Fix cfg exceptions around empty statement lists

Author: jgardn3r

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Exceptions from empty structures (e.g., `if`) in `LoopExecutingAtMostOnce` and `RedundantJump`.
+
 ## [1.14.1] - 2025-03-05
 
 ### Fixed

delphi-frontend/src/main/java/au/com/integradev/delphi/cfg/api/Branch.java

@@ -18,6 +18,8 @@
  */
 package au.com.integradev.delphi.cfg.api;
 
+import java.util.Collections;
+import java.util.HashSet;
 import java.util.Set;
 
 /** A block where the control flow is dictated by a boolean condition, e.g., {@code if} */
@@ -38,6 +40,9 @@ public interface Branch extends Block, Terminated {
 
   @Override
   default Set<Block> getSuccessors() {
-    return Set.of(getTrueBlock(), getFalseBlock());
+    Set<Block> successors = new HashSet<>();
+    successors.add(getTrueBlock());
+    successors.add(getFalseBlock());
+    return Collections.unmodifiableSet(successors);
   }
 }

delphi-frontend/src/test/java/au/com/integradev/delphi/cfg/ControlFlowGraphTest.java

@@ -317,6 +317,28 @@ void testIfAnd() {
             block(element(NameReferenceNode.class, "Foo")).succeedsTo(0)));
   }
 
+  @Test
+  void testEmptyIf() {
+    test(
+        "if C then begin end; A;",
+        checker(
+            block(element(NameReferenceNode.class, "C"))
+                .branchesTo(1, 1)
+                .withTerminator(IfStatementNode.class),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
+  @Test
+  void testEmptyIfElse() {
+    test(
+        "if C then begin end else begin end; A;",
+        checker(
+            block(element(NameReferenceNode.class, "C"))
+                .branchesTo(1, 1)
+                .withTerminator(IfStatementNode.class),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
   @Test
   void testLocalVarDeclaration() {
     test(
@@ -421,6 +443,42 @@ void testCaseStatementElse() {
                 .succeedsToCases(2, 3, 4)));
   }
 
+  @Test
+  void testEmptyCase() {
+    test(
+        "case S of end; A;",
+        checker(
+            block(element(NameReferenceNode.class, "S"))
+                .withTerminator(CaseStatementNode.class)
+                .succeedsToCases(1),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
+  @Test
+  void testEmptyCaseElse() {
+    test(
+        "case S of else end; A;",
+        checker(
+            block(element(NameReferenceNode.class, "S"))
+                .withTerminator(CaseStatementNode.class)
+                .succeedsToCases(1),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
+  @Test
+  void testEmptyCaseArm() {
+    test(
+        "case S of S1:; S2:; end; A;",
+        checker(
+            block(
+                    element(NameReferenceNode.class, "S"),
+                    element(NameReferenceNode.class, "S1"),
+                    element(NameReferenceNode.class, "S2"))
+                .withTerminator(CaseStatementNode.class)
+                .succeedsToCases(1, 1),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
   @Test
   void testRepeat() {
     test(
@@ -457,6 +515,17 @@ void testRepeatBreak() {
                 .withTerminator(RepeatStatementNode.class)));
   }
 
+  @Test
+  void testEmptyRepeat() {
+    test(
+        "repeat until C; A;",
+        checker(
+            block(element(NameReferenceNode.class, "C"))
+                .branchesTo(1, 2)
+                .withTerminator(RepeatStatementNode.class),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
   @Test
   void testWhile() {
     test(
@@ -493,6 +562,17 @@ void testWhileBreak() {
                 .withTerminator(StatementTerminator.BREAK)));
   }
 
+  @Test
+  void testEmptyWhile() {
+    test(
+        "while C do; A;",
+        checker(
+            block(element(NameReferenceNode.class, "C"))
+                .branchesTo(2, 1)
+                .withTerminator(WhileStatementNode.class),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
   @Test
   void testForToVarDecl() {
     test(
@@ -585,6 +665,19 @@ void testForToConditionalContinue() {
                 .withTerminator(ForToStatementNode.class)));
   }
 
+  @Test
+  void testEmptyForTo() {
+    test(
+        "for I := F to T do; A;",
+        checker(
+            block(element(NameReferenceNode.class, "F")).succeedsTo(3),
+            block(element(NameReferenceNode.class, "T")).succeedsTo(2),
+            block(element(NameReferenceNode.class, "I"))
+                .branchesTo(2, 1)
+                .withTerminator(ForToStatementNode.class),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
   @Test
   void testForInVarDecl() {
     test(
@@ -671,6 +764,18 @@ void testForInConditionalContinue() {
                 .withTerminator(ForInStatementNode.class)));
   }
 
+  @Test
+  void testEmptyForIn() {
+    test(
+        "for I in C do; A;",
+        checker(
+            block(element(NameReferenceNode.class, "C")).succeedsTo(2),
+            block(element(NameReferenceNode.class, "I"))
+                .branchesTo(2, 1)
+                .withTerminator(ForInStatementNode.class),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
   @Test
   void testBreakOutsideOfLoop() {
     GraphChecker checker = checker();
@@ -696,6 +801,15 @@ void testWith() {
             block(element(NameReferenceNode.class, "Foo")).succeedsTo(0)));
   }
 
+  @Test
+  void testEmptyWith() {
+    test(
+        "with S do; A;",
+        checker(
+            block(element(NameReferenceNode.class, "S")).succeedsTo(1),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
   @Test
   void testTryFinallyNoRaise() {
     test(
@@ -1074,6 +1188,25 @@ void testTryExceptReRaise() {
                 .succeedsToWithExceptions(0)));
   }
 
+  @Test
+  void testEmptyTryExcept() {
+    test(
+        "try except end; A",
+        checker(
+            block(element(TryStatementNode.class)).succeedsTo(1),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
+  @Test
+  void testEmptyTryFinally() {
+    test(
+        "try finally end; A",
+        checker(
+            block(element(TryStatementNode.class)).succeedsTo(2),
+            block().succeedsToWithExit(1, 0),
+            block(element(NameReferenceNode.class, "A")).succeedsTo(0)));
+  }
+
   @Test
   void testRaiseOutsideTry() {
     test(
@@ -1320,6 +1453,14 @@ void testLabelSeparatesBlock() {
                 .jumpsTo(2, 0)));
   }
 
+  @Test
+  void testEmptyLabel() {
+    test(
+        Map.of("label", List.of("A,B")),
+        "A: B: C;",
+        checker(block(element(NameReferenceNode.class, "C")).succeedsTo(0)));
+  }
+
   @Test
   void testAnonymousRoutinesAreIgnored() {
     test(