Merge pull request #42166 from mindula/fix-crash

Fix compiler crash caused by functions with infinite while loops

compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/bir/BIRGen.java

@@ -747,6 +747,7 @@ public void visit(BLangBlockFunctionBody astBody) {
         }
         this.env.enclLoopEndBB = endLoopEndBB;
         this.currentBlock = prevBlock;
+        addReturnBB(astBody.pos);
     }
 
     private BIRBasicBlock beginBreakableBlock(BLangBlockStmt.FailureBreakMode mode) {
@@ -1392,15 +1393,9 @@ public void visit(BLangReturn astReturnStmt) {
         BIROperand retVarRef = new BIROperand(this.env.enclFunc.returnVariable);
         setScopeAndEmit(new Move(astReturnStmt.pos, this.env.targetOperand, retVarRef));
 
-        // Check whether this function already has a returnBB.
+        // Check and add a returnBB if the function does not have a returnBB.
         // A given function can have only one BB that has a return instruction.
-        if (this.env.returnBB == null) {
-            // If not create one
-            BIRBasicBlock returnBB = new BIRBasicBlock(this.env.nextBBId());
-            addToTrapStack(returnBB);
-            returnBB.terminator = new BIRTerminator.Return(getFunctionLastLinePos());
-            this.env.returnBB = returnBB;
-        }
+        addReturnBB(getFunctionLastLinePos());
         if (this.env.enclBB.terminator == null) {
             this.env.unlockVars.forEach(s -> {
                 int i = s.size();
@@ -1438,12 +1433,7 @@ private BLangDiagnosticLocation getFunctionLastLinePos() {
     public void visit(BLangPanic panicNode) {
         panicNode.expr.accept(this);
         // Some functions will only have panic but we need to add return for them to make current algorithm work.
-        if (this.env.returnBB == null) {
-            BIRBasicBlock returnBB = new BIRBasicBlock(this.env.nextBBId());
-            addToTrapStack(returnBB);
-            returnBB.terminator = new BIRTerminator.Return(panicNode.pos);
-            this.env.returnBB = returnBB;
-        }
+        addReturnBB(panicNode.pos);
         this.env.enclBB.terminator = new BIRTerminator.Panic(panicNode.pos, this.env.targetOperand, this.currentScope);
 
         // This basic block will contain statement that comes right after this 'if' statement.
@@ -3059,4 +3049,13 @@ private BIRVariableDcl getAnnotations(BVarSymbol annotations, BIRGenEnv env) {
         }
         return globalVarMap.get(annotations);
     }
+
+    private void addReturnBB(Location pos) {
+        if (this.env.returnBB == null) {
+            BIRBasicBlock returnBB = new BIRBasicBlock(this.env.nextBBId());
+            addToTrapStack(returnBB);
+            returnBB.terminator = new BIRTerminator.Return(pos);
+            this.env.returnBB = returnBB;
+        }
+    }
 }

tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/statements/whilestatement/WhileStmtTest.java

@@ -244,6 +244,12 @@ public void testNestedWhileStmtLoopTerminationWithFail() {
         Assert.assertEquals(actual, expected);
     }
 
+    @Test(description = "Test while statement with infinite loop")
+    public void testWhileStmtWithEndlessLoop() {
+        CompileResult compiled = BCompileUtil.compile("test-src/statements/whilestatement/while-stmt-infinite.bal");
+        Assert.assertEquals(compiled.getErrorCount(), 0);
+    }
+
     @Test(description = "Check incompatible types.")
     public void testNegative1() {
         int index = 0;

tests/jballerina-unit-test/src/test/resources/test-src/statements/whilestatement/while-stmt-infinite.bal

@@ -0,0 +1,81 @@
+const TRUE = true;
+
+function testWhileStatementWithEndlessLoop() returns int {
+   int x = 1;
+   while true {
+      x += 1;
+   }
+}
+
+function testWhileStatementWithEndlessLoop2() returns int|never {
+   int x = 1;
+   while TRUE {
+      x += 1;
+   }
+}
+
+function testWhileStatementWithEndlessLoop3() returns int {
+   int x = 1;
+   while true {
+      while true {
+         while true {
+            x += 1;
+         }
+      }
+   }
+}
+
+function testWhileStatementWithEndlessLoop4() returns int {
+   int x = 0;
+   while true {
+     x += 1;
+     if (x == 50) {
+        // Intentionally no break statement
+     }
+   }
+}
+
+function testInfiniteLoopWhileStatementInWorker() returns future<int> {
+    worker name returns int {
+        while true {
+
+        }
+    }
+    return name;
+}
+
+function testInfiniteLoopWhileStatementInAnonymousFunction() {
+    function() returns int fn = function () returns int {
+        while true {
+
+        }
+    };
+    _ = fn();
+}
+
+
+function testInfiniteLoopWhileStatementInConditionalStatement(int x) returns int {
+    if x > 10 {
+        while true {
+
+        }
+    } else {
+        while true {
+
+        }
+    }
+}
+
+client class MyClientClass {
+    resource function accessor path() returns int {
+        while true {
+
+        }
+    }
+
+    remote function testInfiniteLoopWhileStatementInRemote() returns int {
+        while true {
+
+        }
+    }
+}