test(extern): call functions from a user C object

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

5 files changed, 41 insertions, 0 deletions

diff --git a/tests/i/extern-c-object/case.json b/tests/i/extern-c-object/case.json
new file mode 100644
index 0000000..1ce5970
--- /dev/null
+++ b/tests/i/extern-c-object/case.json
@@ -0,0 +1,5 @@
+{
+  "objects": [
+    {"source": "lib.c", "output": "lib.o"}
+  ]
+}
diff --git a/tests/i/extern-c-object/expected.txt b/tests/i/extern-c-object/expected.txt
new file mode 100644
index 0000000..58ebb6d
--- /dev/null
+++ b/tests/i/extern-c-object/expected.txt
@@ -0,0 +1,6 @@
+6
+10.000000
+9
+1
+2
+from lib.c
diff --git a/tests/i/extern-c-object/lib.c b/tests/i/extern-c-object/lib.c
new file mode 100644
index 0000000..568133d
--- /dev/null
+++ b/tests/i/extern-c-object/lib.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <string.h>
+
+static int calls;
+
+int add3(int a, int b, int c) { return a + b + c; }
+double scale(double x, int k) { return x * k; }
+int name_length(const char *s) { return (int)strlen(s); }
+int next_call(void) { return ++calls; }
+void say(const char *s) { puts(s); }
diff --git a/tests/i/extern-c-object/notes.md b/tests/i/extern-c-object/notes.md
new file mode 100644
index 0000000..51af8cb
--- /dev/null
+++ b/tests/i/extern-c-object/notes.md
@@ -0,0 +1,7 @@
+# extern-c-object
+
+Human review: pending. Expected output was independently traced by AI, not captured from cpsc.
+
+Basis: compiler extension (EXTERN "C", INCLUDE_OBJ of a user object); C semantics.
+
+Trace: the harness compiles `lib.c` with the host C compiler (`objects` in `case.json`). add3(1,2,3)=6. scale(2.5,4)=10.0, printed like other C doubles as `10.000000`. name_length("cambridge")=9. next_call increments a static counter in the object, giving 1 then 2. say calls puts, which prints the string and a newline.
diff --git a/tests/i/extern-c-object/program.cps b/tests/i/extern-c-object/program.cps
new file mode 100644
index 0000000..5ac34ec
--- /dev/null
+++ b/tests/i/extern-c-object/program.cps
@@ -0,0 +1,13 @@
+// Functions from a user C object built with the host C compiler.
+INCLUDE_OBJ "lib.o"
+EXTERN "C" EXTERN_FUNCTION add3(C_INT, C_INT, C_INT) RETURNS C_INT
+EXTERN "C" EXTERN_FUNCTION scale(C_DOUBLE, C_INT) RETURNS C_DOUBLE
+EXTERN "C" EXTERN_FUNCTION name_length(C_STRING) RETURNS C_INT
+EXTERN "C" EXTERN_FUNCTION next_call() RETURNS C_INT
+EXTERN "C" EXTERN_PROCEDURE say(C_STRING)
+OUTPUT add3((C_INT)1, (C_INT)2, (C_INT)3)
+OUTPUT scale((C_DOUBLE)2.5, (C_INT)4)
+OUTPUT name_length((C_STRING)"cambridge")
+OUTPUT next_call()
+OUTPUT next_call()
+CALL say((C_STRING)"from lib.c")