scc

commit 4ed4dac59ff781ba4bd54db585c2384595e175dc
parent eb28f98e61cf995a7c1f9c85faf3431438018e03
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(-)
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)
 {