modula2: new option -Wcase-enum and associated fixes

modula2: new option -Wcase-enum and associated fixes

This patch introduces -Wcase-enum which enumerates each missing
field in a case statement without an else clause providing the selector
expression type is an enum.

gcc/ChangeLog:

	* doc/gm2.texi (Compiler options): Document new option
	-Wcase-enum.

gcc/m2/ChangeLog:

	* gm2-compiler/M2CaseList.def (PushCase): Rename parameters
	r to rec and v to va.  Add expr parameter.
	(MissingCaseStatementBounds): New procedure function.
	* gm2-compiler/M2CaseList.mod (RangePair): Add expression.
	(PushCase): Rename parameters r to rec and v to va.  Add
	expr parameter.
	(RemoveRange): New procedure function.
	(SubBitRange): Detect the case when the range in the set matches
	lo..hi.
	(CheckLowHigh): New procedure.
	(ExcludeCaseRanges): Rename parameter c to cd.  Rename local
	variables q to cl and r to rp.
	(High): Remove.
	(Low): Remove.
	(DoEnumValues): Remove.
	(IncludeElement): New procedure.
	(IncludeElements): New procedure.
	(ErrorRangeEnum): New procedure.
	(ErrorRange): Remove.
	(ErrorRanges): Remove.
	(appendEnum): New procedure.
	(appendStr): New procedure.
	(EnumerateErrors): New procedure.
	(MissingCaseBounds): Re-implement.
	(InRangeList): Remove.
	(MissingCaseStatementBounds): New procedure function.
	(checkTypes): Re-format.
	(inRange): Re-format.
	(TypeCaseBounds): Re-format.
	* gm2-compiler/M2Error.mod (GetAnnounceScope): Add noscope to
	case label list.
	* gm2-compiler/M2GCCDeclare.mod: Replace ForeachFieldEnumerationDo
	with ForeachLocalSymDo.
	* gm2-compiler/M2Options.def (SetCaseEnumChecking): New procedure.
	(CaseEnumChecking): New variable.
	* gm2-compiler/M2Options.mod (SetCaseEnumChecking): New procedure.
	(Module initialization): set CaseEnumChecking to FALSE.
	* gm2-compiler/M2Quads.def (QuadOperator): Alphabetically ordered.
	* gm2-compiler/M2Quads.mod (IsBackReferenceConditional): Add else
	clause.
	(BuildCaseStart): Pass selector expression to InitCaseBounds.
	(CheckUninitializedVariablesAreUsed): Remove.
	(IsInlineWithinBlock): Remove.
	(AsmStatementsInBlock): Remove.
	(CheckVariablesInBlock): Remove commented code.
	(BeginVarient): Pass NulSym to InitCaseBounds.
	* gm2-compiler/M2Range.mod (FoldCaseBounds): New local variable
	errorGenerated.  Add call to MissingCaseStatementBounds.
	* gm2-compiler/P3Build.bnf (CaseEndStatement): Call ElseCase.
	* gm2-compiler/PCSymBuild.mod (InitDesExpr): Add else clause.
	(InitFunction): Add else clause.
	(InitConvert): Add else clause.
	(InitLeaf): Add else clause.
	(InitBinary): Add else clause.
	(InitUnary): Add else clause.
	* gm2-compiler/SymbolTable.def (GetNth): Re-write comment.
	(ForeachFieldEnumerationDo): Re-write comment stating alphabetical
	traversal.
	* gm2-compiler/SymbolTable.mod (GetNth): Re-write comment.
	Add case label for EnumerationSym and call GetItemFromList.
	(ForeachFieldEnumerationDo): Re-write comment stating alphabetical
	traversal.
	(SymEnumeration): Add ListOfFields used for declaration order.
	(MakeEnumeration): Initialize ListOfFields.
	(PutFieldEnumeration): Include Field in ListOfFields.
	* gm2-gcc/m2options.h (M2Options_SetCaseEnumChecking): New
	function.
	* gm2-lang.cc (gm2_langhook_handle_option): Add
	OPT_Wcase_enum case and call M2Options_SetCaseEnumChecking.
	* lang.opt (Wcase-enum): Add.

gcc/testsuite/ChangeLog:

	* gm2/switches/case/fail/missingclause.mod: New test.
	* gm2/switches/case/fail/switches-case-fail.exp: New test.
	* gm2/switches/case/pass/enumcase.mod: New test.
	* gm2/switches/case/pass/enumcase2.mod: New test.
	* gm2/switches/case/pass/switches-case-pass.exp: New test.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>