Are short circuit evaluation rules expected at compile time?

Question

Program A produces a compilation error (as expected) since isFinite is called with a non-integral type.

Program A

Answer 1

Short circuit is not supposed to compile true || (whatever_ill_formed). isFinite is instantiated as part of expression and during instantiation it should be compiled and during compilation it should static assert. After that the compiler may never evaluate isFinite(f) because of short circuit but static assert is not supposed to happen during it.

It is unclear why Visual Studio 2013 compiles Program B. Standard only allows bypassing syntax checking of templates when template is never instantiated. Even then the code is still ill formed only diagnostics are not required. Behind the defect is perhaps the same internal issue in Visual C++ that does not let Microsoft to implement constexpr.

Edit I add some language lawyer texts from standard per @zneak request

3.2/3

A function whose name appears as a potentially-evaluated expression is odr-used if it is the unique lookup result or the selected member of a set of overloaded functions (3.4, 13.3, 13.4), unless it is a pure virtual function and its name is not explicitly qualified. [Note: This covers calls to named functions (5.2.2), operator overloading (Clause 13), user-defined conversions (12.3.2), allocation function for placement new (5.3.4), as well as non-default initialization (8.5). A constructor selected to copy or move an object of class type is odr-used even if the call is actually elided by the implementation (12.8). —end note]

5.13/1

The || operator groups left-to-right. The operands are both contextually converted to bool (Clause 4). It returns true if either of its operands is true, and false otherwise. Unlike |, || guarantees left-to-right evaluation; moreover, the second operand is not evaluated if the first operand evaluates to true.

7.1/4

In a static_assert-declaration the constant-expression shall be a constant expression (5.19) that can be contextually converted to bool (Clause 4). If the value of the expression when so converted is true, the declaration has no effect. Otherwise, the program is ill-formed, and the resulting diagnostic message (1.4) shall include the text of the string-literal, except that characters not in the basic source character set (2.3) are not required to appear in the diagnostic message.

14.7.1/3

Unless a function template specialization has been explicitly instantiated or explicitly specialized, the function template specialization is implicitly instantiated when the specialization is referenced in a context that requires a function definition to exist.