Mikhail Zarechenskiy
b7849da19e
This commit doesn't change behaviour of any inference algorithm, it introduces opportunity to switch constraint system that is used for overload resolution and fix problematic cases by changing one enum entry. Due to fundamental changes, there are cases where a new inference algorithm reports overload resolution ambiguity errors (#KT-31670, #KT-31758), which is correct from its point of view. However, this is a breaking change and to really make it, we should be very confident and have enough motivation for it, therefore, we don't change behavior now in order to collect more examples (if there are any). And if we find a lot of erroneous examples, we'll be able to change the behavior quite simply
Diagnostic tests format specification
Each diagnostic test consists of a single .kt file containing the code of one or several Kotlin or Java source files. Each diagnostic, be it a warning or an error, is marked in the following way:
<!DIAGNOSTIC_FACTORY_NAME!>element<!>
where DIAGNOSTIC_FACTORY_NAME is the name of the diagnostic which is usually one of the constants in one of Errors* classes.
To test not only the presence of the diagnostic but also the arguments which will be rendered to the user, provide string representations of all of them in the parentheses delimited with ; after the diagnostic name:
return <!TYPE_MISMATCH(String; Nothing)!>"OK"<!>
Note: if you're unsure what text should be added for the parameters, just leave the parentheses empty and the failed test will present the actual values in the assertion message.
Directives
Several directives can be added to the beginning of a test file with the following syntax:
// !DIRECTIVE
1. DIAGNOSTICS
This directive allows to exclude some irrelevant diagnostics (e.g. unused parameter) from a certain test, or to test only a specific set of diagnostics.
The syntax is
'([ + - ! ] DIAGNOSTIC_FACTORY_NAME | ERROR | WARNING | INFO ) +'
where
-
+means 'include'; -
-means 'exclude'; -
!means 'exclude everything but this'.Directives are applied in the order of appearance, i.e.
!FOO +BARmeans include onlyFOOandBAR.
Usage:
// !DIAGNOSTICS: -WARNING +CAST_NEVER_SUCCEEDS
// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
2. CHECK_TYPE
The directive adds the following declarations to the file:
fun <T> checkSubtype(t: T) = t
class Inv<T>
fun <E> Inv<E>._() {}
infix fun <T> T.checkType(f: Inv<T>.() -> Unit) {}
With that, an exact type of an expression can be checked in the following way:
fun test(expr: A) {
expr checkType { _<A>() }
}
CHECK_TYPE directive also disables UNDERSCORE_USAGE_WITHOUT_BACKTICKS diagnostics output.
Usage:
// !CHECK_TYPE
3. FILE
The directive lets you compose a test consisting of several files in one actual file.
Usage:
// FILE: A.java
/* Java code */
// FILE: B.kt
/* Kotlin code */
4. LANGUAGE
This directive lets you enable or disable certain language features. Language features are named as enum entries of the class LanguageFeature.
Each feature can be enabled with +, disabled with -, or enabled with warning with warn:.
Usage:
// !LANGUAGE: -TopLevelSealedInheritance
// !LANGUAGE: +TypeAliases -LocalDelegatedProperties
// !LANGUAGE: warn:Coroutines
5. API_VERSION
This directive emulates the behavior of the -api-version command line option, disallowing to use declarations annotated with @SinceKotlin(X) where X is greater than the specified API version.
Note that if this directive is present, the NEWER_VERSION_IN_SINCE_KOTLIN diagnostic is automatically disabled, unless the "!DIAGNOSTICS" directive is present.
Usage:
// !API_VERSION: 1.0
6. RENDER_DIAGNOSTICS_MESSAGES
This directive forces Diagnostic printer prints parametrized diagnostics with all parameters.
Usage:
// !RENDER_DIAGNOSTICS_MESSAGES