Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
support for checking values whose type is a type parameter
Type parameters
This commit implements support for checking exhaustiveness when the
value's type is a type parameter. The defined behavior is (copied from
package documentation):
A switch statement that switches on a value whose type is a type
parameter is checked for exhaustiveness iff each type element in the
type constraint is an enum type and shares the same underlying basic
kind. For example, the following switch statement will be checked,
assuming M, N, and O are enum types with the same underlying basic
kind. To satisfy exhaustiveness, all enum members for each of the
types M, N, and O must be listed in the switch statement's cases.
func bar[T M | I](v T) {
switch v {
}
}
type I interface{ N | J }
type J interface{ O }
Exhaustive supports go1.14 and later, but type parameters are only
supported from go1.18 or later. Symbols in e.g. package go/types related
to type parameters are not available in go version earlier than go1.18.
So source files, when necessary, are split into *_pre_go118.go and
*_go118.go portions.
The majority of the implementation is in common_go118.go.
Spurious diagnostic for type conversion (issue 42)
This commit also fixes spurious diagnostics that were produced when the
case clause expressions involved type conversions. See the relevant func
stripTypeConversions, and tests in testdata/general/x/typeconv.go.
Diagnostic format changes
The output diagnostics now always include the package name for the enum
type and the enum members. (Previously the package name was omitted if
the symbols were in the same package as the offending source code.) This
change was motivated by consistency: With type parameters, a value's
type in a switch statement tag can be composed of multiple enum types,
possibly from different packages. In such scenarios, consistently using
the package name for all of them makes for more comprehensible
diagnostics.
Many testdata lines are touched due to the diagnostic format change.
Internal changes
* Flag parsing: Parsing of the -check flag is now handled by a new
stringsFlag type that implements flag.Value.
* Shared code: Code that was shared (or should have been shared between)
switch.go and maps.go now lives in common.go.
* The enumMembers fact type has an additional NameToPos field.
* The checklist type is updated to account for the fact that enum types
can possibly be from multiple packages.
* The Makefile now includes a "cover" target (HTML test coverage report)
and an "all" target (runs build, vet, test).
* The new "member" type represents the concept of an enum member in
switch.go and map.go API, replacing the prev. largely string-based
API.
GitHub workflows
The workflow now runs tests for go versions < 1.16.
Fixes #31, #42- Loading branch information
