C++23 attributte assume

- [attribute [[assume]]](https://en.cppreference.com/w/cpp/language/attributes/assume) [P1774R8](https://wg21.link/P1774R8)
- linked SonarOpenCommunity#2536

cxx-squid/src/test/java/org/sonar/cxx/parser/AttributeTest.java

@@ -46,7 +46,9 @@ void classSpecifier_reallife() {
       .matches("[[fallthrough]]")
       .matches("[[nodiscard]]")
       .matches("[[maybe_unused]]")
-      .matches("[[attr1]] [[attr2]] [[attr3]]");
+      .matches("[[attr1]] [[attr2]] [[attr3]]")
+      //C++23
+      .matches("[[assume((x - 1) * 3 == 12)]]");
   }
 
 }

cxx-squid/src/test/resources/parser/own/C++23/attributte-assume.cc

@@ -0,0 +1,35 @@
+void f(int& x, int y)
+{
+    void g(int);
+    void h();
+
+    [[assume(x > 0)]]; // Compiler may assume x is positive
+
+    g(x / 2); // More efficient code possibly generated
+
+    x = 3;
+    int z = x;
+
+    [[assume((h(), x == z))]]; // Compiler may assume x would have the same value after
+                               // calling h
+                               // The assumption does not cause a call to h
+
+    h();
+    g(x); // Compiler may replace this with g(3);
+
+    h();
+    g(x); // Compiler may NOT replace this with g(3);
+          // An assumption applies only at the point where it appears
+
+    z = std::abs(y);
+
+    [[assume((g(z), true))]]; // Compiler may assume g(z) will return
+
+    g(z); // Due to above and below assumptions, compiler may replace this with g(10);
+
+    [[assume(y == -10)]]; // Undefined behavior if y != -10 at this point
+
+    [[assume((x - 1) * 3 == 12)]];
+
+    g(x); // Compiler may replace this with g(5);
+}