Improve error messages on expressions like var $type = int; #1553.

releasenotes.md

@@ -13,6 +13,7 @@
 - Infer now works across ternary.
 - Interfaces now support .ptr and .type directly without casting to `any`.
 - Switch to `<* *>` docs.
+- Improve error messages on expressions like `var $type = int;` #1553.
 
 ### Fixes
 - `Unsupported int[*] $x = { 1, 2, 3, 4 }` #1489.
@@ -35,6 +36,7 @@
 - Standard library is now correctly weakly linked, fixing the use of C3 .so together with executable. #1549, #1107.
 - Wrong error message for interface methods with body #1536.
 - Empty expression block would crash compiler with debug on #1554.
+
 ### Stdlib changes
 - Remove unintended print of `char[]` as String
 - Add read/write to stream with big endian ints.

src/compiler/sema_decls.c

@@ -3746,6 +3746,11 @@ bool sema_analyse_var_decl_ct(SemaContext *context, Decl *decl)
 			// If we don't have a type, resolve the expression.
 			if ((init = decl->var.init_expr))
 			{
+				if (init->expr_kind == EXPR_TYPEINFO)
+				{
+					SEMA_ERROR(init, "You can't assign a type to a regular compile time variable like '%s', but it would be allowed if the variable was a compile time type variable. Such a variable needs to have a type-like name, e.g. '$MyType'.", decl->name);
+					goto FAIL;
+				}
 				if (!sema_analyse_expr(context, init)) goto FAIL;
 				// Check it is constant.
 				if (!expr_is_runtime_const(init))