8038182: javac crash with FunctionDescriptorLookupError for invalid functional interface

Co-authored-by: Maurizio Cimadamore <maurizio.cimadamore@oracle.com>
Reviewed-by: mcimadamore

langtools/src/share/classes/com/sun/tools/javac/code/Types.java

@@ -626,7 +626,7 @@ public class Types {
      * (ii) perform functional interface bridge calculation.
      */
     public ClassSymbol makeFunctionalInterfaceClass(Env<AttrContext> env, Name name, List<Type> targets, long cflags) {
-        if (targets.isEmpty() || !isFunctionalInterface(targets.head)) {
+        if (targets.isEmpty()) {
             return null;
         }
         Symbol descSym = findDescriptorSymbol(targets.head.tsym);

langtools/src/share/classes/com/sun/tools/javac/comp/Attr.java

@@ -3135,11 +3135,20 @@ public class Attr extends JCTree.Visitor {
             if (checkContext.deferredAttrContext().mode == DeferredAttr.AttrMode.CHECK &&
                     pt != Type.recoveryType) {
                 //check that functional interface class is well-formed
+                try {
+                    /* Types.makeFunctionalInterfaceClass() may throw an exception
+                     * when it's executed post-inference. See the listener code
+                     * above.
+                     */
                     ClassSymbol csym = types.makeFunctionalInterfaceClass(env,
                             names.empty, List.of(fExpr.targets.head), ABSTRACT);
                     if (csym != null) {
                         chk.checkImplementations(env.tree, csym, csym);
                     }
+                } catch (Types.FunctionDescriptorLookupError ex) {
+                    JCDiagnostic cause = ex.getDiagnostic();
+                    resultInfo.checkContext.report(env.tree, cause);
+                }
             }
         }
     }

langtools/test/tools/javac/lambda/T8038182/CrashFunctionDescriptorExceptionTest.java

@@ -0,0 +1,24 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8038182
+ * @summary javac crash with FunctionDescriptorLookupError for invalid functional interface
+ * @compile/fail/ref=CrashFunctionDescriptorExceptionTest.out -XDrawDiagnostics CrashFunctionDescriptorExceptionTest.java
+ */
+
+class CrashFunctionDescriptorExceptionTest {
+
+    @SuppressWarnings("unchecked")
+    void m () {
+        bar((B b) -> {});
+    }
+
+    <E extends A<E>> void bar(I<E> i) {}
+
+    class A<E> {}
+
+    class B<E> extends A<E> {}
+
+    interface I<E extends A<E>> {
+        void foo(E e);
+    }
+}

langtools/test/tools/javac/lambda/T8038182/CrashFunctionDescriptorExceptionTest.out

@@ -0,0 +1,2 @@
+CrashFunctionDescriptorExceptionTest.java:12:13: compiler.err.prob.found.req: (compiler.misc.no.suitable.functional.intf.inst: CrashFunctionDescriptorExceptionTest.I<CrashFunctionDescriptorExceptionTest.B>)
+1 error