PR modula2/114548 gm2 fails to identify variable in a const expression

This patch introduces stricter checking within standard procedure
functions which detect whether paramaters are variable when used
in a const expression.

gcc/m2/ChangeLog:

	PR modula2/114548
	* gm2-compiler/M2Quads.mod (ConvertToAddress): Pass
	procedure, false parameters to BuildConvertFunction.
	(PushOne): Pass procedure, true parameters to
	BuildConvertFunction.
	Remove usused parameter internal.
	(BuildPseudoBy): Remove parameter to PushOne.
	(BuildIncProcedure): Ditto.
	(BuildDecProcedure): Ditto.
	(BuildFunctionCall): Add ConstExpr parameter to
	BuildPseudoFunctionCall.
	(BuildConstFunctionCall): Add procedure and true to
	BuildConvertFunction.
	(BuildPseudoFunctionCall): Add ConstExpr parameter.
	Pass ProcSym and ConstExpr to BuildLengthFunction,
	BuildConvertFunction, BuildOddFunction, BuildAbsFunction,
	BuildCapFunction, BuildValFunction, BuildChrFunction,
	BuildOrdFunction, BuildIntFunction, BuildTruncFunction,
	BuildFloatFunction, BuildAddAdrFunction, BuildSubAdrFunction,
	BuildDifAdrFunction, BuildCastFunction, BuildReFunction,
	BuildImFunction and BuildCmplxFunction.
	(BuildAddAdrFunction): Add ProcSym, ConstExpr parameters and
	check for constant parameters.
	(BuildSubAdrFunction): Ditto.
	(BuildDifAdrFunction): Ditto.
	(ConstExprError): Ditto.
	(BuildLengthFunction): Ditto.
	(BuildOddFunction): Ditto.
	(BuildAbsFunction): Ditto.
	(BuildCapFunction): Ditto.
	(BuildChrFunction): Ditto.
	(BuildOrdFunction): Ditto.
	(BuildIntFunction): Ditto.
	(BuildValFunction): Ditto.
	(BuildCastFunction): Ditto.
	(BuildConvertFunction): Ditto.
	(BuildTruncFunction): Ditto.
	(BuildFloatFunction): Ditto.
	(BuildReFunction): Ditto.
	(BuildImFunction): Ditto.
	(BuildCmplxFunction): Ditto.

gcc/testsuite/ChangeLog:

	PR modula2/114548
	* gm2/iso/const/fail/expression.mod: New test.
	* gm2/iso/const/fail/iso-const-fail.exp: New test.
	* gm2/iso/const/fail/testabs.mod: New test.
	* gm2/iso/const/fail/testaddadr.mod: New test.
	* gm2/iso/const/fail/testcap.mod: New test.
	* gm2/iso/const/fail/testcap2.mod: New test.
	* gm2/iso/const/fail/testchr.mod: New test.
	* gm2/iso/const/fail/testchr2.mod: New test.
	* gm2/iso/const/fail/testcmplx.mod: New test.
	* gm2/iso/const/fail/testfloat.mod: New test.
	* gm2/iso/const/fail/testim.mod: New test.
	* gm2/iso/const/fail/testint.mod: New test.
	* gm2/iso/const/fail/testlength.mod: New test.
	* gm2/iso/const/fail/testodd.mod: New test.
	* gm2/iso/const/fail/testord.mod: New test.
	* gm2/iso/const/fail/testre.mod: New test.
	* gm2/iso/const/fail/testtrunc.mod: New test.
	* gm2/iso/const/fail/testval.mod: New test.
	* gm2/iso/const/pass/constbool.mod: New test.
	* gm2/iso/const/pass/constbool2.mod: New test.
	* gm2/iso/const/pass/constbool3.mod: New test.

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

22 files changed, 553 insertions, 148 deletions

diff --git a/gcc/m2/gm2-compiler/M2Quads.mod b/gcc/m2/gm2-compiler/M2Quads.mod
index 891a76b..f2dfc83 100644
--- a/gcc/m2/gm2-compiler/M2Quads.mod
+++ b/gcc/m2/gm2-compiler/M2Quads.mod
@@ -3326,7 +3326,7 @@ BEGIN
       PushT (SkipType(type)) ;
       PushT (expr) ;
       PushT (2) ;          (* Two parameters *)
-      BuildConvertFunction ;
+      BuildConvertFunction (Convert, FALSE) ;
       PopT (expr)
    END ;
    RETURN( expr )
@@ -4356,7 +4356,7 @@ END BuildElsif2 ;
 *)
 
 PROCEDURE PushOne (tok: CARDINAL; type: CARDINAL;
-                   message: ARRAY OF CHAR; internal: BOOLEAN) ;
+                   message: ARRAY OF CHAR) ;
 VAR
    const: CARDINAL ;
 BEGIN
@@ -4378,7 +4378,7 @@ BEGIN
          PushT (type) ;
          PushTFtok (MakeConstLit (tok, MakeKey ('1'), ZType), ZType, tok) ;
          PushT (2) ;          (* Two parameters *)
-         BuildConvertFunction
+         BuildConvertFunction (Convert, TRUE)
       END
    ELSE
       const := MakeConstLit (tok, MakeKey ('1'), type) ;
@@ -4413,7 +4413,7 @@ BEGIN
       PushTtok (type, tok) ;
       PushTtok (MakeConstLit (tok, MakeKey ('0'), ZType), tok) ;
       PushT (2) ;          (* Two parameters *)
-      BuildConvertFunction
+      BuildConvertFunction (Convert, TRUE)
    ELSE
       PushTFtok (MakeConstLit (tok, MakeKey ('0'), type), type, tok)
    END
@@ -4456,7 +4456,7 @@ BEGIN
       type := ZType
    END ;
    PushOne (dotok, type,
-            'the implied {%kFOR} loop increment will cause an overflow {%1ad}', TRUE)
+            'the implied {%kFOR} loop increment will cause an overflow {%1ad}')
 END BuildPseudoBy ;
 
 
@@ -7246,7 +7246,7 @@ BEGIN
          PushT (dtype) ;
          PushT (expr) ;
          PushT (2) ;          (* Two parameters *)
-         BuildConvertFunction ;
+         BuildConvertFunction (Convert, FALSE) ;
          doBuildBinaryOp (FALSE, TRUE)
       ELSE
          IF tok=PlusTok
@@ -7313,7 +7313,7 @@ BEGIN
             OperandSym := DereferenceLValue (OperandTok (1), OperandT (1))
          ELSE
             PushOne (proctok, dtype,
-                     'the {%EkINC} will cause an overflow {%1ad}', FALSE) ;
+                     'the {%EkINC} will cause an overflow {%1ad}') ;
 	    PopT (OperandSym)
          END ;
 
@@ -7386,7 +7386,7 @@ BEGIN
             OperandSym := DereferenceLValue (OperandTok (1), OperandT (1))
          ELSE
             PushOne (proctok, dtype,
-                     'the {%EkDEC} will cause an overflow {%1ad}', FALSE) ;
+                     'the {%EkDEC} will cause an overflow {%1ad}') ;
 	    PopT (OperandSym)
          END ;
 
@@ -7680,7 +7680,7 @@ BEGIN
    IF IsUnknown (ProcSym)
    THEN
       paramtok := OperandTtok (1) ;
-      combinedtok := MakeVirtualTok (functok, functok, paramtok) ;
+      combinedtok := MakeVirtual2Tok (functok, paramtok) ;
       MetaErrorT1 (functok, 'procedure function {%1Ea} is undefined', ProcSym) ;
       PopN (NoOfParam + 2) ;
       (* Fake return value to continue compiling.  *)
@@ -7693,7 +7693,7 @@ BEGIN
          IsPseudoBaseFunction (ProcSym)
    THEN
       ManipulatePseudoCallParameters ;
-      BuildPseudoFunctionCall
+      BuildPseudoFunctionCall (ConstExpr)
    ELSE
       BuildRealFunctionCall (functok, ConstExpr)
    END
@@ -7767,7 +7767,7 @@ BEGIN
             PushTtok (ProcSym, functok) ;
             PushTtok (ConstExpression, paramtok) ;
             PushT (2) ;  (* Two parameters.  *)
-            BuildConvertFunction
+            BuildConvertFunction (Convert, TRUE)
          ELSE
             MetaErrorT0 (functok, '{%E}a constant type conversion can only have one argument')
          END
@@ -7952,7 +7952,7 @@ END BuildRealFunctionCall ;
 
 *)
 
-PROCEDURE BuildPseudoFunctionCall ;
+PROCEDURE BuildPseudoFunctionCall (ConstExpr: BOOLEAN) ;
 VAR
    NoOfParam,
    ProcSym  : CARDINAL ;
@@ -7961,13 +7961,13 @@ BEGIN
    ProcSym := OperandT (NoOfParam+1) ;
    ProcSym := SkipConst (ProcSym) ;
    PushT (NoOfParam) ;
-   (* Compile time stack restored to entry state *)
+   (* Compile time stack restored to entry state.  *)
    IF ProcSym = High
    THEN
       BuildHighFunction
    ELSIF ProcSym = LengthS
    THEN
-      BuildLengthFunction
+      BuildLengthFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Adr
    THEN
       BuildAdrFunction
@@ -7982,34 +7982,34 @@ BEGIN
       BuildTBitSizeFunction
    ELSIF ProcSym = Convert
    THEN
-      BuildConvertFunction
+      BuildConvertFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Odd
    THEN
-      BuildOddFunction
+      BuildOddFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Abs
    THEN
-      BuildAbsFunction
+      BuildAbsFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Cap
    THEN
-      BuildCapFunction
+      BuildCapFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Val
    THEN
-      BuildValFunction
+      BuildValFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Chr
    THEN
-      BuildChrFunction
+      BuildChrFunction (ProcSym, ConstExpr)
    ELSIF IsOrd (ProcSym)
    THEN
-      BuildOrdFunction (ProcSym)
+      BuildOrdFunction (ProcSym, ConstExpr)
    ELSIF IsInt (ProcSym)
    THEN
-      BuildIntFunction (ProcSym)
+      BuildIntFunction (ProcSym, ConstExpr)
    ELSIF IsTrunc (ProcSym)
    THEN
-      BuildTruncFunction (ProcSym)
+      BuildTruncFunction (ProcSym, ConstExpr)
    ELSIF IsFloat (ProcSym)
    THEN
-      BuildFloatFunction (ProcSym)
+      BuildFloatFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Min
    THEN
       BuildMinFunction
@@ -8018,16 +8018,16 @@ BEGIN
       BuildMaxFunction
    ELSIF ProcSym = AddAdr
    THEN
-      BuildAddAdrFunction
+      BuildAddAdrFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = SubAdr
    THEN
-      BuildSubAdrFunction
+      BuildSubAdrFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = DifAdr
    THEN
-      BuildDifAdrFunction
+      BuildDifAdrFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Cast
    THEN
-      BuildCastFunction
+      BuildCastFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Shift
    THEN
       BuildShiftFunction
@@ -8039,13 +8039,13 @@ BEGIN
       BuildMakeAdrFunction
    ELSIF ProcSym = Re
    THEN
-      BuildReFunction
+      BuildReFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Im
    THEN
-      BuildImFunction
+      BuildImFunction (ProcSym, ConstExpr)
    ELSIF ProcSym = Cmplx
    THEN
-      BuildCmplxFunction
+      BuildCmplxFunction (ProcSym, ConstExpr)
    ELSE
       InternalError  ('pseudo function not implemented yet')
    END
@@ -8078,10 +8078,11 @@ END BuildPseudoFunctionCall ;
                          |----------------|         |------------|
 *)
 
-PROCEDURE BuildAddAdrFunction ;
+PROCEDURE BuildAddAdrFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    combinedtok,
    functok,
+   vartok,
    optok      : CARDINAL ;
    opa,
    ReturnVar,
@@ -8094,11 +8095,18 @@ BEGIN
    IF NoOfParam=2
    THEN
       VarSym := OperandT (2) ;
+      vartok := OperandTok (2) ;
       OperandSym := OperandT (1) ;
       optok := OperandTok (1) ;
-      combinedtok := MakeVirtualTok (functok, functok, optok) ;
+      combinedtok := MakeVirtual2Tok (functok, optok) ;
       PopN (NoOfParam + 1) ;
-      IF IsVar (VarSym)
+      IF ConstExprError (ProcSym, VarSym, vartok, ConstExpr) OR
+         ConstExprError (ProcSym, OperandSym, optok, ConstExpr)
+      THEN
+         (* Fake return result.  *)
+         PushTFtok (MakeConstLit (combinedtok, MakeKey('0'), Address),
+                    Address, combinedtok)
+      ELSIF IsVar (VarSym)
       THEN
          IF IsReallyPointer (VarSym) OR (GetSType (VarSym) = Address)
          THEN
@@ -8119,9 +8127,10 @@ BEGIN
          PushTFtok (MakeConstLit (combinedtok, MakeKey('0'), Address), Address, combinedtok)
       END
    ELSE
-      MetaErrorT0 (functok, '{%E}SYSTEM procedure ADDADR expects 2 parameters') ;
-      PopN (NoOfParam + 1) ;
-      PushTFtok (MakeConstLit (functok, MakeKey ('0'), Address), Address, functok)
+      MetaErrorT0 (functok,
+                   '{%E}SYSTEM procedure {%EkADDADR} expects 2 parameters') ;
+      PopN (NoOfParam+1) ;
+      PushTFtok (MakeConstLit (functok, MakeKey('0'), Address), Address, functok)
    END
 END BuildAddAdrFunction ;
 
@@ -8152,7 +8161,7 @@ END BuildAddAdrFunction ;
                          |----------------|         |------------|
 *)
 
-PROCEDURE BuildSubAdrFunction ;
+PROCEDURE BuildSubAdrFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    functok,
    combinedtok,
@@ -8166,15 +8175,21 @@ VAR
 BEGIN
    PopT (NoOfParam) ;
    functok := OperandTtok (NoOfParam + 1) ;
-   OperandSym := OperandT (1) ;
-   optok := OperandTok (1) ;
    IF NoOfParam = 2
    THEN
+      optok := OperandTok (1) ;
+      OperandSym := OperandT (1) ;
       VarSym := OperandT (2) ;
       vartok := OperandTok (2) ;
       combinedtok := MakeVirtualTok (functok, functok, optok) ;
       PopN (NoOfParam + 1) ;
-      IF IsVar (VarSym)
+      IF ConstExprError (ProcSym, VarSym, vartok, ConstExpr) OR
+         ConstExprError (ProcSym, OperandSym, optok, ConstExpr)
+      THEN
+         (* Fake return result.  *)
+         PushTFtok (MakeConstLit (combinedtok, MakeKey('0'), Address),
+                    Address, combinedtok)
+      ELSIF IsVar (VarSym)
       THEN
          IF IsReallyPointer (VarSym) OR (GetSType (VarSym) = Address)
          THEN
@@ -8197,11 +8212,10 @@ BEGIN
          PushTFtok (MakeConstLit (combinedtok, MakeKey ('0'), Address), Address, combinedtok)
       END
    ELSE
-      combinedtok := MakeVirtualTok (functok, functok, optok) ;
       MetaErrorT0 (functok,
                    '{%E}SYSTEM procedure {%EkSUBADR} expects 2 parameters') ;
       PopN (NoOfParam+1) ;
-      PushTFtok (MakeConstLit (combinedtok, MakeKey('0'), Address), Address, combinedtok)
+      PushTFtok (MakeConstLit (functok, MakeKey('0'), Address), Address, functok)
    END
 END BuildSubAdrFunction ;
 
@@ -8233,7 +8247,7 @@ END BuildSubAdrFunction ;
                          |----------------|         |------------|
 *)
 
-PROCEDURE BuildDifAdrFunction ;
+PROCEDURE BuildDifAdrFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    functok,
    optok,
@@ -8247,15 +8261,26 @@ VAR
 BEGIN
    PopT (NoOfParam) ;
    functok := OperandTtok (NoOfParam + 1) ;
-   OperandSym := OperandT (1) ;
-   optok := OperandTok (1) ;
+   IF NoOfParam >= 1
+   THEN
+      OperandSym := OperandT (1) ;
+      optok := OperandTok (1)
+   ELSE
+      optok := functok
+   END ;
    IF NoOfParam = 2
    THEN
       VarSym := OperandT (2) ;
       vartok := OperandTok (2) ;
       combinedtok := MakeVirtualTok (functok, functok, optok) ;
       PopN (NoOfParam + 1) ;
-      IF IsVar (VarSym)
+      IF ConstExprError (ProcSym, VarSym, vartok, ConstExpr) OR
+         ConstExprError (ProcSym, OperandSym, optok, ConstExpr)
+      THEN
+         (* Fake return result.  *)
+         PushTFtok (MakeConstLit (combinedtok, MakeKey('0'), Integer),
+                    Integer, combinedtok)
+      ELSIF IsVar (VarSym)
       THEN
          IF IsReallyPointer (VarSym) OR (GetSType (VarSym) = Address)
          THEN
@@ -8273,7 +8298,7 @@ BEGIN
                PushTtok (Integer, functok) ;
                PushTtok (TempVar, vartok) ;
                PushT (2) ;          (* Two parameters *)
-               BuildConvertFunction
+               BuildConvertFunction (Convert, ConstExpr)
             ELSE
                MetaError1 ('the second parameter to {%EkDIFADR} {%1Ea} must be a variable of type ADDRESS or a {%EkPOINTER}, rather than a {%1Etsd}',
                            OperandSym) ;
@@ -8290,8 +8315,8 @@ BEGIN
          PushTFtok (MakeConstLit (combinedtok, MakeKey('0'), Integer), Integer, combinedtok)
       END
    ELSE
-      combinedtok := MakeVirtualTok (functok, functok, optok) ;
-      MetaErrorT0 (functok, '{%E}SYSTEM procedure {%EkDIFADR} expects 2 parameters') ;
+      combinedtok := MakeVirtual2Tok (functok, optok) ;
+      MetaErrorT0 (combinedtok, '{%E}SYSTEM procedure {%EkDIFADR} expects 2 parameters') ;
       PopN (NoOfParam+1) ;
       PushTFtok (MakeConstLit (combinedtok, MakeKey('0'), Integer), Integer, combinedtok)
    END
@@ -8488,6 +8513,24 @@ END GetQualidentImport ;
 
 
 (*
+   ConstExprError - return TRUE if a constant expression is being built and Var is a variable.
+*)
+
+PROCEDURE ConstExprError (Func, Var: CARDINAL; optok: CARDINAL; ConstExpr: BOOLEAN) : BOOLEAN ;
+BEGIN
+   IF ConstExpr AND IsVar (Var)
+   THEN
+      MetaErrorT2 (optok,
+                   'the procedure function {%1Ea} is being called from within a constant expression and therefore the parameter {%2a} must be a constant, seen a {%2da}',
+                   Func, Var) ;
+      RETURN TRUE
+   ELSE
+      RETURN FALSE
+   END
+END ConstExprError ;
+
+
+(*
    DeferMakeLengthConst - creates a constant which contains the length of string, sym.
 *)
 
@@ -8521,7 +8564,7 @@ END DeferMakeLengthConst ;
 
 *)
 
-PROCEDURE BuildLengthFunction ;
+PROCEDURE BuildLengthFunction  (Function: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    combinedtok,
    paramtok,
@@ -8545,7 +8588,7 @@ BEGIN
    END ;
    IF NoOfParam >= 1
    THEN
-      combinedtok := MakeVirtualTok (paramtok, functok, paramtok) ;
+      combinedtok := MakeVirtual2Tok (functok, paramtok) ;
       IF IsConst (Param) AND (GetSType (Param) = Char)
       THEN
          PopT (NoOfParam) ;
@@ -8563,16 +8606,22 @@ BEGIN
          IF (ProcSym # NulSym) AND IsProcedure (ProcSym)
          THEN
             PopT (NoOfParam) ;
-            IF IsConst (OperandT (1))
+            IF IsConst (Param)
             THEN
-               (* we can fold this in M2GenGCC.  *)
+               (* This can be folded in M2GenGCC.  *)
                ReturnVar := MakeTemporary (combinedtok, ImmediateValue) ;
                PutVar (ReturnVar, Cardinal) ;
-               GenQuad (StandardFunctionOp, ReturnVar, ProcSym, OperandT (1)) ;
+               GenQuad (StandardFunctionOp, ReturnVar, ProcSym, Param) ;
                PopN (NoOfParam + 1) ;
                PushTtok (ReturnVar, combinedtok)
+            ELSIF ConstExprError (Function, Param, paramtok, ConstExpr)
+            THEN
+               (* Fake a result as we have detected and reported an error.  *)
+               PopN (NoOfParam + 1) ;
+               ReturnVar := MakeConstLit (combinedtok, MakeKey ('1'), Cardinal) ;
+               PushTtok (ReturnVar, combinedtok)
             ELSE
-               (* no we must resolve this at runtime or in the GCC optimizer.  *)
+               (* We must resolve this at runtime or in the GCC optimizer.  *)
                PopTF (Param, Type);
 	       PopN (NoOfParam) ;
 	       PushTtok (ProcSym, functok) ;
@@ -8627,7 +8676,7 @@ END BuildLengthFunction ;
                       |----------------|
 *)
 
-PROCEDURE BuildOddFunction ;
+PROCEDURE BuildOddFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    combinedtok,
    optok,
@@ -8642,7 +8691,11 @@ BEGIN
       Var := OperandT (1) ;
       optok := OperandTok (1) ;
       combinedtok := MakeVirtualTok (functok, functok, optok) ;
-      IF IsVar(Var) OR IsConst(Var)
+      IF ConstExprError (ProcSym, Var, optok, ConstExpr)
+      THEN
+         (* Nothing to do.  *)
+         PushTtok (False, combinedtok)
+      ELSIF IsVar(Var) OR IsConst(Var)
       THEN
          PopN (NoOfParam + 1) ;
          (*
@@ -8726,13 +8779,12 @@ END BuildOddFunction ;
                       |----------------|
 *)
 
-PROCEDURE BuildAbsFunction ;
+PROCEDURE BuildAbsFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    vartok,
    functok,
    combinedtok: CARDINAL ;
    NoOfParam,
-   ProcSym,
    Res, Var : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
@@ -8741,12 +8793,16 @@ BEGIN
    THEN
       Var := OperandT (1) ;
       vartok := OperandTok (1) ;
+      PopN (NoOfParam + 1) ;
       combinedtok := MakeVirtualTok (functok, functok, vartok) ;
-      IF IsVar(Var) OR IsConst(Var)
+      IF ConstExprError (ProcSym, Var, vartok, ConstExpr)
+      THEN
+         (* Create fake result.  *)
+         Res := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
+         PutVar (Res, GetSType (Var)) ;
+         PushTFtok (Res, GetSType (Var), combinedtok)
+      ELSIF IsVar(Var) OR IsConst(Var)
       THEN
-         ProcSym := OperandT (NoOfParam + 1) ;
-         PopN (NoOfParam + 1) ;
-
          Res := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
          PutVar (Res, GetSType (Var)) ;
 
@@ -8787,13 +8843,12 @@ END BuildAbsFunction ;
                       |----------------|         |-------------|
 *)
 
-PROCEDURE BuildCapFunction ;
+PROCEDURE BuildCapFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    optok,
    functok,
    combinedtok: CARDINAL ;
    NoOfParam,
-   ProcSym,
    Res, Var : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
@@ -8802,12 +8857,17 @@ BEGIN
    THEN
       Var := OperandT (1) ;
       optok := OperandTok (1) ;
-      IF IsVar (Var) OR IsConst (Var)
+      PopN (NoOfParam + 1) ;
+      IF ConstExprError (ProcSym, Var, optok, ConstExpr)
       THEN
-         ProcSym := OperandT (NoOfParam + 1) ;
-         PopN (NoOfParam + 1) ;
-
-         combinedtok := MakeVirtualTok (functok, functok, optok) ;
+         (* Create fake result.  *)
+         combinedtok := MakeVirtual2Tok (functok, optok) ;
+         Res := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
+         PutVar (Res, Char) ;
+         PushTFtok (Res, Char, combinedtok)
+      ELSIF IsVar (Var) OR IsConst (Var)
+      THEN
+         combinedtok := MakeVirtual2Tok (functok, optok) ;
          Res := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
          PutVar (Res, Char) ;
          GenQuadO (combinedtok, StandardFunctionOp, Res, ProcSym, Var, FALSE) ;
@@ -8858,10 +8918,12 @@ END BuildCapFunction ;
                       |----------------|
 *)
 
-PROCEDURE BuildChrFunction ;
+PROCEDURE BuildChrFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    functok,
+   combinedtok,
    optok      : CARDINAL ;
+   ReturnVar,
    NoOfParam,
    Var        : CARDINAL ;
 BEGIN
@@ -8871,9 +8933,16 @@ BEGIN
    THEN
       Var := OperandT (1) ;
       optok := OperandTok (1) ;
-      IF IsVar (Var) OR IsConst (Var)
+      PopN (NoOfParam + 1) ;
+      IF ConstExprError (ProcSym, Var, optok, ConstExpr)
+      THEN
+         (* Generate fake result.  *)
+         combinedtok := MakeVirtual2Tok (functok, optok) ;
+         ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
+         PutVar (ReturnVar, Char) ;
+         PushTFtok (ReturnVar, Char, combinedtok)
+      ELSIF IsVar (Var) OR IsConst (Var)
       THEN
-         PopN (NoOfParam + 1) ;
          (*
             Build macro: CONVERT( CHAR, Var )
          *)
@@ -8881,7 +8950,7 @@ BEGIN
          PushTtok (Char, functok) ;
          PushTtok (Var, optok) ;
          PushT (2) ;          (* Two parameters *)
-         BuildConvertFunction
+         BuildConvertFunction (Convert, ConstExpr)
       ELSE
          MetaErrorT1 (optok,
                       'the parameter to {%AkCHR} must be a variable or constant, seen {%1ad}',
@@ -8928,12 +8997,14 @@ END BuildChrFunction ;
                       |----------------|
 *)
 
-PROCEDURE BuildOrdFunction (Sym: CARDINAL) ;
+PROCEDURE BuildOrdFunction (Sym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
+   combinedtok,
    functok,
-   optok    : CARDINAL ;
+   optok      : CARDINAL ;
+   ReturnVar,
    NoOfParam,
-   Type, Var: CARDINAL ;
+   Type, Var  : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
    functok := OperandTok (NoOfParam + 1) ;
@@ -8941,10 +9012,17 @@ BEGIN
    THEN
       Var := OperandT (1) ;
       optok := OperandTok (1) ;
-      IF IsVar (Var) OR IsConst (Var)
+      PopN (NoOfParam + 1) ;
+      IF ConstExprError (Sym, Var, optok, ConstExpr)
+      THEN
+         (* Generate fake result.  *)
+         combinedtok := MakeVirtual2Tok (functok, optok) ;
+         ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
+         PutVar (ReturnVar, Cardinal) ;
+         PushTFtok (ReturnVar, Cardinal, combinedtok)
+      ELSIF IsVar (Var) OR IsConst (Var)
       THEN
          Type := GetSType (Sym) ;
-         PopN (NoOfParam + 1) ;
          (*
             Build macro: CONVERT( CARDINAL, Var )
          *)
@@ -8952,7 +9030,7 @@ BEGIN
          PushTtok (Type, optok) ;
          PushTtok (Var, optok) ;
          PushT (2) ;          (* Two parameters *)
-         BuildConvertFunction
+         BuildConvertFunction (Convert, ConstExpr)
       ELSE
          MetaErrorT2 (optok,
                       'the parameter to {%1Aa} must be a variable or constant, seen {%2ad}',
@@ -8999,11 +9077,12 @@ END BuildOrdFunction ;
                       |----------------|
 *)
 
-PROCEDURE BuildIntFunction (Sym: CARDINAL) ;
+PROCEDURE BuildIntFunction (Sym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    combinedtok,
    functok,
    optok      : CARDINAL ;
+   ReturnVar,
    NoOfParam,
    Type, Var  : CARDINAL ;
 BEGIN
@@ -9013,16 +9092,23 @@ BEGIN
    THEN
       Var := OperandT (1) ;
       optok := OperandTok (1) ;
-      IF IsVar (Var) OR IsConst (Var)
+      PopN (NoOfParam + 1) ;
+      IF ConstExprError (Sym, Var, optok, ConstExpr)
+      THEN
+         (* Generate fake result.  *)
+         combinedtok := MakeVirtual2Tok (functok, optok) ;
+         ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
+         PutVar (ReturnVar, Integer) ;
+         PushTFtok (ReturnVar, Integer, combinedtok)
+      ELSIF IsVar (Var) OR IsConst (Var)
       THEN
          Type := GetSType (Sym) ;  (* return type of function *)
-         PopN (NoOfParam + 1) ;
          (* Build macro: CONVERT( CARDINAL, Var ).  *)
          PushTFtok (Convert, NulSym, functok) ;
          PushTtok (Type, functok) ;
          PushTtok (Var, optok) ;
          PushT (2) ;          (* Two parameters *)
-         BuildConvertFunction
+         BuildConvertFunction (Convert, ConstExpr)
       ELSE
          combinedtok := MakeVirtualTok (functok, optok, optok) ;
          MetaErrorT2 (optok,
@@ -9305,15 +9391,16 @@ END BuildRotateFunction ;
                       |----------------|
 *)
 
-PROCEDURE BuildValFunction ;
+PROCEDURE BuildValFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
-   functok  : CARDINAL ;
+   combinedtok,
+   functok    : CARDINAL ;
+   ReturnVar,
    NoOfParam,
-   ProcSym,
-   Exp, Type: CARDINAL ;
+   Exp, Type  : CARDINAL ;
    tok, r,
    typetok,
-   exptok   : CARDINAL ;
+   exptok     : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
    functok := OperandTok (NoOfParam + 1) ;
@@ -9330,6 +9417,13 @@ BEGIN
                       'undeclared type found in builtin procedure function {%AkVAL} {%1ad}',
                       Type)
          (* non recoverable error.  *)
+      ELSIF ConstExprError (ProcSym, Exp, exptok, ConstExpr)
+      THEN
+         (* Generate fake result.  *)
+         combinedtok := MakeVirtualTok (functok, functok, exptok) ;
+         ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Exp))) ;
+         PutVar (ReturnVar, Type) ;
+         PushTFtok (ReturnVar, Type, combinedtok)
       ELSIF (IsSet (Type) OR IsEnumeration (Type) OR IsSubrange (Type) OR
              IsType (Type) OR IsPointer (Type) OR IsProcType (Type)) AND
              (IsVar (Exp) OR IsConst (Exp) OR IsProcedure (Exp))
@@ -9341,7 +9435,7 @@ BEGIN
          PushTtok (Type, typetok) ;
          PushTtok (Exp, exptok) ;
          PushT (2) ;          (* Two parameters *)
-         BuildConvertFunction
+         BuildConvertFunction (Convert, ConstExpr)
       ELSE
          (* not sensible to try and recover when we dont know the return type.  *)
          MetaErrorT0 (functok,
@@ -9390,16 +9484,15 @@ END BuildValFunction ;
                        |----------------|
 *)
 
-PROCEDURE BuildCastFunction ;
+PROCEDURE BuildCastFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    combinedtok,
+   exptok,
    typetok,
-   functok,
-   vartok     : CARDINAL ;
-   n          : Name ;
+   functok    : CARDINAL ;
    ReturnVar,
    NoOfParam,
-   Var, Type  : CARDINAL ;
+   Exp, Type  : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
    functok := OperandTok (NoOfParam + 1) ;
@@ -9407,32 +9500,40 @@ BEGIN
    THEN
       Type := OperandT (2) ;
       typetok := OperandTok (2) ;
-      Var := OperandT (1) ;
-      vartok := OperandTok (1) ;
+      Exp := OperandT (1) ;
+      exptok := OperandTok (1) ;
       IF IsUnknown (Type)
       THEN
-         n := GetSymName (Type) ;
-         WriteFormat1 ('undeclared type found in CAST (%a)', n)
+         (* we cannot recover if we dont have a type.  *)
+         MetaErrorT1 (typetok, 'undeclared type {%1Aad} found in {%kCAST}', Type)
+         (* non recoverable error.  *)
+      ELSIF ConstExprError (ProcSym, Exp, exptok, ConstExpr)
+      THEN
+         (* Generate fake result.  *)
+         combinedtok := MakeVirtualTok (functok, functok, exptok) ;
+         ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Exp))) ;
+         PutVar (ReturnVar, Type) ;
+         PushTFtok (ReturnVar, Type, combinedtok)
       ELSIF IsSet (Type) OR IsEnumeration (Type) OR IsSubrange (Type) OR IsType (Type) OR
             IsPointer (Type) OR IsArray (Type) OR IsProcType (Type)
       THEN
-         IF IsConst (Var)
+         IF IsConst (Exp)
          THEN
             PopN (NoOfParam+1) ;
             (*
                Build macro: Type( Var )
             *)
             PushTFtok (Type, NulSym, typetok) ;
-            PushTtok (Var, vartok) ;
+            PushTtok (Exp, exptok) ;
             PushT (1) ;          (* one parameter *)
             BuildTypeCoercion
-         ELSIF IsVar (Var) OR IsProcedure (Var)
+         ELSIF IsVar (Exp) OR IsProcedure (Exp)
          THEN
             PopN (NoOfParam + 1) ;
-            combinedtok := MakeVirtualTok (functok, functok, vartok) ;
+            combinedtok := MakeVirtual2Tok (functok, exptok) ;
             ReturnVar := MakeTemporary (combinedtok, RightValue) ;
             PutVar (ReturnVar, Type) ;
-            GenQuadO (combinedtok, CastOp, ReturnVar, Type, Var, FALSE) ;
+            GenQuadO (combinedtok, CastOp, ReturnVar, Type, Exp, FALSE) ;
             PushTFtok (ReturnVar, Type, combinedtok)
          ELSE
             (* not sensible to try and recover when we dont know the return type.  *)
@@ -9489,7 +9590,7 @@ END BuildCastFunction ;
                           with a type Param1.
 *)
 
-PROCEDURE BuildConvertFunction ;
+PROCEDURE BuildConvertFunction (ProcSym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    combinedtok,
    functok,
@@ -9497,7 +9598,6 @@ VAR
    exptok     : CARDINAL ;
    t, r,
    Exp, Type,
-   ProcSym,
    NoOfParam,
    ReturnVar  : CARDINAL ;
 BEGIN
@@ -9519,6 +9619,13 @@ BEGIN
          (* we cannot recover if we dont have a type.  *)
          MetaErrorT1 (typetok, 'unknown {%1Ad} {%1ad} found in {%kCONVERT}', Exp)
          (* non recoverable error.  *)
+      ELSIF ConstExprError (ProcSym, Exp, exptok, ConstExpr)
+      THEN
+         (* Generate fake result.  *)
+         combinedtok := MakeVirtualTok (functok, functok, exptok) ;
+         ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Exp))) ;
+         PutVar (ReturnVar, Type) ;
+         PushTFtok (ReturnVar, Type, combinedtok)
       ELSIF (IsSet (Type) OR IsEnumeration (Type) OR IsSubrange (Type) OR
              IsType (Type) OR IsPointer (Type) OR IsProcType (Type) OR IsRecord (Type)) AND
             (IsVar (Exp) OR IsConst (Exp) OR IsProcedure (Exp))
@@ -9807,14 +9914,16 @@ END BuildMaxFunction ;
                         |----------------|
 *)
 
-PROCEDURE BuildTruncFunction (Sym: CARDINAL) ;
+PROCEDURE BuildTruncFunction (Sym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
+   combinedtok,
    vartok,
-   functok  : CARDINAL ;
-   NoOfParam: CARDINAL ;
+   functok    : CARDINAL ;
+   NoOfParam  : CARDINAL ;
+   ReturnVar,
    ProcSym,
    Type,
-   Var      : CARDINAL ;
+   Var        : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
    Assert (IsTrunc (OperandT (NoOfParam+1))) ;
@@ -9828,7 +9937,14 @@ BEGIN
          vartok := OperandTtok (1) ;
          Type := GetSType (Sym) ;
          PopN (NoOfParam + 1) ;    (* destroy arguments to this function *)
-         IF IsVar (Var) OR IsConst (Var)
+         IF ConstExprError (Sym, Var, vartok, ConstExpr)
+         THEN
+            (* Generate fake result.  *)
+            combinedtok := MakeVirtual2Tok (functok, vartok) ;
+            ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
+            PutVar (ReturnVar, Type) ;
+            PushTFtok (ReturnVar, Type, combinedtok)
+         ELSIF IsVar (Var) OR IsConst (Var)
          THEN
             IF IsRealType (GetSType (Var))
             THEN
@@ -9837,7 +9953,7 @@ BEGIN
                PushTtok (Type, functok) ;
                PushTtok (Var, vartok) ;
                PushT (2) ;          (* two parameters *)
-               BuildConvertFunction
+               BuildConvertFunction (Convert, ConstExpr)
             ELSE
                MetaErrorT1 (functok,
                             'argument to {%1Ead} must be a float point type', Sym) ;
@@ -9894,14 +10010,16 @@ END BuildTruncFunction ;
                         |----------------|
 *)
 
-PROCEDURE BuildFloatFunction (Sym: CARDINAL) ;
+PROCEDURE BuildFloatFunction (Sym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
+   combinedtok,
    vartok,
-   functok  : CARDINAL ;
-   NoOfParam: CARDINAL ;
+   functok    : CARDINAL ;
+   NoOfParam  : CARDINAL ;
+   ReturnVar,
    Type,
    Var,
-   ProcSym  : CARDINAL ;
+   ProcSym    : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
    functok := OperandTtok (NoOfParam + 1) ;
@@ -9913,15 +10031,22 @@ BEGIN
       THEN
          Var := OperandT (1) ;
          vartok := OperandTtok (1) ;
-         IF IsVar (Var) OR IsConst (Var)
+         PopN (NoOfParam + 1) ;    (* destroy arguments to this function.  *)
+         IF ConstExprError (Sym, Var, vartok, ConstExpr)
+         THEN
+            (* Generate fake result.  *)
+            combinedtok := MakeVirtual2Tok (functok, vartok) ;
+            ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
+            PutVar (ReturnVar, Type) ;
+            PushTFtok (ReturnVar, Type, combinedtok)
+         ELSIF IsVar (Var) OR IsConst (Var)
          THEN
-            PopN (NoOfParam + 1) ;    (* destroy arguments to this function.  *)
             (* build macro: CONVERT (REAL, Var).  *)
             PushTFtok (ProcSym, NulSym, functok) ;
             PushTtok (Type, functok) ;
             PushTtok (Var, vartok) ;
             PushT(2) ;          (* two parameters.  *)
-            BuildConvertFunction
+            BuildConvertFunction (ProcSym, ConstExpr)
          ELSE
             MetaErrorT1 (vartok,
                          'argument to {%1Ead} must be a variable or constant', ProcSym) ;
@@ -9931,6 +10056,7 @@ BEGIN
          InternalError  ('CONVERT procedure not found for FLOAT substitution')
       END
    ELSE
+      PopN (NoOfParam + 1) ;    (* destroy arguments to this function.  *)
       MetaErrorT1 (functok,
                    'the builtin procedure function {%1Ead} only has one parameter',
                    Sym) ;
@@ -9965,7 +10091,7 @@ END BuildFloatFunction ;
                         |----------------|
 *)
 
-PROCEDURE BuildReFunction ;
+PROCEDURE BuildReFunction (Sym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    func,
    combinedtok,
@@ -9973,6 +10099,7 @@ VAR
    functok    : CARDINAL ;
    NoOfParam  : CARDINAL ;
    ReturnVar,
+   Type,
    Var        : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
@@ -9983,15 +10110,22 @@ BEGIN
       Var := OperandT (1) ;
       vartok := OperandTok (1) ;
       combinedtok := MakeVirtualTok (functok, functok, vartok) ;
-      IF IsVar(Var) OR IsConst(Var)
+      Type := ComplexToScalar (GetDType (Var)) ;
+      PopN (NoOfParam+1) ;  (* destroy arguments to this function *)
+      IF ConstExprError (Sym, Var, vartok, ConstExpr)
       THEN
+         (* Generate fake result.  *)
+         combinedtok := MakeVirtual2Tok (functok, vartok) ;
          ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
-         PutVar (ReturnVar, ComplexToScalar (GetDType (Var))) ;
+         PutVar (ReturnVar, Type) ;
+         PushTFtok (ReturnVar, Type, combinedtok)
+      ELSIF IsVar(Var) OR IsConst(Var)
+      THEN
+         ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
+         PutVar (ReturnVar, Type) ;
          GenQuadO (combinedtok, StandardFunctionOp, ReturnVar, Re, Var, FALSE) ;
-         PopN (NoOfParam+1) ;  (* destroy arguments to this function *)
-         PushTFtok (ReturnVar, GetSType (ReturnVar), combinedtok)
+         PushTFtok (ReturnVar, Type, combinedtok)
       ELSE
-         PopN (NoOfParam+1) ;  (* destroy arguments to this function *)
          PushTFtok (MakeConstLit (combinedtok, MakeKey ('1.0'), RType), RType, combinedtok) ;
          MetaErrorT2 (vartok,
                       'the parameter to the builtin procedure function {%1Ead} must be a constant or a variable, seen {%2ad}',
@@ -10033,7 +10167,7 @@ END BuildReFunction ;
                         |----------------|
 *)
 
-PROCEDURE BuildImFunction ;
+PROCEDURE BuildImFunction (Sym: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
    func,
    combinedtok,
@@ -10041,6 +10175,7 @@ VAR
    functok    : CARDINAL ;
    NoOfParam  : CARDINAL ;
    ReturnVar,
+   Type,
    Var        : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
@@ -10050,16 +10185,23 @@ BEGIN
    THEN
       Var := OperandT (1) ;
       vartok := OperandTok (1) ;
+      Type := ComplexToScalar (GetDType (Var)) ;
       combinedtok := MakeVirtualTok (functok, functok, vartok) ;
-      IF IsVar(Var) OR IsConst(Var)
+      PopN (NoOfParam+1) ;  (* destroy arguments to this function *)
+      IF ConstExprError (Sym, Var, vartok, ConstExpr)
+      THEN
+         (* Generate fake result.  *)
+         combinedtok := MakeVirtual2Tok (functok, vartok) ;
+         ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
+         PutVar (ReturnVar, Type) ;
+         PushTFtok (ReturnVar, Type, combinedtok)
+      ELSIF IsVar(Var) OR IsConst(Var)
       THEN
          ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (Var))) ;
          PutVar (ReturnVar, ComplexToScalar (GetDType (Var))) ;
          GenQuadO (combinedtok, StandardFunctionOp, ReturnVar, Im, Var, FALSE) ;
-         PopN (NoOfParam+1) ;  (* destroy arguments to this function *)
          PushTFtok (ReturnVar, GetSType (ReturnVar), combinedtok)
       ELSE
-         PopN (NoOfParam+1) ;  (* destroy arguments to this function *)
          PushTFtok (MakeConstLit (combinedtok, MakeKey ('1.0'), RType), RType, combinedtok) ;
          MetaErrorT2 (vartok,
                       'the parameter to the builtin procedure function {%1Ead} must be a constant or a variable, seen {%2ad}',
@@ -10101,34 +10243,53 @@ END BuildImFunction ;
                         |----------------|
 *)
 
-PROCEDURE BuildCmplxFunction ;
+PROCEDURE BuildCmplxFunction (func: CARDINAL; ConstExpr: BOOLEAN) ;
 VAR
+   failure    : BOOLEAN ;
    functok,
-   endtok,
+   rtok, ltok,
    combinedtok: CARDINAL ;
    NoOfParam  : CARDINAL ;
-   func,
+   type,
    ReturnVar,
    l, r       : CARDINAL ;
 BEGIN
    PopT (NoOfParam) ;
    functok := OperandTtok (NoOfParam + 1) ;
-   func := OperandT (NoOfParam + 1) ;
    IF NoOfParam = 2
    THEN
       l := OperandT (2) ;
+      ltok := OperandTtok (2) ;
       r := OperandT (1) ;
-      endtok := OperandTok (1) ;
-      combinedtok := MakeVirtualTok (functok, functok, endtok) ;
-      IF (IsVar(l) OR IsConst(l)) AND
-         (IsVar(r) OR IsConst(r))
+      rtok := OperandTtok (1) ;
+      combinedtok := MakeVirtual2Tok (functok, rtok) ;
+      PopN (NoOfParam+1) ;   (* Destroy arguments to this function.  *)
+      type := GetCmplxReturnType (GetDType (l), GetDType (r)) ;
+      ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (l) AND IsConst (r))) ;
+      PutVar (ReturnVar, type) ;
+      failure := FALSE ;
+      IF ConstExprError (func, l, ltok, ConstExpr)
+      THEN
+         (* ConstExprError has generated an error message we will fall through
+            and check the right operand.  *)
+         failure := TRUE
+      END ;
+      IF ConstExprError (func, r, rtok, ConstExpr)
+      THEN
+         (* Right operand is in error as a variable.  *)
+         failure := TRUE
+      END ;
+      IF failure
+      THEN
+         (* Generate a fake result if either operand was a variable (and we
+            are in a const expression).  *)
+         PushTFtok (ReturnVar, type, combinedtok)
+      ELSIF (IsVar (l) OR IsConst (l)) AND
+         (IsVar (r) OR IsConst (r))
       THEN
          CheckExpressionCompatible (combinedtok, GetSType(l), GetSType(r)) ;
-         ReturnVar := MakeTemporary (combinedtok, AreConstant (IsConst (l) AND IsConst (r))) ;
-         PutVar (ReturnVar, GetCmplxReturnType (GetDType (l), GetDType (r))) ;
          GenQuadO (combinedtok, StandardFunctionOp, ReturnVar, Cmplx, Make2Tuple (l, r), TRUE) ;
-         PopN (NoOfParam+1) ;   (* destroy arguments to this function *)
-         PushTFtok (ReturnVar, GetSType (ReturnVar), combinedtok)
+         PushTFtok (ReturnVar, type, combinedtok)
       ELSE
          IF IsVar (l) OR IsConst (l)
          THEN
@@ -10140,7 +10301,6 @@ BEGIN
                          'the builtin procedure {%1Ead} requires two parameters, both must be variables or constants but the first parameter is {%2d}',
                       func, l)
          END ;
-         PopN (NoOfParam+1) ;  (* destroy arguments to this function *)
          PushTFtok (MakeConstLit (combinedtok, MakeKey ('1.0'), CType), CType, combinedtok)
       END
    ELSE
@@ -11374,7 +11534,7 @@ BEGIN
       PushT (Address) ;
       PushTtok (sym, tokpos) ;
       PushT(2) ;          (* Two parameters *)
-      BuildConvertFunction ;
+      BuildConvertFunction (Convert, FALSE) ;
       PopT (adr) ;
       RETURN adr
    END
@@ -11487,7 +11647,7 @@ BEGIN
          PushT (Cardinal) ;
          PushTtok (idx, indexTok) ;
          PushT(2) ;          (* Two parameters *)
-         BuildConvertFunction ;
+         BuildConvertFunction (Convert, FALSE) ;
          PopT (idx)
       END ;
       PutVar (tj, Cardinal) ;
@@ -11941,7 +12101,6 @@ VAR
    typepos,
    Type   : CARDINAL ;
    NulSet : CARDINAL ;
-   tok    : CARDINAL ;
 BEGIN
    PopTtok (Type, typepos) ;  (* type of set we are building *)
    IF (Type = NulSym) AND Pim
@@ -12244,7 +12403,6 @@ END BuildConstructorStart ;
 
 PROCEDURE BuildConstructorEnd (startpos, cbratokpos: CARDINAL) ;
 VAR
-   typetok,
    value, valtok: CARDINAL ;
 BEGIN
    IF DebugTokPos
@@ -12510,7 +12668,7 @@ BEGIN
       PushT(type) ;
       PushT(sym) ;
       PushT(2) ;          (* Two parameters *)
-      BuildConvertFunction ;
+      BuildConvertFunction (Convert, FALSE) ;
       PopT(sym)
    END ;
    RETURN( sym )
diff --git a/gcc/testsuite/gm2/iso/const/fail/expression.mod b/gcc/testsuite/gm2/iso/const/fail/expression.mod
new file mode 100644
index 0000000..121d7f4
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/expression.mod
@@ -0,0 +1,10 @@
+MODULE expression ;
+
+CONST
+   foo = ABS (i) + 2 + ABS (-100) ;
+
+VAR
+   i: INTEGER ;
+BEGIN
+
+END expression.
diff --git a/gcc/testsuite/gm2/iso/const/fail/iso-const-fail.exp b/gcc/testsuite/gm2/iso/const/fail/iso-const-fail.exp
new file mode 100644
index 0000000..59b6b29
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/iso-const-fail.exp
@@ -0,0 +1,36 @@
+# Copyright (C) 2024 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# This file was written by Gaius Mulley (gaius.mulley@southwales.ac.uk)
+# for GNU Modula-2.
+
+if $tracelevel then {
+    strace $tracelevel
+}
+
+# load support procs
+load_lib gm2-torture.exp
+
+gm2_init_iso "${srcdir}/gm2/iso/const/fail"
+
+foreach testcase [lsort [glob -nocomplain $srcdir/$subdir/*.mod]] {
+    # If we're only testing specific files and this isn't one of them, skip it.
+    if ![runtest_file_p $runtests $testcase] then {
+	continue
+    }
+
+    gm2-torture-fail $testcase
+}
diff --git a/gcc/testsuite/gm2/iso/const/fail/testabs.mod b/gcc/testsuite/gm2/iso/const/fail/testabs.mod
new file mode 100644
index 0000000..561688b
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testabs.mod
@@ -0,0 +1,10 @@
+MODULE testabs ;
+
+CONST
+   foo = ABS (i + 1) ;
+
+VAR
+   i: INTEGER ;
+BEGIN
+
+END testabs.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testaddadr.mod b/gcc/testsuite/gm2/iso/const/fail/testaddadr.mod
new file mode 100644
index 0000000..a9ebe8a
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testaddadr.mod
@@ -0,0 +1,12 @@
+MODULE testaddadr ;
+
+IMPORT SYSTEM ;
+
+CONST
+   foo = SYSTEM.ADDADR (ADR (a) + ADR (b)) ;
+
+VAR
+   a, b: CARDINAL ;
+BEGIN
+
+END testaddadr.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testcap.mod b/gcc/testsuite/gm2/iso/const/fail/testcap.mod
new file mode 100644
index 0000000..e6d983d
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testcap.mod
@@ -0,0 +1,10 @@
+MODULE testcap ;
+
+CONST
+   foo = CAP (ch) ;
+
+VAR
+   ch: CHAR ;
+BEGIN
+
+END testcap.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testcap2.mod b/gcc/testsuite/gm2/iso/const/fail/testcap2.mod
new file mode 100644
index 0000000..239472b
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testcap2.mod
@@ -0,0 +1,10 @@
+MODULE testcap2 ;
+
+CONST
+   foo = CAP (ch + '8' - '1') ;
+
+VAR
+   ch: CHAR ;
+BEGIN
+
+END testcap2.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testchr.mod b/gcc/testsuite/gm2/iso/const/fail/testchr.mod
new file mode 100644
index 0000000..cf3b5b8
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testchr.mod
@@ -0,0 +1,10 @@
+MODULE testchr ;
+
+CONST
+   foo = ORD (CHR (c)) ;
+
+VAR
+   c: CARDINAL ;
+BEGIN
+
+END testchr.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testchr2.mod b/gcc/testsuite/gm2/iso/const/fail/testchr2.mod
new file mode 100644
index 0000000..73e2d23
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testchr2.mod
@@ -0,0 +1,10 @@
+MODULE testchr2 ;
+
+CONST
+   foo = CHR (c) ;
+
+VAR
+   c: CARDINAL ;
+BEGIN
+
+END testchr2.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testcmplx.mod b/gcc/testsuite/gm2/iso/const/fail/testcmplx.mod
new file mode 100644
index 0000000..e9e22c0
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testcmplx.mod
@@ -0,0 +1,10 @@
+MODULE testcmplx ;
+
+CONST
+   foo = CMPLX (r, i) ;
+
+VAR
+   r, i: REAL ;
+BEGIN
+
+END testcmplx.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testfloat.mod b/gcc/testsuite/gm2/iso/const/fail/testfloat.mod
new file mode 100644
index 0000000..371e7fb
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testfloat.mod
@@ -0,0 +1,10 @@
+MODULE testfloat ;
+
+CONST
+   foo = FLOAT (c) ;
+
+VAR
+   c: CARDINAL ;
+BEGIN
+
+END testfloat.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testim.mod b/gcc/testsuite/gm2/iso/const/fail/testim.mod
new file mode 100644
index 0000000..02cc2e4
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testim.mod
@@ -0,0 +1,10 @@
+MODULE testim ;
+
+CONST
+   foo = IM (cmplx) ;
+
+VAR
+   cmplx: COMPLEX ;
+BEGIN
+
+END testim.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testint.mod b/gcc/testsuite/gm2/iso/const/fail/testint.mod
new file mode 100644
index 0000000..d241a13
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testint.mod
@@ -0,0 +1,10 @@
+MODULE testint ;
+
+CONST
+   foo = INT (r) ;
+
+VAR
+   r: REAL ;
+BEGIN
+
+END testint.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testlength.mod b/gcc/testsuite/gm2/iso/const/fail/testlength.mod
new file mode 100644
index 0000000..c3f126b
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testlength.mod
@@ -0,0 +1,11 @@
+MODULE testlength ;
+
+PROCEDURE bar (a: ARRAY OF CHAR) ;
+CONST
+   foo = LENGTH (a) ;
+BEGIN
+END bar ;
+
+BEGIN
+   bar ("hello")
+END testlength.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testodd.mod b/gcc/testsuite/gm2/iso/const/fail/testodd.mod
new file mode 100644
index 0000000..d293e0c
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testodd.mod
@@ -0,0 +1,10 @@
+MODULE testodd ;
+
+CONST
+   foo = ODD (x) ;
+
+VAR
+   x: CARDINAL ;
+BEGIN
+
+END testodd.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testord.mod b/gcc/testsuite/gm2/iso/const/fail/testord.mod
new file mode 100644
index 0000000..d862da1
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testord.mod
@@ -0,0 +1,10 @@
+MODULE testord ;
+
+CONST
+   foo = ORD (ch) ;
+
+VAR
+   ch: CHAR ;
+BEGIN
+
+END testord.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testre.mod b/gcc/testsuite/gm2/iso/const/fail/testre.mod
new file mode 100644
index 0000000..60ecde5
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testre.mod
@@ -0,0 +1,10 @@
+MODULE testre ;
+
+CONST
+   foo = RE (cmplx) ;
+
+VAR
+   cmplx: COMPLEX ;
+BEGIN
+
+END testre.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testtrunc.mod b/gcc/testsuite/gm2/iso/const/fail/testtrunc.mod
new file mode 100644
index 0000000..6dcde30
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testtrunc.mod
@@ -0,0 +1,10 @@
+MODULE testtrunc ;
+
+CONST
+   foo = TRUNC (r) ;
+
+VAR
+   r: REAL ;
+BEGIN
+
+END testtrunc.
diff --git a/gcc/testsuite/gm2/iso/const/fail/testval.mod b/gcc/testsuite/gm2/iso/const/fail/testval.mod
new file mode 100644
index 0000000..438955c
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/fail/testval.mod
@@ -0,0 +1,10 @@
+MODULE testval ;
+
+CONST
+   foo = VAL (INTEGER, c) ;
+
+VAR
+   c: CARDINAL ;
+BEGIN
+
+END testval.
diff --git a/gcc/testsuite/gm2/iso/const/pass/constbool.mod b/gcc/testsuite/gm2/iso/const/pass/constbool.mod
new file mode 100644
index 0000000..1be96cc
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/pass/constbool.mod
@@ -0,0 +1,14 @@
+MODULE constbool ;
+
+
+CONST
+   AddressableBits = 32 ;
+   MaxBits         = 32 ;
+
+   BitsInUse =
+    ORD(AddressableBits > MaxBits) * MaxBits +
+    ORD(AddressableBits <= MaxBits) * AddressableBits;
+
+BEGIN
+
+END constbool.
diff --git a/gcc/testsuite/gm2/iso/const/pass/constbool2.mod b/gcc/testsuite/gm2/iso/const/pass/constbool2.mod
new file mode 100644
index 0000000..f8e294b
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/pass/constbool2.mod
@@ -0,0 +1,12 @@
+MODULE constbool2 ;
+
+
+CONST
+   AddressableBits = 32 ;
+   MaxBits         = 32 ;
+
+   BitsInUse = ORD(AddressableBits > MaxBits) * MaxBits + ORD(AddressableBits <= MaxBits) * AddressableBits;
+
+BEGIN
+
+END constbool2.
diff --git a/gcc/testsuite/gm2/iso/const/pass/constbool3.mod b/gcc/testsuite/gm2/iso/const/pass/constbool3.mod
new file mode 100644
index 0000000..e63ffc4
--- /dev/null
+++ b/gcc/testsuite/gm2/iso/const/pass/constbool3.mod
@@ -0,0 +1,12 @@
+MODULE constbool3 ;
+
+
+CONST
+   AddressableBits = 32 ;
+   MaxBits         = 16 ;
+
+   BitsInUse = ORD(AddressableBits > MaxBits) * MaxBits + ORD(AddressableBits <= MaxBits) * AddressableBits;
+
+BEGIN
+
+END constbool3.