From 7c4217eaaf28ebf52106a4b2e8b03e992fef5da0 Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Sun, 24 Mar 2024 01:13:15 -0700
Subject: attr: Parse some GNU attributes

Implements: https://todo.sr.ht/~mcf/cproc/68
---
 attr.c | 23 +++++++++++++++++++++++
 cc.h   |  6 +++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/attr.c b/attr.c
index 8b06d46..31d16f7 100644
--- a/attr.c
+++ b/attr.c
@@ -1,3 +1,4 @@
+#include <limits.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <string.h>
@@ -48,6 +49,28 @@ parseattr(struct attr *a, enum attrkind allowed, enum attrprefix prefix)
 	switch (prefix) {
 	case PREFIXGNU:
 		prefixname = "GNU ";
+		if (strcmp(name, "aligned") == 0) {
+			kind = ATTRALIGNED;
+			if (consume(TLPAREN)) {
+				unsigned long long i;
+
+				i = intconstexpr(&filescope, false);
+				if (!i || i & i - 1 || i > INT_MAX)
+					error(&tok.loc, "invalid alignment %llu", i);
+				if (a)
+					a->align = i;
+				expect(TRPAREN, "after alignment");
+			} else {
+				if (a)
+					a->align = 16;
+			}
+		} else if (strcmp(name, "constructor") == 0) {
+			kind = ATTRCONSTRUCTOR;
+		} else if (strcmp(name, "destructor") == 0) {
+			kind = ATTRDESTRUCTOR;
+		} else if (strcmp(name, "packed") == 0) {
+			kind = ATTRPACKED;
+		}
 		break;
 	}
 	if (kind) {
diff --git a/cc.h b/cc.h
index e07273f..974e1ef 100644
--- a/cc.h
+++ b/cc.h
@@ -473,11 +473,15 @@ void targinit(const char *);
 /* attr */
 
 enum attrkind {
-	ATTRNONE,
+	ATTRALIGNED     = 1<<0,
+	ATTRCONSTRUCTOR = 1<<1,
+	ATTRDESTRUCTOR  = 1<<2,
+	ATTRPACKED      = 1<<3,
 };
 
 struct attr {
 	enum attrkind kind;
+	int align;
 };
 
 _Bool attr(struct attr *, enum attrkind);
-- 
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