Preserve source text for float literals in CAST expressions

- Add Source field to ast.Literal to store original source text
- Set Source field when parsing decimal float literals
- Use Source field in formatExprAsString for CAST operator syntax
- This preserves "0.0" instead of outputting "0" for zero floats

Fixes iceberg_bucket and other tests with float casting.

Author: claude

ast/ast.go

@@ -1079,6 +1079,7 @@ type Literal struct {
 	Position token.Position `json:"-"`
 	Type     LiteralType    `json:"type"`
 	Value    interface{}    `json:"value"`
+	Source   string         `json:"source,omitempty"`   // Original source text (for preserving 0.0 vs 0)
 	Negative bool           `json:"negative,omitempty"` // True if literal was explicitly negative (for -0)
 }
 

internal/explain/format.go

@@ -374,6 +374,10 @@ func formatExprAsString(expr ast.Expression) string {
 			}
 			return fmt.Sprintf("%d", e.Value)
 		case ast.LiteralFloat:
+			// Use Source field if available to preserve original representation (e.g., "0.0")
+			if e.Source != "" {
+				return e.Source
+			}
 			if e.Negative {
 				switch v := e.Value.(type) {
 				case float64:

parser/expression.go

@@ -751,6 +751,7 @@ func (p *Parser) parseNumber() ast.Expression {
 		} else {
 			lit.Type = ast.LiteralFloat
 			lit.Value = f
+			lit.Source = value // Preserve original source text (e.g., "0.0" vs "0")
 		}
 	} else if isHexFloat {
 		// Parse hex float (Go doesn't support this directly, approximate)
@@ -860,6 +861,7 @@ func (p *Parser) parseUnaryMinus() ast.Expression {
 			f, _ := strconv.ParseFloat(numVal, 64)
 			lit.Type = ast.LiteralFloat
 			lit.Value = f
+			lit.Source = numVal // Preserve original source text
 		} else {
 			i, _ := strconv.ParseInt(numVal, 10, 64)
 			lit.Value = i

parser/testdata/02009_decimal_no_trailing_zeros/metadata.json

@@ -1,14 +1 @@
-{
-  "explain_todo": {
-    "stmt11": true,
-    "stmt12": true,
-    "stmt13": true,
-    "stmt14": true,
-    "stmt15": true,
-    "stmt27": true,
-    "stmt28": true,
-    "stmt29": true,
-    "stmt30": true,
-    "stmt31": true
-  }
-}
+{}

parser/testdata/02124_comparison_betwwen_decimal_and_float/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt18": true
-  }
-}
+{}

parser/testdata/02155_binary_op_between_float_and_decimal/metadata.json

@@ -1 +1 @@
-{"explain_todo":{"stmt10":true,"stmt11":true,"stmt9":true}}
+{}

parser/testdata/02560_count_digits/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt14": true
-  }
-}
+{}

parser/testdata/02685_decimal256_various/metadata.json

@@ -1,18 +1,11 @@
 {
   "explain_todo": {
-    "stmt10": true,
     "stmt27": true,
     "stmt30": true,
     "stmt31": true,
     "stmt32": true,
     "stmt33": true,
     "stmt34": true,
-    "stmt35": true,
-    "stmt4": true,
-    "stmt5": true,
-    "stmt6": true,
-    "stmt7": true,
-    "stmt8": true,
-    "stmt9": true
+    "stmt35": true
   }
 }

parser/testdata/02841_parquet_filter_pushdown/metadata.json

@@ -1,10 +1,5 @@
 {
   "explain_todo": {
-    "stmt24": true,
-    "stmt25": true,
-    "stmt26": true,
-    "stmt31": true,
-    "stmt32": true,
-    "stmt33": true
+    "stmt26": true
   }
 }

parser/testdata/02892_orc_filter_pushdown/metadata.json

@@ -1,14 +1,6 @@
 {
   "explain_todo": {
-    "stmt38": true,
-    "stmt39": true,
-    "stmt40": true,
-    "stmt41": true,
     "stmt42": true,
-    "stmt43": true,
-    "stmt52": true,
-    "stmt53": true,
-    "stmt54": true,
-    "stmt55": true
+    "stmt43": true
   }
 }