[llvm-bugs] [Bug 25642] New: -Wpessimizing-move fixit introduces -Wvexing-parse

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=25642

            Bug ID: 25642
           Summary: -Wpessimizing-move fixit introduces -Wvexing-parse
           Product: clang
           Version: 3.7
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Frontend
          Assignee: unassignedclangbugs at nondot.org
          Reporter: sugak at fb.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

For the following code -Wpessimizing-move, suggests a fixit to remove call to
std::move:
```
#include <utility>
struct C { };
void f() {
  C c(std::move(C()));
}
1.cpp:4:7: warning: moving a temporary object prevents copy elision
[-Wpessimizing-move]
  C c(std::move(C()));
      ^
1.cpp:4:7: note: remove std::move call here
  C c(std::move(C()));
      ^~~~~~~~~~   ~
1 warning generated.
```
When the fixit is applied, that variable declaration becomes function
declaration, it changes semantics, and introduced -Wvexing-parse violation:
```
1.cpp:4:6: warning: parentheses were disambiguated as a function declaration
[-Wvexing-parse]
  C c(C());
     ^~~~~
1.cpp:4:7: note: add a pair of parentheses to declare a variable
  C c(C());
      ^
      (  )
1 warning generated.
```

This is not a big deal. But since clang-tidy automatically apply such fixits it
would be nice to avoid semantics changes.

clang version 3.8.0 (trunk 251726)
Target: x86_64-unknown-linux-gnu
Thread model: posix

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