Tracking ASM 5.0.4 development: Fix for ASM issue 317545

Issue: SPR-12470

spring-core/src/main/java/org/springframework/asm/ClassReader.java

@@ -1173,7 +1173,14 @@ public class ClassReader {
                         if (labels[label] == null) {
                             readLabel(label, labels).status |= Label.DEBUG;
                         }
-                        labels[label].line = readUnsignedShort(v + 12);
+                        Label l = labels[label];
+                        while (l.line > 0) {
+                            if (l.next == null) {
+                                l.next = new Label();
+                            }
+                            l = l.next;
+                        }
+                        l.line = readUnsignedShort(v + 12);
                         v += 4;
                     }
                 }
@@ -1288,9 +1295,15 @@ public class ClassReader {
             // visits the label and line number for this offset, if any
             Label l = labels[offset];
             if (l != null) {
+                Label next = l.next;
+                l.next = null;
                 mv.visitLabel(l);
                 if ((context.flags & SKIP_DEBUG) == 0 && l.line > 0) {
                     mv.visitLineNumber(l.line, l);
+                    while (next != null) {
+                        mv.visitLineNumber(next.line, l);
+                        next = next.next;
+                    }
                 }
             }
 

spring-core/src/main/java/org/springframework/asm/Label.java

@@ -131,7 +131,11 @@ public class Label {
     int status;
 
     /**
-     * The line number corresponding to this label, if known.
+     * The line number corresponding to this label, if known. If there are
+     * several lines, each line is stored in a separate label, all linked via
+     * their next field (these links are created in ClassReader and removed just
+     * before visitLabel is called, so that this does not impact the rest of the
+     * code).
      */
     int line;
 
@@ -154,7 +158,7 @@ public class Label {
      * indicates if this reference uses 2 or 4 bytes, and its absolute value
      * gives the position of the bytecode instruction. This array is also used
      * as a bitset to store the subroutines to which a basic block belongs. This
-     * information is needed in {@linked MethodWriter#visitMaxs}, after all
+     * information is needed in {@link MethodWriter#visitMaxs}, after all
      * forward references have been resolved. Hence the same array can be used
      * for both purposes without problems.
      */
@@ -239,7 +243,8 @@ public class Label {
      * The next basic block in the basic block stack. This stack is used in the
      * main loop of the fix point algorithm used in the second step of the
      * control flow analysis algorithms. It is also used in
-     * {@link #visitSubroutine} to avoid using a recursive method.
+     * {@link #visitSubroutine} to avoid using a recursive method, and in
+     * ClassReader to temporarily store multiple source lines for a label.
      *
      * @see MethodWriter#visitMaxs
      */