\n  optional_field = null\n}\n",
 		scenarioType: "roundtrip",
 	},
+	{
+		description:  "Non-string object keys are coerced to strings",
+		skipDoc:      true,
+		input:        `intdict = { 1 = {} }`,
+		expected:     "intdict: {\"1\": {}}\n",
+		scenarioType: "decode",
+	},
+	{
+		description:  "Mixed non-string object keys are coerced to strings",
+		skipDoc:      true,
+		input:        `d = { 1 = "a", 2 = "b", true = "c" }`,
+		expected:     "d: {\"1\": \"a\", \"2\": \"b\", \"true\": \"c\"}\n",
+		scenarioType: "decode",
+	},
 }
 
 func testHclScenario(t *testing.T, s formatScenario) {