refactor(strings): construct string values implicitly from raw literals

Keep double-quoted literals and text constants as C_STRING values. Use
marked STRING constructors for text and CHAR conversion, preserving
string operations and I/O through the existing class machinery.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/tests/iii/implicit-string-opt-in/case.json b/tests/iii/implicit-string-opt-in/case.json
new file mode 100644
index 0000000..8fae19d
--- /dev/null
+++ b/tests/iii/implicit-string-opt-in/case.json
@@ -0,0 +1,15 @@
+{
+  "compiler_args": [
+    "-no-std"
+  ],
+  "errors": [
+    {
+      "line": 13,
+      "reason": "Cannot implicitly convert C_STRING to STRING"
+    },
+    {
+      "line": 14,
+      "reason": "STRING requires an IMPLICIT constructor NEW"
+    }
+  ]
+}