Merge branch 'master' into 7.0.x

pmd-go/src/main/antlr4/net/sourceforge/pmd/lang/go/antlr4/Golang.g4

@@ -917,10 +917,10 @@ RUNE_LIT
 
 //unicode_value    = unicode_char | little_u_value | big_u_value | escaped_char .
 fragment UNICODE_VALUE
-    : UNICODE_CHAR
-    | LITTLE_U_VALUE
+    : LITTLE_U_VALUE
     | BIG_U_VALUE
     | ESCAPED_CHAR
+    | UNICODE_CHAR
     ;
 
 //byte_value       = octal_byte_value | hex_byte_value .

pmd-go/src/test/java/net/sourceforge/pmd/cpd/EdgeCasesTokenizerTest.java

@@ -0,0 +1,29 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.cpd;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+
+import org.apache.commons.io.IOUtils;
+import org.junit.Test;
+
+public class EdgeCasesTokenizerTest {
+
+    private String getSampleCode(final String filename) throws IOException {
+        return IOUtils.toString(GoTokenizer.class.getResourceAsStream(filename), StandardCharsets.UTF_8);
+    }
+
+    @Test
+    public void testEscapedBackSlash() throws IOException {
+        // See https://github.com/pmd/pmd/issues/1751
+        final String filename = "issue1751.go";
+        final GoTokenizer tokenizer = new GoTokenizer();
+        final SourceCode sourceCode = new SourceCode(new SourceCode.StringCodeLoader(getSampleCode(filename), filename));
+        
+        final Tokens tokens = new Tokens();
+        tokenizer.tokenize(sourceCode, tokens); // it should simply not fail
+    }
+}

pmd-go/src/test/resources/net/sourceforge/pmd/cpd/issue1751.go

@@ -0,0 +1,6 @@
+func test(in *Value, param *Value) (*Value, *Error) {
+	output := strings.Replace(in.String(), "\\", "\\\\", -1)
+	output = strings.Replace(output, "\"", "\\\"", -1)
+	output = strings.Replace(output, "'", "\\'", -1)
+	return AsValue(output), nil
+}