From 3c4cea0b5abc137df4b26ef443f24186cf9cb3f5 Mon Sep 17 00:00:00 2001
From: NeilBrown <neil@brown.name>
Date: Thu, 14 Oct 2021 13:43:02 +1100
Subject: [PATCH] oceani: handle variable-sized arrays better.

An array with size set by a constant variable(!) might have a different
size each time the declaration is encountered.  So we need to
re-evaluate the size each time.
We currently re-evaluate the size only if it is zero.

So for numerical-constant sized arrays, evaluate size during parsing.
For other arrays, re-evaulate each time using a new prepare_type method.

Signed-off-by: NeilBrown <neil@brown.name>
---
 csrc/oceani-tests.mdc |  2 +-
 csrc/oceani.mdc       | 49 +++++++++++++++++++++++++------------------
 2 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/csrc/oceani-tests.mdc b/csrc/oceani-tests.mdc
index 90bfc19..46c1a09 100644
--- a/csrc/oceani-tests.mdc
+++ b/csrc/oceani-tests.mdc
@@ -533,7 +533,7 @@ ad-hoc things array related.
 
 		for i:=0; then i=i+1; while i<5:
 			j ::= i
-			ra:[5]number
+			ra:[j]number
 			ra[i-1] = i*i
 			ra[6] = 42 // mustn't crash
 			print '', bools[i], ra[j-1],
diff --git a/csrc/oceani.mdc b/csrc/oceani.mdc
index 2804224..7ff26c5 100644
--- a/csrc/oceani.mdc
+++ b/csrc/oceani.mdc
@@ -429,6 +429,7 @@ Named type are stored in a simple linked list.  Objects of each type are
 		struct type *next;
 		int size, align;
 		void (*init)(struct type *type, struct value *val);
+		void (*prepare_type)(struct type *type);
 		void (*print)(struct type *type, struct value *val);
 		void (*print_type)(struct type *type, FILE *f);
 		int (*cmp_order)(struct type *t1, struct type *t2,
@@ -536,8 +537,6 @@ Named type are stored in a simple linked list.  Objects of each type are
 	{
 		struct value *ret;
 
-		if (!t->size)
-			val_init(t, NULL);
 		ret = calloc(1, t->size);
 		if (init)
 			memcpy(ret, init, t->size);
@@ -1511,20 +1510,25 @@ make a copy of an array with controllable recursive depth.
 
 ###### value functions
 
-	static void array_init(struct type *type, struct value *val)
+	static void array_prepare_type(struct type *type)
 	{
-		int i;
+		mpz_t q;
+		if (!type->array.vsize)
+			return;
+
+		mpz_init(q);
+		mpz_tdiv_q(q, mpq_numref(type->array.vsize->val->num),
+		           mpq_denref(type->array.vsize->val->num));
+		type->array.size = mpz_get_si(q);
+		mpz_clear(q);
 
-		if (type->array.vsize) {
-			mpz_t q;
-			mpz_init(q);
-			mpz_tdiv_q(q, mpq_numref(type->array.vsize->val->num),
-			           mpq_denref(type->array.vsize->val->num));
-			type->array.size = mpz_get_si(q);
-			mpz_clear(q);
-		}
 		type->size = type->array.size * type->array.member->size;
 		type->align = type->array.member->align;
+	}
+
+	static void array_init(struct type *type, struct value *val)
+	{
+		int i;
 
 		if (!val)
 			return;		
@@ -1572,6 +1576,7 @@ make a copy of an array with controllable recursive depth.
 
 	static struct type array_prototype = {
 		.init = array_init,
+		.prepare_type = array_prepare_type,
 		.print_type = array_print_type,
 		.compat = array_compat,
 		.free = array_free,
@@ -1586,16 +1591,17 @@ make a copy of an array with controllable recursive depth.
 		char tail[3];
 		mpq_t num;
 		struct text noname = { "", 0 };
+		struct type *t;
 
-		$0 = add_type(c, noname, &array_prototype);
-		$0->array.member = $<4;
-		$0->array.vsize = NULL;
+		$0 = t = add_type(c, noname, &array_prototype);
+		t->array.member = $<4;
+		t->array.vsize = NULL;
 		if (number_parse(num, tail, $2.txt) == 0)
 			tok_err(c, "error: unrecognised number", &$2);
 		else if (tail[0])
 			tok_err(c, "error: unsupported number suffix", &$2);
 		else {
-			$0->array.size = mpz_get_ui(mpq_numref(num));
+			t->array.size = mpz_get_ui(mpq_numref(num));
 			if (mpz_cmp_ui(mpq_denref(num), 1) != 0) {
 				tok_err(c, "error: array size must be an integer",
 				        &$2);
@@ -1604,6 +1610,8 @@ make a copy of an array with controllable recursive depth.
 				        &$2);
 			mpq_clear(num);
 		}
+		t->size = t->array.size * t->array.member->size;
+		t->align = t->array.member->align;
 	} }$
 
 	| [ IDENTIFIER ] Type ${ {
@@ -3356,15 +3364,16 @@ it is declared, and error will be raised as the name is created as
 		struct variable *v = cast(var, b->left)->var;
 		if (v->merged)
 			v = v->merged;
+		free_value(v->type, v->val);
+		free(v->val);
+		if (v->type->prepare_type)
+			// FIXME is this the first usage of the type?
+			v->type->prepare_type(v->type);
 		if (b->right) {
 			right = interp_exec(b->right, &rtype);
-			free_value(v->type, v->val);
-			free(v->val);
 			v->val = val_alloc(v->type, &right);
 			rtype = Tnone;
 		} else {
-			free_value(v->type, v->val);
-			free(v->val);
 			v->val = val_alloc(v->type, NULL);
 		}
 		break;
-- 
2.43.0