add c-style typedef and a built-in string alias

typedef T name; binds name to the type record of T, at the top level or
in a function (scoped to its block). string is a built-in alias for char*.
A type name straight before , or ) in a parameter list is the parameter's
name, so fn f(string) still works. The language server shows typedef T
name; on hover and highlights typedef as a keyword.

2 files changed, 13 insertions, 0 deletions

diff --git a/tests/typeerrors/typedef_mismatch.zc b/tests/typeerrors/typedef_mismatch.zc
new file mode 100644
index 0000000..26453dd
--- /dev/null
+++ b/tests/typeerrors/typedef_mismatch.zc
@@ -0,0 +1,6 @@
+namespace;
+
+// expect: type error: initializer: expected int, got char*
+typecheck on;
+typedef int count;
+fn main() { count c = "text"; return 0; }
diff --git a/tests/typeerrors/typedef_pointer.zc b/tests/typeerrors/typedef_pointer.zc
new file mode 100644
index 0000000..5dbbb17
--- /dev/null
+++ b/tests/typeerrors/typedef_pointer.zc
@@ -0,0 +1,7 @@
+namespace;
+
+// expect: type error: initializer: expected node*, got int*
+typecheck on;
+struct node { int v; };
+typedef node* link;
+fn main() { int n = 0; link p = &n; return 0; }