FailSummary.txt

In Non-Debug mode:
Failure 1: 
    Cannot add Position to Velocity (Line 338)
    Error messages such as:
        "error: invalid operands to binary expression"
        "error: no match for ‘operator+’"

Failure 2:
    Multiple assertion fails - trying to initialise with wrong types (Lines 380, 382, 384)
    Error messages such as:
        "error: static_assert failed due to requirement 'std::is_same_v<double, int>' "Initialiser list type must match storage data-type or units" "
        "error: static assertion failed: Initialiser list type must match storage data-type or units"

Failure 3:
    Conversion error (Line 386) - trying to set equal to a plain double
        "error: no viable conversion from 'double' to 'Length'"
        "error: conversion from ‘double’ to non-scalar type ‘Length’"

Failure 4:
    a. Trying to use plain get on a value with units (Line 397)
    b. Trying to use power at runtime when value has units (Line 443)
        "error: static_assert failed due to requirement 'hasNoUnits()'"
        "error: static assertion failed
            static_assert(hasNoUnits());"

Failure 5:
    Using a Narrowing conversion (Line 512)
    NOTE: this is only a warning in GCC
        "error: non-constant-expression cannot be narrowed from type 'double' to 'float' in initializer list" [Clang]
        "warning: narrowing conversion of ‘tmp2’ from ‘double’ to ‘float’" [GCC]

Failure 6:
    Issues with references and misuse of constness, r-values etc
    a. Trying to get a non-const reference to a temporary, which is a const ref
        error: static_assert failed due to requirement '!STScalarRef<double, true>::is_const_v' "Error: Trying to remove const from a reference!"
        error: static assertion failed: Error: Trying to remove const from a reference!
    b. Ditto, but for a normal type, so compiler detects this
        error: non-const lvalue reference to type 'double' cannot bind to a temporary of type 'double'
        cannot bind non-const lvalue reference of type 'double&' to an rvalue of type 'double'
    c. Trying to write to a const-ref type
         error: static_assert failed due to requirement '!true' "Cannot assign to const reference"
         error: static assertion failed: Cannot assign to const reference
    d. Using a (const)-ref-to-rvalue after the line it is created
        shows as an assertion error on the value, depending on optimisation
        NOTE: we are allowed to use the _reference_ object, but NOT the value it references.