From 692ebaba85c4d76a28534e4004b369cc156548a3 Mon Sep 17 00:00:00 2001
From: Stephen Heumann <stephenheumann@gmail.com>
Date: Sun, 17 Oct 2021 22:22:42 -0500
Subject: [PATCH] Structs or arrays may not contain structs with a flexible
 array member.

We previously ignored this, but it is a constraint violation under the C standards, so it should be reported as an error.

GCC and Clang allow this as an extension, as we were effectively doing previously. We will follow the standards for now, but if there was demand for such an extension in ORCA/C, it could be re-introduced subject to a #pragma ignore flag.
---
 CCommon.pas |  1 +
 Header.pas  |  4 +++-
 Parser.pas  | 21 +++++++++++++++++----
 Scanner.pas |  1 +
 Symbol.pas  |  2 ++
 5 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/CCommon.pas b/CCommon.pas
index 7666d35..07aed11 100644
--- a/CCommon.pas
+++ b/CCommon.pas
@@ -310,6 +310,7 @@ type
         unionType   : (fieldList: identPtr;	{field list}
 		       sName: stringPtr;	{struct name; for forward refs}
 		       constMember: boolean;    {does it have a const member?}
+		       flexibleArrayMember: boolean; {does it have a FAM?}
                       );
      end;
 
diff --git a/Header.pas b/Header.pas
index d93d0b4..38637c7 100644
--- a/Header.pas
+++ b/Header.pas
@@ -18,7 +18,7 @@ uses CCommon, MM, Scanner, Symbol, CGI;
 {$segment 'SCANNER'}
 
 const
-   symFileVersion = 17;                 {version number of .sym file format}
+   symFileVersion = 18;                 {version number of .sym file format}
 
 var
    inhibitHeader: boolean;		{should .sym includes be blocked?}
@@ -1063,6 +1063,7 @@ procedure EndInclude {chPtr: ptr};
                 	end; {while}
         	     WriteByte(0);
         	     WriteByte(ord(tp^.constMember));
+        	     WriteByte(ord(tp^.flexibleArrayMember));
         	     end;
 
 		  otherwise: ;
@@ -1700,6 +1701,7 @@ var
         		ep := ip;
         		end; {while}
         	     tp^.constMember := boolean(ReadByte);
+        	     tp^.flexibleArrayMember := boolean(ReadByte);
         	     end;
 
         	  enumType: ;
diff --git a/Parser.pas b/Parser.pas
index dc40054..0377ed3 100644
--- a/Parser.pas
+++ b/Parser.pas
@@ -2847,8 +2847,10 @@ var
                   maxDisp := disp;
                if variable^.itype^.size = 0 then
                   if (variable^.itype^.kind = arrayType) 
-                     and (disp > 0) then {handle flexible array member}
-                     didFlexibleArray := true
+                     and (disp > 0) then begin {handle flexible array member}
+                     didFlexibleArray := true;
+                     tp^.flexibleArrayMember := true;
+                     end {if}
                   else
                      Error(117);
                end {if}
@@ -2868,10 +2870,16 @@ var
                   tPtr := tPtr^.aType;
                end; {while}
             if tqConst in tPtr^.qualifiers then
-               tp^.constMember := true
-            else if tPtr^.kind in [structType,unionType] then
+               tp^.constMember := true;
+            if tPtr^.kind in [structType,unionType] then begin
                if tPtr^.constMember then
                   tp^.constMember := true;
+               if tPtr^.flexibleArrayMember then
+                  if kind = structType then
+                     Error(169)
+                  else {if kind = unionType then}
+                     tp^.flexibleArrayMember := true;
+               end; {if}
 
             if token.kind = commach then {allow repeated declarations}
                begin
@@ -3220,6 +3228,7 @@ while token.kind in allowedTokens do begin
                  {structTypePtr^.fieldList := nil;}
                  {structTypePtr^.sName := nil;}
                  {structTypePtr^.constMember := false;}
+                 {structTypePtr^.flexibleArrayMember := false;}
                   structPtr := NewSymbol(ttoken.name, structTypePtr, ident,
                      tagSpace, defined);
                   structTypePtr^.sName := structPtr^.name;
@@ -3253,6 +3262,7 @@ while token.kind in allowedTokens do begin
               {structTypePtr^.fieldList := nil;}
               {structTypePtr^.sName := nil;}
               {structTypePtr^.constMember := false;}
+              {structTypePtr^.flexibleArrayMember := false;}
                end; {if}
             if structPtr <> nil then
                structPtr^.itype := structTypePtr;
@@ -3389,6 +3399,9 @@ var
                Error(123);
                goto 1;
                end; {if}
+            if tp^.aType^.kind in [structType,unionType] then
+               if tp^.aType^.flexibleArrayMember then
+                  Error(169);
             end; {if}
          firstVariable := false;        {unspecified sizes are only allowed in }
                                         { the first subscript                  }
diff --git a/Scanner.pas b/Scanner.pas
index 8a0573a..d59c02a 100644
--- a/Scanner.pas
+++ b/Scanner.pas
@@ -740,6 +740,7 @@ if list or (numErr <> 0) then begin
         166: msg := @'string literals with these prefixes may not be merged';
         167: msg := @'''L''-prefixed character or string constants are not supported by ORCA/C';
         168: msg := @'malformed hexadecimal floating constant';
+        169: msg := @'struct or array may not contain a struct with a flexible array member';
          otherwise: Error(57);
          end; {case}
        writeln(msg^);
diff --git a/Symbol.pas b/Symbol.pas
index 228905b..7578a64 100644
--- a/Symbol.pas
+++ b/Symbol.pas
@@ -1612,6 +1612,8 @@ with defaultStruct^ do begin            {(for structures with errors)}
    qualifiers := [];
    kind := structType;
    sName := nil;
+   constMember := false;
+   flexibleArrayMember := false;
    new(fieldList);
    with fieldlist^ do begin
       next := nil;