if (try foo) was handled incorrectly inside a defer.

releasenotes.md

@@ -40,6 +40,7 @@
 - Empty expression block would crash compiler with debug on #1554.
 - Improve infer conversions on constants, e.g. `ZString a = foo ? "a" : "b";` #1561
 - Show error when declarations do not start with `fn` in interfaces. #1565
+- `if (try foo)` was handled incorrectly inside a defer.
 
 ### Stdlib changes
 - Remove unintended print of `char[]` as String

src/compiler/copying.c

@@ -372,7 +372,14 @@ Expr *copy_expr(CopyStruct *c, Expr *source_expr)
 				}
 				else
 				{
-					MACRO_COPY_DECL(expr->try_unwrap_expr.decl);
+					if (expr->try_unwrap_expr.optional)
+					{
+						MACRO_COPY_DECL(expr->try_unwrap_expr.decl);
+					}
+					else
+					{
+						fixup_decl(c, &expr->try_unwrap_expr.decl);
+					}
 				}
 			}
 			return expr;

test/test_suite/statements/defer_if_try_copy.c3t

@@ -0,0 +1,36 @@
+// #target: macos-x64
+module foo;
+import std;
+fn int main()
+{
+    int! cmd = 3;
+    defer
+    {
+        if (try cmd) { io::printfn("HO! %s", cmd); }
+    }
+    return 0;
+}
+/* #expect: foo.ll
+
+define i32 @main() #0 {
+entry:
+  %cmd = alloca i32, align 4
+  %cmd.f = alloca i64, align 8
+  %varargslots = alloca [1 x %any], align 16
+  %retparam = alloca i64, align 8
+  store i32 3, ptr %cmd, align 4
+  store i64 0, ptr %cmd.f, align 8
+  %load.err = load i64, ptr %cmd.f, align 8
+  %result = icmp eq i64 %load.err, 0
+  br i1 %result, label %if.then, label %if.exit
+
+if.then:                                          ; preds = %entry
+  %0 = insertvalue %any undef, ptr %cmd, 0
+  %1 = insertvalue %any %0, i64 ptrtoint (ptr @"$ct.int" to i64), 1
+  store %any %1, ptr %varargslots, align 16
+  %2 = call i64 @std.io.printfn(ptr %retparam, ptr @.str, i64 6, ptr %varargslots, i64 1)
+  br label %if.exit
+
+if.exit:                                          ; preds = %if.then, %entry
+  ret i32 0
+}