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       cc1: Fix sizeof expressions - scc - simple c99 compiler
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       ---
   DIR commit 4ed4dac59ff781ba4bd54db585c2384595e175dc
   DIR parent eb28f98e61cf995a7c1f9c85faf3431438018e03
  HTML Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
       Date:   Tue,  8 Oct 2024 12:51:19 +0200
       
       cc1: Fix sizeof expressions
       
       The commit c863f707 tried to fix expressions like:
       
               sizeof((int) 1)
       
       and changed the reduction in sizeexp() from unary to cast,
       but it had the side effect of allowing things like
       
               sizeof (int) 1
       
       that is invalid, and having problems with things like
       
               sizeof "hello" - 1
       
       The commit 4a0c2ccd tried to fix this last case reverting c863f707
       that moved the code to the original point. The problem is that
       to avoid the ambiguity when a '(' follows a sizeof (because
       it can be a typename or an expression) then the rule chain
       
               unary
                       -> SIZEOF unary
                       -> SIZEOF postfix
                       -> SIZEOF primary
                       -> SIZEOF ( expr )
       
       was collapsed to
       
               unary
                       -> SIZEOF ( unary )
       
       because when a ( happend after a SIZEOF token then the next token
       was looked to see if it was a typename or not to decide to apply
       the chain:
       
               unary
                       -> SIZEOF ( typename )
       
       And it can be seen the problem is that the collapsing was wrong
       because we should have SIZEOF ( expr ) instead of SIZEOF ( unary ),
       but still SIZEOF unary when no ( follows the SIZEOF token.
       
       Diffstat:
         M src/cmd/cc/cc1/expr.c               |       6 ++++--
       
       1 file changed, 4 insertions(+), 2 deletions(-)
       ---
   DIR diff --git a/src/cmd/cc/cc1/expr.c b/src/cmd/cc/cc1/expr.c
       @@ -843,7 +843,7 @@ typeof(Node *np)
                return tp;
        }
        
       -static Node *unary(void), *cast(void);
       +static Node *unary(void);
        
        static Type *
        sizeexp(void)
       @@ -859,7 +859,7 @@ sizeexp(void)
                        tp = typename();
                        break;
                default:
       -                tp = typeof(unary());
       +                tp = typeof(expr());
                        break;
                }
                expect(')');
       @@ -903,6 +903,8 @@ postfix(Node *lp)
                }
        }
        
       +static Node *cast(void);
       +
        static Node *
        unary(void)
        {