From 6bbac2edf7c50dac4d755a364b6dfd16471284d7 Mon Sep 17 00:00:00 2001
From: zinc <zinc@downsta.ir>
Date: Thu, 15 Oct 2026 09:56:19 +0330
Subject: analyzer: check borrow returns of forward-called functions at the
 unit's end; borrows clause for prototypes, definitions, externs and function
 types, checked against the body

---
 tests/errors/borrows_body.zc          | 13 +++++++++++++
 tests/errors/borrows_decl.zc          | 14 ++++++++++++++
 tests/errors/borrows_extern.zc        | 11 +++++++++++
 tests/errors/borrows_fntype.zc        | 12 ++++++++++++
 tests/errors/forward_borrow_return.zc | 11 +++++++++++
 5 files changed, 61 insertions(+)
 create mode 100644 tests/errors/borrows_body.zc
 create mode 100644 tests/errors/borrows_decl.zc
 create mode 100644 tests/errors/borrows_extern.zc
 create mode 100644 tests/errors/borrows_fntype.zc
 create mode 100644 tests/errors/forward_borrow_return.zc

(limited to 'tests/errors')

diff --git a/tests/errors/borrows_body.zc b/tests/errors/borrows_body.zc
new file mode 100644
index 0000000..e6c92c6
--- /dev/null
+++ b/tests/errors/borrows_body.zc
@@ -0,0 +1,13 @@
+namespace;
+include rt;
+
+// expect: first: returns a borrow of b, but its borrows clause doesn't name it
+// the body is checked against the prototype's borrows clause.
+char* first(char* a, char* b) borrows a;
+fn main() {
+	char* t = rt.new(4); t[0] = 'x'; t[1] = 0;
+	char* u = rt.new(4); u[0] = 'y'; u[1] = 0;
+	let r = first(t, u); rt.put_c(r[0]); rt.free(u); rt.free(t);
+	return 0;
+}
+char* first(char* a, char* b) { return b; }
diff --git a/tests/errors/borrows_decl.zc b/tests/errors/borrows_decl.zc
new file mode 100644
index 0000000..5229979
--- /dev/null
+++ b/tests/errors/borrows_decl.zc
@@ -0,0 +1,14 @@
+namespace;
+include rt;
+
+// expect: r: used after it was given away; r borrows t, and t was freed on line 11 (t declared on line 8)
+// a prototype's borrows clause ties the result to the first argument's owner only.
+char* first(char* a, char* b) borrows a;
+fn main() {
+	char* t = rt.new(4); t[0] = 'x'; t[1] = 0;
+	char* u = rt.new(4); u[0] = 'y'; u[1] = 0;
+	let r = first(t, u); rt.free(u); rt.put_c(r[0]);
+	rt.free(t); rt.put_c(r[0]);
+	return 0;
+}
+char* first(char* a, char* b) { return a; }
diff --git a/tests/errors/borrows_extern.zc b/tests/errors/borrows_extern.zc
new file mode 100644
index 0000000..e9285d4
--- /dev/null
+++ b/tests/errors/borrows_extern.zc
@@ -0,0 +1,11 @@
+namespace;
+include rt;
+
+// expect: r: used after it was given away; r borrows t, and t was freed on line 9 (t declared on line 8)
+// an extern declares its borrow return by parameter position.
+extern char* strchr(char*, int) borrows 0;
+fn main() {
+	char* t = rt.new(4); t[0] = 'x'; t[1] = 0;
+	let r = strchr(t, 'x'); rt.free(t); rt.put_c(r[0]);
+	return 0;
+}
diff --git a/tests/errors/borrows_fntype.zc b/tests/errors/borrows_fntype.zc
new file mode 100644
index 0000000..a73b0d8
--- /dev/null
+++ b/tests/errors/borrows_fntype.zc
@@ -0,0 +1,12 @@
+namespace;
+include rt;
+
+// expect: r: used after it was given away; r borrows t, and t was freed on line 10 (t declared on line 9)
+// a function type carries a borrows clause, by parameter position.
+char* skip(char* s) { return s + 1; }
+fn main() {
+	char*(char*) borrows 0 f = skip;
+	char* t = rt.new(4); t[0] = 'x'; t[1] = 'y'; t[2] = 0;
+	let r = f(t); rt.free(t); rt.put_c(r[0]);
+	return 0;
+}
diff --git a/tests/errors/forward_borrow_return.zc b/tests/errors/forward_borrow_return.zc
new file mode 100644
index 0000000..6c3ae93
--- /dev/null
+++ b/tests/errors/forward_borrow_return.zc
@@ -0,0 +1,11 @@
+namespace;
+include rt;
+
+// expect: r: used after it was given away; r borrows t, and t was freed on line 8 (t declared on line 7); skip, defined after this call, returns a borrow of its argument
+// skip is called before its body: its borrow return is checked when the body is read.
+fn main() {
+	char* t = rt.new(8); t[0] = ' '; t[1] = 'a'; t[2] = 0;
+	let r = skip(t); rt.free(t); rt.put_c(r[0]);
+	return 0;
+}
+char* skip(char* s) { int i = 0; while (s[i] == ' ') i++; return s + i; }
-- 
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