Fix double unary minus (#697)

Fix an issue where doubly unary minus (e.g. `--1`) on int/float literals are incorrectly
parsed as single unary minus.

pkl-core/src/main/java/org/pkl/core/ast/builder/AstBuilder.java

@@ -1869,12 +1869,12 @@ public final class AstBuilder extends AbstractAstBuilder<Object> {
 
   @Override
   public ExpressionNode visitUnaryMinusExpr(UnaryMinusExprContext ctx) {
-    var childExpr = visitExpr(ctx.expr());
-    if (childExpr instanceof IntLiteralNode || childExpr instanceof FloatLiteralNode) {
-      // negation already handled in child expr (see corresponding code)
+    var childCtx = ctx.expr();
+    var childExpr = visitExpr(childCtx);
+    if (childCtx instanceof IntLiteralContext || childCtx instanceof FloatLiteralContext) {
+      // negation already handled (see visitIntLiteral/visitFloatLiteral)
       return childExpr;
     }
-
     return UnaryMinusNodeGen.create(createSourceSection(ctx), childExpr);
   }
 

pkl-core/src/test/files/LanguageSnippetTests/input/basic/float.pkl

@@ -141,6 +141,10 @@ examples {
 
     -1.2.abs
     -x.abs
+
+    // https://github.com/apple/pkl/issues/650
+    --1.0
+    -(-1.0)
   }
 
   ["power"] {

pkl-core/src/test/files/LanguageSnippetTests/input/basic/int.pkl

@@ -163,6 +163,10 @@ examples {
     -0b11.abs
     local x = 4
     -x.abs
+
+    // https://github.com/apple/pkl/issues/650
+    --1
+    -(-1)
   }
 
   ["power"] {

pkl-core/src/test/files/LanguageSnippetTests/output/basic/float.pcf

@@ -98,6 +98,8 @@ examples {
   ["negation"] {
     -1.2
     -1.2
+    1.0
+    1.0
   }
   ["power"] {
     27.98409999999999

pkl-core/src/test/files/LanguageSnippetTests/output/basic/int.pcf

@@ -121,6 +121,8 @@ examples {
     -2
     -3
     -4
+    1
+    1
   }
   ["power"] {
     16