fix: preserve arg type on PHI insn inline (#718)

jadx-core/src/main/java/jadx/core/dex/visitors/blocksmaker/BlockProcessor.java

@@ -677,7 +677,7 @@ public class BlockProcessor extends AbstractVisitor {
 		InsnNode insn = new InsnNode(returnInsn.getType(), returnInsn.getArgsCount());
 		if (returnInsn.getArgsCount() == 1) {
 			RegisterArg arg = (RegisterArg) returnInsn.getArg(0);
-			insn.addArg(InsnArg.reg(arg.getRegNum(), arg.getInitType()));
+			insn.addArg(arg.duplicate());
 		}
 		insn.copyAttributesFrom(returnInsn);
 		insn.setOffset(returnInsn.getOffset());

jadx-core/src/main/java/jadx/core/dex/visitors/ssa/SSATransform.java

@@ -12,7 +12,6 @@ import jadx.core.dex.attributes.AType;
 import jadx.core.dex.attributes.nodes.PhiListAttr;
 import jadx.core.dex.instructions.InsnType;
 import jadx.core.dex.instructions.PhiInsn;
-import jadx.core.dex.instructions.args.ArgType;
 import jadx.core.dex.instructions.args.InsnArg;
 import jadx.core.dex.instructions.args.RegisterArg;
 import jadx.core.dex.instructions.args.SSAVar;
@@ -383,25 +382,18 @@ public class SSATransform extends AbstractVisitor {
 		List<RegisterArg> useList = resVar.getUseList();
 		for (RegisterArg useArg : new ArrayList<>(useList)) {
 			InsnNode useInsn = useArg.getParentInsn();
-			if (useInsn == null || useInsn == phi) {
+			if (useInsn == null || useInsn == phi || useArg.getRegNum() != arg.getRegNum()) {
 				return false;
 			}
+			// replace SSAVar in 'useArg' to SSAVar from 'arg'
+			// no need to replace whole RegisterArg
 			useArg.getSVar().removeUse(useArg);
-			RegisterArg inlArg = arg.duplicate();
-			if (!useInsn.replaceArg(useArg, inlArg)) {
-				return false;
-			}
-			inlArg.getSVar().use(inlArg);
-			inlArg.setName(useArg.getName());
-			ArgType type = useArg.getImmutableType();
-			if (type != null) {
-				inlArg.setType(type);
-			}
+			arg.getSVar().use(useArg);
 		}
 		if (block.contains(AType.EXC_HANDLER)) {
 			// don't inline into exception handler
 			InsnNode assignInsn = arg.getAssignInsn();
-			if (assignInsn != null) {
+			if (assignInsn != null && !assignInsn.isConstInsn()) {
 				assignInsn.add(AFlag.DONT_INLINE);
 			}
 		}

jadx-core/src/test/java/jadx/tests/integration/inline/TestConstInline.java

+package jadx.tests.integration.inline;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.core.dex.nodes.ClassNode;
+import jadx.tests.api.IntegrationTest;
+
+import static jadx.tests.api.utils.JadxMatchers.containsOne;
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.not;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+public class TestConstInline extends IntegrationTest {
+
+	public static class TestCls {
+		public boolean test() {
+			try {
+				return f(0);
+			} catch (Exception e) {
+				return false;
+			}
+		}
+
+		public boolean f(int i) {
+			return true;
+		}
+	}
+
+	@Test
+	public void test() {
+		ClassNode cls = getClassNode(TestCls.class);
+		String code = cls.getCode().toString();
+
+		assertThat(code, containsOne("return f(0);"));
+		assertThat(code, containsOne("return false;"));
+		assertThat(code, not(containsString(" = ")));
+	}
+}