fix: resolve char literal incorrect print as string (#856)

jadx-core/src/main/java/jadx/core/Consts.java

@@ -4,6 +4,7 @@ public class Consts {
 	public static final boolean DEBUG = false;
 	public static final boolean DEBUG_USAGE = false;
 	public static final boolean DEBUG_TYPE_INFERENCE = false;
+	public static final boolean DEBUG_OVERLOADED_CASTS = false;
 
 	public static final String CLASS_OBJECT = "java.lang.Object";
 	public static final String CLASS_STRING = "java.lang.String";

jadx-core/src/main/java/jadx/core/codegen/TypeGen.java

@@ -3,7 +3,6 @@ package jadx.core.codegen;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import jadx.core.deobf.NameMapper;
 import jadx.core.dex.attributes.AFlag;
 import jadx.core.dex.instructions.args.ArgType;
 import jadx.core.dex.instructions.args.LiteralArg;
@@ -71,11 +70,7 @@ public class TypeGen {
 			case BOOLEAN:
 				return lit == 0 ? "false" : "true";
 			case CHAR:
-				char ch = (char) lit;
-				if (!NameMapper.isPrintableChar(ch)) {
-					return Integer.toString(ch);
-				}
-				return stringUtils.unescapeChar(ch);
+				return stringUtils.unescapeChar((char) lit, cast);
 			case BYTE:
 				return formatByte(lit, cast);
 			case SHORT:

jadx-core/src/main/java/jadx/core/dex/visitors/MethodInvokeVisitor.java

@@ -278,13 +278,14 @@ public class MethodInvokeVisitor extends AbstractVisitor {
 		if (argsCount == 1) {
 			return mthDetails.getArgTypes();
 		}
-		// TODO: try to minimize casts count
-		parentMth.addComment("JADX DEBUG: Failed to find minimal casts for resolve overloaded methods, cast all args instead"
-				+ NL + " method: " + mthDetails
-				+ NL + " arg types: " + compilerVarTypes
-				+ NL + " candidates:"
-				+ NL + "  " + Utils.listToString(overloadedMethods, NL + "  "));
-
+		if (Consts.DEBUG_OVERLOADED_CASTS) {
+			// TODO: try to minimize casts count
+			parentMth.addComment("JADX DEBUG: Failed to find minimal casts for resolve overloaded methods, cast all args instead"
+					+ NL + " method: " + mthDetails
+					+ NL + " arg types: " + compilerVarTypes
+					+ NL + " candidates:"
+					+ NL + "  " + Utils.listToString(overloadedMethods, NL + "  "));
+		}
 		// not resolved -> cast all args
 		return mthDetails.getArgTypes();
 	}

jadx-core/src/main/java/jadx/core/utils/StringUtils.java

@@ -1,6 +1,9 @@
 package jadx.core.utils;
 
+import org.jetbrains.annotations.Nullable;
+
 import jadx.api.JadxArgs;
+import jadx.core.deobf.NameMapper;
 
 public class StringUtils {
 	private static final StringUtils DEFAULT_INSTANCE = new StringUtils(new JadxArgs());
@@ -24,57 +27,74 @@ public class StringUtils {
 		res.append('"');
 		for (int i = 0; i < len; i++) {
 			int c = str.charAt(i) & 0xFFFF;
-			processChar(c, res);
+			processCharInsideString(c, res);
 		}
 		res.append('"');
 		return res.toString();
 	}
 
-	public String unescapeChar(char ch) {
-		if (ch == '\'') {
-			return "'\\\''";
+	private void processCharInsideString(int c, StringBuilder res) {
+		String str = getSpecialStringForChar(c);
+		if (str != null) {
+			res.append(str);
+			return;
+		}
+		if (c < 32 || c >= 127 && escapeUnicode) {
+			res.append("\\u").append(String.format("%04x", c));
+		} else {
+			res.append((char) c);
 		}
-		StringBuilder res = new StringBuilder();
-		res.append('\'');
-		processChar(ch, res);
-		res.append('\'');
-		return res.toString();
 	}
 
-	private void processChar(int c, StringBuilder res) {
+	/**
+	 * Represent single char best way possible
+	 */
+	public String unescapeChar(int c, boolean explicitCast) {
+		if (c == '\'') {
+			return "'\\''";
+		}
+		String str = getSpecialStringForChar(c);
+		if (str != null) {
+			return '\'' + str + '\'';
+		}
+		if (c >= 127 && escapeUnicode) {
+			return String.format("'\\u%04x'", c);
+		}
+		if (NameMapper.isPrintableChar(c)) {
+			return "'" + (char) c + '\'';
+		}
+		if (explicitCast) {
+			return "(char) " + c;
+		}
+		return String.valueOf(c);
+	}
+
+	public String unescapeChar(char ch) {
+		return unescapeChar(ch, false);
+	}
+
+	@Nullable
+	private String getSpecialStringForChar(int c) {
 		switch (c) {
 			case '\n':
-				res.append("\\n");
-				break;
+				return "\\n";
 			case '\r':
-				res.append("\\r");
-				break;
+				return "\\r";
 			case '\t':
-				res.append("\\t");
-				break;
+				return "\\t";
 			case '\b':
-				res.append("\\b");
-				break;
+				return "\\b";
 			case '\f':
-				res.append("\\f");
-				break;
+				return "\\f";
 			case '\'':
-				res.append('\'');
-				break;
+				return "'";
 			case '"':
-				res.append("\\\"");
-				break;
+				return "\\\"";
 			case '\\':
-				res.append("\\\\");
-				break;
+				return "\\\\";
 
 			default:
-				if (c < 32 || c >= 127 && escapeUnicode) {
-					res.append("\\u").append(String.format("%04x", c));
-				} else {
-					res.append((char) c);
-				}
-				break;
+				return null;
 		}
 	}
 

jadx-core/src/test/java/jadx/tests/functional/StringUtilsTest.java

@@ -43,8 +43,9 @@ class StringUtilsTest {
 		checkCharUnescape('a', "a");
 		checkCharUnescape(' ', " ");
 		checkCharUnescape('\n', "\\n");
-		checkCharUnescape('\'', "\\\'");
-		checkCharUnescape('\0', "\\u0000");
+		checkCharUnescape('\'', "\\'");
+
+		assertThat(stringUtils.unescapeChar('\0'), is("0"));
 	}
 
 	private void checkCharUnescape(char input, String result) {

jadx-core/src/test/java/jadx/tests/integration/invoke/TestCastInOverloadedInvoke4.java

@@ -0,0 +1,24 @@
+package jadx.tests.integration.invoke;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.tests.api.IntegrationTest;
+
+import static jadx.tests.api.utils.assertj.JadxAssertions.assertThat;
+
+public class TestCastInOverloadedInvoke4 extends IntegrationTest {
+
+	public static class TestCls {
+		public String test(String str) {
+			return str.replace('\n', ' ');
+		}
+	}
+
+	@Test
+	public void test() {
+		noDebugInfo();
+		assertThat(getClassNode(TestCls.class))
+				.code()
+				.containsOne("return str.replace('\\n', ' ');");
+	}
+}