Why doesn't the /Zc:twoPhase- compiler switch which follows the /permissive- switch cause the compilation errors to disappear in MSVC 19.13, just like they disappear when the /permissive-` switch is completely removed, with the following problem code ?
#include <stdio.h>
template <unsigned int BYTES>
class CBase
{
public:
char Arr[BYTES];
int Fn1(void) {
return Arr[1] ^ Arr[sizeof(Arr)-1];
}
int Fn2(void) {
return Arr[2] ^ Arr[sizeof(Arr)-2];
}
};
template <unsigned int BYTES>
class CDerived : public CBase<BYTES>
{
public:
int FnSum(void) {
return Fn1() + Fn2() + Arr[0]; // ERRORs: identifiers "Fn1" and "Fn2" and "Arr" are NOT found !
}
};
int main(void)
{
CDerived<32> ddd;
printf("%d\n", ddd.Fn1()); //No error here
printf("%d\n", ddd.Fn2()); //No error here
printf("%d\n", ddd.FnSum());
return (int)ddd.Arr[0]; //No error here
}
The above code compiles in MSVC v19.10 when the /permissive- switch is completely removed.
See: https://godbolt.org/g/Yxw89Y
NOTE: I cannot include a link to an example on http://godbolt.org with the /permissive- /Zc:twoPhase- switches together, because the latest Godbolt MSVC compiler (v19.10) is outdated and does not support the /Zc:twoPhase- compiler switch.
According to this article and this article, the compilation error in MSVC comes from the Two-Phase Name Lookup being enabled by the conformance to the C++ standard mode ( enabled by the /permissive- option).
Also, according to the former article: "The /permissive- option implicitly sets the conforming two-phase lookup compiler behavior, but it can be overridden by using /Zc:twoPhase- switch".
However adding the two compiler switches /permissive- /Zc:twoPhase- (in that order) does not override it and does not make the compilation errors disappear in MSVC v19.13.
For the Context of this problem, see this entry.
