7039937: Improved catch analysis fails to handle a common idiom in the libraries

Summary: Disable generation of 'unreachable catch' warnings for catch statements catching Exception/Throwable
Reviewed-by: jjg

src/share/classes/com/sun/tools/javac/comp/Flow.java

@@ -1153,8 +1153,7 @@ public class Flow extends TreeScanner {
         if (chk.subset(exc, caughtInTry)) {
             log.error(pos, "except.already.caught", exc);
         } else if (!chk.isUnchecked(pos, exc) &&
-                exc.tsym != syms.throwableType.tsym &&
-                exc.tsym != syms.exceptionType.tsym &&
+                !isExceptionOrThrowable(exc) &&
                 !chk.intersects(exc, thrownInTry)) {
             log.error(pos, "except.never.thrown.in.try", exc);
         } else if (allowImprovedCatchAnalysis) {
@@ -1163,7 +1162,8 @@ public class Flow extends TreeScanner {
             // unchecked exception, the result list would not be empty, as the augmented
             // thrown set includes { RuntimeException, Error }; if 'exc' was a checked
             // exception, that would have been covered in the branch above
-            if (chk.diff(catchableThrownTypes, caughtInTry).isEmpty()) {
+            if (chk.diff(catchableThrownTypes, caughtInTry).isEmpty() &&
+                    !isExceptionOrThrowable(exc)) {
                 String key = catchableThrownTypes.length() == 1 ?
                         "unreachable.catch" :
                         "unreachable.catch.1";
@@ -1171,6 +1171,12 @@ public class Flow extends TreeScanner {
             }
         }
     }
+    //where
+        private boolean isExceptionOrThrowable(Type exc) {
+            return exc.tsym == syms.throwableType.tsym ||
+                exc.tsym == syms.exceptionType.tsym;
+        }
+
 
     public void visitConditional(JCConditional tree) {
         scanCond(tree.cond);

test/tools/javac/6558548/T6558548.java

 /*
  * @test /nodynamiccopyright/
- * @bug     6558548
+ * @bug     6558548 7039937
  * @summary The compiler needs to be aligned with clarified specification of throws
  * @compile/fail/ref=T6558548_latest.out -XDrawDiagnostics T6558548.java
- * @compile/fail/ref=T6558548_6.out -source 6 -XDrawDiagnostics T6558548.java
+ * @compile/fail/ref=T6558548_6.out -source 6 -Xlint:-options -XDrawDiagnostics T6558548.java
  */
 
 class T6558548 {
@@ -12,7 +12,7 @@ class T6558548 {
     void checked() throws InterruptedException {}
     void runtime() throws IllegalArgumentException {}
 
-    void m1() {
+    void m1a() {
         try {
             throw new java.io.FileNotFoundException();
         }
@@ -20,7 +20,7 @@ class T6558548 {
         catch(java.io.IOException exc) { } // 6: ok; latest: unreachable
     }
 
-    void m1a() {
+    void m1b() {
         try {
             throw new java.io.IOException();
         }
@@ -28,11 +28,20 @@ class T6558548 {
         catch(java.io.IOException exc) { } //ok
     }
 
-    void m2() {
+    void m1c() {
         try {
-            nothing();
+            throw new java.io.FileNotFoundException();
         }
-        catch(Exception exc) { } // ok
+        catch(java.io.FileNotFoundException exc) { }
+        catch(Exception ex) { } //ok (Exception/Throwable always allowed)
+    }
+
+    void m1d() {
+        try {
+            throw new java.io.FileNotFoundException();
+        }
+        catch(java.io.FileNotFoundException exc) { }
+        catch(Throwable ex) { } //ok (Exception/Throwable always allowed)
     }
 
     void m3() {
@@ -131,7 +140,7 @@ class T6558548 {
             runtime();
         }
         catch(RuntimeException exc) { }
-        catch(Exception exc) { } //6: ok; latest: unreachable
+        catch(Exception exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m17() {
@@ -139,7 +148,7 @@ class T6558548 {
             nothing();
         }
         catch(RuntimeException exc) { }
-        catch(Exception exc) { } //6: ok; latest: unreachable
+        catch(Exception exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m18() {
@@ -148,7 +157,7 @@ class T6558548 {
         }
         catch(RuntimeException exc) { }
         catch(InterruptedException exc) { }
-        catch(Exception exc) { } //6: ok; latest: unreachable
+        catch(Exception exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m19() {
@@ -157,7 +166,7 @@ class T6558548 {
         }
         catch(RuntimeException exc) { }
         catch(InterruptedException exc) { } //never thrown in try
-        catch(Exception exc) { } //6: ok; latest: unreachable
+        catch(Exception exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m20() {
@@ -166,7 +175,7 @@ class T6558548 {
         }
         catch(RuntimeException exc) { }
         catch(InterruptedException exc) { } //never thrown in try
-        catch(Exception exc) { } //6: ok; latest: unreachable
+        catch(Exception exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m21() {
@@ -182,7 +191,7 @@ class T6558548 {
             runtime();
         }
         catch(RuntimeException exc) { }
-        catch(Exception exc) { } // 6: ok; latest: unreachable
+        catch(Exception exc) { } // 6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m23() {
@@ -190,7 +199,7 @@ class T6558548 {
             nothing();
         }
         catch(RuntimeException exc) { }
-        catch(Exception exc) { } // 6: ok; latest: unreachable
+        catch(Exception exc) { } // 6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m24() {
@@ -208,7 +217,7 @@ class T6558548 {
         }
         catch(RuntimeException exc) { }
         catch(Error exc) { }
-        catch(Throwable exc) { } //6: ok; latest: unreachable
+        catch(Throwable exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m26() {
@@ -217,7 +226,7 @@ class T6558548 {
         }
         catch(RuntimeException exc) { }
         catch(Error exc) { }
-        catch(Throwable exc) { } //6: ok; latest: unreachable
+        catch(Throwable exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m27() {
@@ -227,7 +236,7 @@ class T6558548 {
         catch(RuntimeException exc) { }
         catch(Error exc) { }
         catch(InterruptedException exc) { }
-        catch(Throwable exc) { } //6: ok; latest: unreachable
+        catch(Throwable exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m28() {
@@ -237,7 +246,7 @@ class T6558548 {
         catch(RuntimeException exc) { }
         catch(Error exc) { }
         catch(InterruptedException exc) { } //never thrown in try
-        catch(Throwable exc) { } //6: ok; latest: unreachable
+        catch(Throwable exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m29() {
@@ -247,7 +256,7 @@ class T6558548 {
         catch(RuntimeException exc) { }
         catch(Error exc) { }
         catch(InterruptedException exc) { } //never thrown in try
-        catch(Throwable exc) { } //6: ok; latest: unreachable
+        catch(Throwable exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m30() {
@@ -265,7 +274,7 @@ class T6558548 {
         }
         catch(RuntimeException exc) { }
         catch(Error exc) { }
-        catch(Throwable exc) { } //6: ok; latest: unreachable
+        catch(Throwable exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m32() {
@@ -274,7 +283,7 @@ class T6558548 {
         }
         catch(RuntimeException exc) { }
         catch(Error exc) { }
-        catch(Throwable exc) { } //6: ok; latest: unreachable
+        catch(Throwable exc) { } //6: ok; latest: ok (Exception/Throwable always allowed)
     }
 
     void m33() {

test/tools/javac/6558548/T6558548_6.out

-- compiler.warn.source.no.bootclasspath: 1.6
-T6558548.java:159:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
 T6558548.java:168:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
-T6558548.java:239:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
-T6558548.java:249:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
-T6558548.java:291:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
-T6558548.java:298:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:177:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:248:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:258:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:300:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:307:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
 6 errors
-1 warning

test/tools/javac/6558548/T6558548_latest.out

 T6558548.java:20:9: compiler.warn.unreachable.catch: java.io.FileNotFoundException
-T6558548.java:134:9: compiler.warn.unreachable.catch: java.lang.RuntimeException
-T6558548.java:142:9: compiler.warn.unreachable.catch: java.lang.RuntimeException
-T6558548.java:151:9: compiler.warn.unreachable.catch.1: java.lang.InterruptedException,java.lang.RuntimeException
-T6558548.java:159:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
-T6558548.java:160:9: compiler.warn.unreachable.catch: java.lang.RuntimeException
 T6558548.java:168:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
-T6558548.java:169:9: compiler.warn.unreachable.catch: java.lang.RuntimeException
-T6558548.java:185:9: compiler.warn.unreachable.catch: java.lang.RuntimeException
-T6558548.java:193:9: compiler.warn.unreachable.catch: java.lang.RuntimeException
-T6558548.java:211:9: compiler.warn.unreachable.catch.1: java.lang.RuntimeException,java.lang.Error
-T6558548.java:220:9: compiler.warn.unreachable.catch.1: java.lang.RuntimeException,java.lang.Error
-T6558548.java:230:9: compiler.warn.unreachable.catch.1: java.lang.InterruptedException,java.lang.RuntimeException,java.lang.Error
-T6558548.java:239:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
-T6558548.java:240:9: compiler.warn.unreachable.catch.1: java.lang.RuntimeException,java.lang.Error
-T6558548.java:249:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
-T6558548.java:250:9: compiler.warn.unreachable.catch.1: java.lang.RuntimeException,java.lang.Error
-T6558548.java:268:9: compiler.warn.unreachable.catch.1: java.lang.RuntimeException,java.lang.Error
-T6558548.java:277:9: compiler.warn.unreachable.catch.1: java.lang.RuntimeException,java.lang.Error
-T6558548.java:291:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
-T6558548.java:298:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:177:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:248:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:258:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:300:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
+T6558548.java:307:9: compiler.err.except.never.thrown.in.try: java.lang.InterruptedException
 6 errors
-15 warnings
+1 warning

test/tools/javac/diags/examples/UnreachableCatch1.java

@@ -23,14 +23,21 @@
 
 // key: compiler.warn.unreachable.catch.1
 
+import java.io.*;
+
 class UnreachableCatch1 {
 
     void test() {
         try {
-            throw new IllegalArgumentException();
+            if (true) {
+                throw new FileNotFoundException();
+            }
+            else {
+                throw new EOFException();
+            }
         }
-        catch(Error err) { }
-        catch(RuntimeException rex) { }
-        catch(Throwable t) { } //unreachable
+        catch(FileNotFoundException fnf) { }
+        catch(EOFException eof) { }
+        catch(IOException ex) { } //unreachable
     }
 }