[llvm-bugs] [Bug 28050] New: Deprecated (legacy) string literal conversion to 'char *' causes strange overloading resolution

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https://llvm.org/bugs/show_bug.cgi?id=28050

            Bug ID: 28050
           Summary: Deprecated (legacy) string literal conversion to 'char
                    *' causes strange overloading resolution
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: C++11
          Assignee: unassignedclangbugs at nondot.org
          Reporter: mO_Okar at mail.ru
                CC: dgregor at apple.com, llvm-bugs at lists.llvm.org
    Classification: Unclassified

The conversion from string literal to 'char *' makes the compiler to choose
initialization through the move constructor. See the following example:

$ cat test.cpp
class A {
public:
  A(char *s) {}
  A(A &&) = delete;
};

void test() { A a("OK"); }
$ clang -cc1 -std=c++11 -fsyntax-only test.cpp
test.cpp:7:17: error: call to deleted constructor of 'A'
void test() { A a("OK"); }
                ^ ~~~~
test.cpp:4:3: note: 'A' has been explicitly marked deleted here
  A(A &&) = delete;
  ^
1 error generated.

If we remove the '= delete' part, we'll get the following AST for function
'test':

`-FunctionDecl {{.*}} test 'void (void)'
  `-CompoundStmt {{.*}}
    `-DeclStmt {{.*}}
      `-VarDecl {{.*}} a 'class A' callinit
        `-CXXConstructExpr {{.*}} 'class A' 'void (class A &&)' elidable
          `-MaterializeTemporaryExpr {{.*}} 'class A' xvalue
            `-CXXConstructExpr {{.*}} 'class A' 'void (char *)'
              `-ImplicitCastExpr {{.*}} 'char *' <NoOp>
                `-ImplicitCastExpr {{.*}} 'const char *' <ArrayToPointerDecay>
                  `-StringLiteral {{.*}} 'const char [3]' lvalue "OK"

However, other standard conversions (like numeric promotion and even
qualification adjustment) are not affected.


Alexander Makarov,
Intel Software Engineer

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