Preserve duplicate warnings for matching string prefix literals

Author: tzi4

lib/astutils.cpp

@@ -1608,10 +1608,20 @@ bool isSameExpression(bool macro, const Token *tok1, const Token *tok2, const Se
     if (tok1 == nullptr || tok2 == nullptr)
         return false;
     // An unknown string-prefix macro leaves the literal outside the AST.
-    // Comparing only the macro name would ignore the rest of the expression.
-    if ((!tok1->isKeyword() && Token::Match(tok1, "%name% %str%")) ||
-        (!tok2->isKeyword() && Token::Match(tok2, "%name% %str%")))
-        return false;
+    // Compare the literal text as well so identical literals still compare equal.
+    const bool stringPrefix1 = !tok1->isKeyword() && Token::Match(tok1, "%name% %str%");
+    const bool stringPrefix2 = !tok2->isKeyword() && Token::Match(tok2, "%name% %str%");
+    if (stringPrefix1 || stringPrefix2) {
+        if (!stringPrefix1 || !stringPrefix2)
+            return false;
+        for (const Token* str1 = tok1->next(), *str2 = tok2->next();
+             Token::Match(str1, "%str%") || Token::Match(str2, "%str%");
+             str1 = str1->next(), str2 = str2->next()) {
+            if (!Token::Match(str1, "%str%") || !Token::Match(str2, "%str%") ||
+                str1->str() != str2->str() || !compareTokenFlags(str1, str2, macro))
+                return false;
+        }
+    }
     // tokens needs to be from the same TokenList so no need check standard on both of them
     if (tok1->isCpp()) {
         if (tok1->str() == "." && tok1->astOperand1() && tok1->astOperand1()->str() == "this")

test/testastutils.cpp

@@ -202,6 +202,11 @@ class TestAstUtils : public TestFixture {
         ASSERT_EQUALS(false, isSameExpression("x == PREFIX \"/a\" || x == PREFIX \"/b\";\n", "==", "==", cpp));
         ASSERT_EQUALS(false, isSameExpression("x == PREFIX \"/a\" || x == PREFIX;\n", "==", "==", cpp));
         ASSERT_EQUALS(false, isSameExpression("x == PREFIX || x == PREFIX \"/a\";\n", "==", "==", cpp));
+        ASSERT_EQUALS(true,  isSameExpression("x == PREFIX \"/a\" || x == PREFIX \"/a\";\n", "==", "==", cpp));
+        ASSERT_EQUALS(true,  isSameExpression("x == PREFIX \"/a\" \"/b\" || x == PREFIX \"/a\" \"/b\";\n", "==", "==", cpp));
+        ASSERT_EQUALS(false, isSameExpression("x == PREFIX \"/a\" \"/b\" || x == PREFIX \"/a\" \"/c\";\n", "==", "==", cpp));
+        ASSERT_EQUALS(false, isSameExpression("x == FIRST \"/a\" || x == SECOND \"/a\";\n", "==", "==", cpp));
+        ASSERT_EQUALS(false, isSameExpression("x == PREFIX L\"/a\" || x == PREFIX \"/a\";\n", "==", "==", cpp));
 
         // the remaining test cases are not valid C code
         if (!cpp)

test/testother.cpp

@@ -12170,6 +12170,11 @@ class TestOther : public TestFixture {
               "        : (name.startswith(SRCDIR \"/com/\") || name.startswith(SRCDIR \"/uno/\"));\n"
               "}\n", dinit(CheckOptions, $.inconclusive = false));
         ASSERT_EQUALS("", errout_str());
+
+        check("bool f(StringRef name) {\n"
+              "    return name == SRCDIR \"/a\" || name == SRCDIR \"/a\";\n"
+              "}\n", dinit(CheckOptions, $.inconclusive = false));
+        ASSERT_EQUALS("[test.cpp:2:32]: (style) Same expression on both sides of '||'. [duplicateExpression]\n", errout_str());
     }
 
     void raceAfterInterlockedDecrement() {