ForExtendBlock returns the source code location of the "extend" block that contains the given extension.

ForExtensionsStatement returns the source code location of the "extensions" statement that defines the extension range at the given index.

ForReservedNamesStatement returns the source code location of the "reserved" statement that contains the reserved name at the given index.

ForReservedRangesStatement returns the source code location of the "reserved" statement that contains the reserved range at the given index.

IsSubpathOf returns true if the given candidate is a subpath of the given path.

IsSubspanOf returns true if the given candidate is a subspan (i.e.

IsZero returns true if loc is a zero-value SourceLocation.

PathFor computes the source path for the given descriptor.