[Bug c++/85914] New: -Wreturn-type false positive with tautological ternery

[Anderson.Ku at synopsys dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85914

            Bug ID: 85914
           Summary: -Wreturn-type false positive with tautological ternery
           Product: gcc
           Version: 7.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Anderson.Ku at synopsys dot com
  Target Milestone: ---

$uname -a
Linux anku-Z440 4.4.0-109-generic #132-Ubuntu SMP Tue Jan 9 19:52:39 UTC 2018
x86_64 x86_64 x86_64 GNU/Linux

$g++ --version
g++ (GCC) 7.1.0

$g++ /u/anku/test.cpp -c -Wreturn-type
/u/anku/test.cpp: In function 'int processDMInitActivity(int)':
/u/anku/test.cpp:16:1: warning: control reaches end of non-void function
[-Wreturn-type]
 }
 ^

Adding -O1, -O2, or O3 removes the warning

isolated code:

__attribute__((noreturn)) void throw_assert();

struct MyClassWithVirtualDtor{
    virtual ~MyClassWithVirtualDtor();
};

int processDMInitActivity(int x) {
    MyClassWithVirtualDtor mcf;
    if(x) {
        return -1;
    }
    false ? void(0) : throw_assert();

    // This also warns
    // false ? void(0) : throw 303;
}