From 8c2c9f6e2183c0617bc4a29de88f59077f6ac9c2 Mon Sep 17 00:00:00 2001
From: Engin Kayraklioglu <e-kayrakli@users.noreply.github.com>
Date: Tue, 4 Feb 2025 16:31:20 -0800
Subject: [PATCH] Workaround an issue preventing users to catch errors from

Signed-off-by: Engin Kayraklioglu <e-kayrakli@users.noreply.github.com>
---
 modules/standard/JSON.chpl                    |  7 ++++++-
 .../jsonHelpers/fromJsonThrows.chpl           | 20 +++++++++++++++++++
 .../jsonHelpers/fromJsonThrows.cleanfiles     |  1 +
 .../jsonHelpers/fromJsonThrows.good           |  1 +
 .../jsonHelpers/fromJsonThrows.preexec        |  3 +++
 5 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 test/io/serializers/jsonHelpers/fromJsonThrows.chpl
 create mode 100644 test/io/serializers/jsonHelpers/fromJsonThrows.cleanfiles
 create mode 100644 test/io/serializers/jsonHelpers/fromJsonThrows.good
 create mode 100755 test/io/serializers/jsonHelpers/fromJsonThrows.preexec

diff --git a/modules/standard/JSON.chpl b/modules/standard/JSON.chpl
index 9e2a1d1c3ea3..7d2705939308 100644
--- a/modules/standard/JSON.chpl
+++ b/modules/standard/JSON.chpl
@@ -1185,7 +1185,12 @@ module JSON {
   proc fromJson(jsonString: string, type loadAs): loadAs throws {
     var fileReader = openStringReader(jsonString,
                                       deserializer=new jsonDeserializer());
-    return fileReader.read(loadAs);
+    // we want `return fileReader.read(loadAs)`. But that ends up using a
+    // non-throwing compiler-generated initializer. That prevents the user to
+    // catch errors that are due to malformed jsonString.
+    var ret: loadAs;
+    fileReader.read(ret);
+    return ret;
   }
 
   /* Given a Chapel value, serialize it into a JSON string using the
diff --git a/test/io/serializers/jsonHelpers/fromJsonThrows.chpl b/test/io/serializers/jsonHelpers/fromJsonThrows.chpl
new file mode 100644
index 000000000000..d4c9551c7c17
--- /dev/null
+++ b/test/io/serializers/jsonHelpers/fromJsonThrows.chpl
@@ -0,0 +1,20 @@
+import IO, JSON;
+
+record myRec {
+  var field: int;
+}
+
+var inFile = IO.open("fromJsonThrows.in", IO.ioMode.r);
+var inReader = inFile.reader();
+
+var rec: myRec;
+
+proc main() throws {
+  try {
+    rec = JSON.fromJson(inReader.readAll(string), myRec);
+    writeln(rec);
+  }
+  catch err: IllegalArgumentError {
+    writeln("Caught the error correctly");
+  }
+}
diff --git a/test/io/serializers/jsonHelpers/fromJsonThrows.cleanfiles b/test/io/serializers/jsonHelpers/fromJsonThrows.cleanfiles
new file mode 100644
index 000000000000..6fe0a2a75c1e
--- /dev/null
+++ b/test/io/serializers/jsonHelpers/fromJsonThrows.cleanfiles
@@ -0,0 +1 @@
+fromJsonThrows.in
diff --git a/test/io/serializers/jsonHelpers/fromJsonThrows.good b/test/io/serializers/jsonHelpers/fromJsonThrows.good
new file mode 100644
index 000000000000..c32344df3cbb
--- /dev/null
+++ b/test/io/serializers/jsonHelpers/fromJsonThrows.good
@@ -0,0 +1 @@
+Caught the error correctly
diff --git a/test/io/serializers/jsonHelpers/fromJsonThrows.preexec b/test/io/serializers/jsonHelpers/fromJsonThrows.preexec
new file mode 100755
index 000000000000..54898d467cc3
--- /dev/null
+++ b/test/io/serializers/jsonHelpers/fromJsonThrows.preexec
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo "{\"fiel\":10}" > fromJsonThrows.in