From 2408c9602c89f974a9b91dbd171b8cc133068c19 Mon Sep 17 00:00:00 2001
From: Stephen Heumann <stephenheumann@gmail.com>
Date: Thu, 4 Feb 2021 12:44:44 -0600
Subject: [PATCH] Make expressionValue a saturating approximation of the true
 value for long long expressions.

This gives sensible behavior for several things in the parser, e.g. where all negative values or all very large values should be disallowed.
---
 CCommon.pas    |  2 +-
 Expression.pas | 17 +++++++++++++++--
 Parser.pas     |  6 +++---
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/CCommon.pas b/CCommon.pas
index cad3a88..0c060da 100644
--- a/CCommon.pas
+++ b/CCommon.pas
@@ -491,7 +491,7 @@ var
                                         {------------------}
    doDispose: boolean;                  {dispose of the expression tree as we go?}
    realExpressionValue: double;         {value of the last real constant expression}
-   longlongExpressionValue: longlong;   {value of the last long long constant expression}
+   llExpressionValue: longlong;         {value of the last long long constant expression}
    expressionValue: longint;            {value of the last constant expression}
    expressionType: typePtr;             {the type of the expression}
    initializerTree: tokenPtr;           {for non-constant initializers}
diff --git a/Expression.pas b/Expression.pas
index b914088..9a801d0 100644
--- a/Expression.pas
+++ b/Expression.pas
@@ -3899,6 +3899,8 @@ if kind = normalExpression then begin   {generate code from the expression tree}
 else begin                              {record the expression for an initializer}
    initializerTree := tree;
    isConstant := false;
+   llExpressionValue.lo := 0;
+   llExpressionValue.hi := 0;
    if errorFound then begin
       DisposeTree(initializerTree);
       initializerTree := nil;
@@ -3955,12 +3957,23 @@ else begin                              {record the expression for an initialize
          isConstant := true;
          end {else if}
       else if tree^.token.kind = longlongconst then begin
-         longlongExpressionValue := tree^.token.qval;
+         llExpressionValue := tree^.token.qval;
+         if ((llExpressionValue.hi = 0) and (llExpressionValue.lo >= 0))
+            or ((llExpressionValue.hi = -1) and (llExpressionValue.lo < 0)) then
+            expressionValue := llExpressionValue.lo
+         else if llExpressionValue.hi < 0 then
+            expressionValue := $80000000
+         else
+            expressionValue := $7fffffff;
          expressionType := longLongPtr;
          isConstant := true;
          end {else if}
       else if tree^.token.kind = ulonglongconst then begin
-         longlongExpressionValue := tree^.token.qval;
+         llExpressionValue := tree^.token.qval;
+         if llExpressionValue.hi = 0 then
+            expressionValue := llExpressionValue.lo
+         else
+            expressionValue := $FFFFFFFF;
          expressionType := ulongLongPtr;
          isConstant := true;
          end {else if}
diff --git a/Parser.pas b/Parser.pas
index 4c2e0c5..1addc76 100644
--- a/Parser.pas
+++ b/Parser.pas
@@ -1947,7 +1947,7 @@ var
    if isConstant and (variable^.storage in [external,global,private]) then begin
       if bitsize = 0 then begin
          if etype^.baseType in [cgQuad,cgUQuad] then begin
-            iPtr^.qVal := longlongExpressionValue;
+            iPtr^.qVal := llExpressionValue;
             end {if}
          else begin
             iPtr^.qval.hi := 0;
@@ -2031,8 +2031,8 @@ var
                      errorFound := true;
                      end {else}
                else if etype^.baseType in [cgQuad,cgUQuad] then
-                  if (longlongExpressionValue.hi = 0) and
-                     (longlongExpressionValue.lo = 0) then
+                  if (llExpressionValue.hi = 0) and
+                     (llExpressionValue.lo = 0) then
                      iPtr^.iType := cgULong
                   else begin
                      Error(47);