[Chapel Merge] Expand and improve support for union

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Branch: refs/heads/main
Revision: c366cd519fc45f1c19e56ce2fc9ebee6444bde5e
Author: jabraham17
Link: Expand and improve support for union by jabraham17 · Pull Request #28601 · chapel-lang/chapel · GitHub
Log Message:
Expand and improve support for union (#28601)

Expands the support for the union type in Chapel

A key improvement is that users can use unions natively in a select
statement.

union U {
  var x: int;
  var y: real;
}
var u: U;
select u {
  when U.x {
    writeln("x is ", u.x);
  }
  when U.y {
    writeln("y is ", u.y);
  }
}

Or users can use functions to do dispatch

u.visit(proc(x: int) { writeln("x is ", u.x); },
          proc(y: real) { writeln("y is ", u.y); });

Resolves determining the active field of a union · Issue #11452 · chapel-lang/chapel · GitHub

In this PR

  • rewrites some compiler primitives to be 0 based instead of 1 based
  • affects reflection primitives for accessing fields of aggregates and
    union specific primitives
  • Adds an any union generic type to the compiler
  • Adds union.getActiveIndex to get the active element of the union
  • Adds UnionType.fieldName to get that fields index
  • Adds special pattern matching allowing users to write select u and
    when UnionType.field and have everything just work, see
    test/types/unions/selectPatterns.chpl.
  • Adds union.visit, allowing a user to pass FCF or functors to be
    called for the active union element
  • Adds union.getFieldIndex to get the index of a given field name (not
    user facing)
    • this is just a convenience wrapper over reflection functions
  • Adds union.this to access a union element by index (not user facing)
  • better compiler errors for unions
  • better documentation for unions
  • better error messages when accessing a union incorrectly
  • union checking is turned off with --no-checks
  • removes the deprecated Reflection.numFields
  • paratest with/without gasnet

This PR is not meant to make unions perfect, rather it incrementally
improves unions. Future work

[Reviewed by @DanilaFe]

Compare: Comparing 3fcba0aea2a4ab0af981160a191d0ef7dac487dc...8508316a9614f9c01e23ca05b5b53d17c6972a4d · chapel-lang/chapel · GitHub

Diff:
M compiler/AST/AggregateType.cpp
M compiler/AST/build.cpp
M compiler/AST/type.cpp
M compiler/include/driver.h
M compiler/include/type.h
M compiler/main/driver.cpp
M compiler/passes/ResolveScope.cpp
M compiler/passes/buildDefaultFunctions.cpp
M compiler/passes/convert-typed-uast.cpp
M compiler/resolution/expandVarArgs.cpp
M compiler/resolution/functionResolution.cpp
M compiler/resolution/preFold.cpp
M doc/rst/conf.py
M doc/rst/language/spec/unions.rst
M doc/rst/technotes/globalvars.rst
M frontend/include/chpl/framework/all-global-strings.h
M frontend/include/chpl/uast/compiler-globals-list.h
M frontend/lib/parsing/bison-chpl-lib.cpp
M frontend/lib/parsing/chpl.ypp
M frontend/lib/resolution/prims.cpp
M frontend/lib/uast/post-parse-checks.cpp
M frontend/test/parsing/testParseAggregate.cpp
M frontend/test/parsing/testParseAttributes.cpp
M frontend/test/resolution/testReflection.cpp
M man/chpl.rst
M modules/Makefile
M modules/internal/ChapelBase.chpl
M modules/internal/ChapelHashing.chpl
M modules/internal/ChapelStandard.chpl
A modules/internal/ChapelUnion.chpl
M modules/internal/fixInternalDocs.sh
M modules/standard/ChapelIO.chpl
M modules/standard/HaltWrappers.chpl
M modules/standard/Reflection.chpl
M test/classes/deitz/unions/union2.good
M test/classes/deitz/unions/union4.good
M test/classes/deitz/unions/union_method3.good
M test/compflags/bradc/help/userhelp.good
M test/compflags/ferguson/print-module-resolution.good
D test/deprecated/ReflectionNumFields.chpl
D test/deprecated/ReflectionNumFields.good
M test/io/serializers/deserialize-from.chpl
M test/param/ferguson/getfieldref.chpl
A test/types/unions/PREDIFF
A test/types/unions/accessByIndex-bad1.chpl
A test/types/unions/accessByIndex-bad1.good
A test/types/unions/accessByIndex-bad2.chpl
A test/types/unions/accessByIndex-bad2.good
A test/types/unions/accessByIndex-bad3.chpl
A test/types/unions/accessByIndex-bad3.good
A test/types/unions/accessByIndex-bad4.chpl
A test/types/unions/accessByIndex-bad4.good
A test/types/unions/accessByIndex.chpl
A test/types/unions/accessByIndex.good
A test/types/unions/bad-access1.chpl
A test/types/unions/bad-access1.good
A test/types/unions/bad-access2.chpl
A test/types/unions/bad-access2.good
A test/types/unions/bad-union-field.chpl
A test/types/unions/bad-union-field.good
A test/types/unions/bad-union-init-expr.chpl
A test/types/unions/bad-union-init-expr.good
A test/types/unions/bad-union-kw-syntax.chpl
A test/types/unions/bad-union-kw-syntax.good
A test/types/unions/badTypeAssign.chpl
A test/types/unions/badTypeAssign.good
A test/types/unions/badVisit1.chpl
A test/types/unions/badVisit1.good
A test/types/unions/badVisit2.chpl
A test/types/unions/badVisit2.good
A test/types/unions/badVisit3.chpl
A test/types/unions/badVisit3.good
A test/types/unions/badVisit4.chpl
A test/types/unions/badVisit4.good
A test/types/unions/badVisit5.chpl
A test/types/unions/badVisit5.good
A test/types/unions/one-elm.chpl
A test/types/unions/one-elm.good
A test/types/unions/selectPatterns.chpl
A test/types/unions/selectPatterns.good
A test/types/unions/statefulVisit.chpl
A test/types/unions/statefulVisit.good
M test/types/unions/union-in-list.chpl
M test/types/unions/union-readWrite.chpl
A test/types/unions/union-type-constraint.chpl
A test/types/unions/union-type-constraint.good
A test/types/unions/union-type-constraint.h
A test/types/unions/unionNesting.chpl
A test/types/unions/unionNesting.good
M test/users/ferguson/fielderator-ref.chpl
M test/users/ferguson/fielderator.chpl
A test/users/lydia/fieldNumToName.prediff
M test/users/lydia/fieldNumToNameError.chpl
M test/users/lydia/fieldNumToNameError.good
M util/chpl-completion.bash
https://github.com/chapel-lang/chapel/pull/28601.diff