fix(extract): receiver-qualify Go method QNs

A Go method's QN was the flat package form (proj.pkg.method) — the
receiver was ignored, so every same-name method in a package collided
on one QN and the graph upsert kept exactly one node. Measured on a
real Go repo: 20 Process/Name methods across 15 files kept 2 nodes;
9 different Task() methods fused into one chimera node carrying all
nine bodies' call edges; 19 structs pointed DEFINES_METHOD at a single
shared method node; a _test.go mock Close outranked the production
Close in the dedupe tie-break. The upsert's own comment calls
kind-disambiguated QNs 'the real cure'.

Qualify the QN with the receiver type (proj.pkg.Recv.method), the same
shape as Go interface members and the C++ out-of-line method path
right below it in extract_func_def:

- extract_defs.c: def.qualified_name = parent_class + name whenever
  the receiver type resolves; go_receiver_type_name becomes the shared
  cbm_go_receiver_type_name (exported via helpers.h) so both sides of
  the contract use one formula.
- extract_unified.c (compute_func_qn): mirror branch for
  method_declaration, so method-body calls keep exact source
  attribution instead of degrading to File-node fallback
  (calls_find_source).
- Consumers already agree: pxc_build_lsp_def passes the def QN and
  parent_class (receiver_type) verbatim into the Go LSP registries,
  and check_go_class_implements explicitly supports class-qualified
  method QNs (its path (b)).

Side effect: resolve_same_module's exact module.name hash no longer
matches concrete methods, which kills the conf-0.9 false edges where
an interface-typed call bound to an unrelated same-package method.

Fixes #1909

Signed-off-by: Ilya Brykau <ilya.brykau@orca.security>

internal/cbm/extract_defs.c

@@ -3521,7 +3521,7 @@ static void set_def_complexity(CBMDefinition *def, TSNode body, const CBMLangSpe
  * Walks to the parameter_declaration's `type` field, unwrapping pointer_type
  * and generic_type, and returns the type_identifier text (e.g. "OrderService").
  * Returns NULL if no type_identifier is found. */
-static char *go_receiver_type_name(CBMArena *a, TSNode recv, const char *source) {
+char *cbm_go_receiver_type_name(CBMArena *a, TSNode recv, const char *source) {
     uint32_t nc = ts_node_child_count(recv);
     for (uint32_t i = 0; i < nc; i++) {
         TSNode child = ts_node_child(recv, i);
@@ -3733,12 +3733,22 @@ static void extract_func_def(CBMExtractCtx *ctx, TSNode node, const CBMLangSpec
          * (and downstream Go IMPLEMENTS/OVERRIDE) link the method to its owning
          * struct/type node.  The parent QN must match the type's node QN, which
          * is computed the same way (cbm_fqn_compute on the type name). */
-        char *recv_type = go_receiver_type_name(a, recv, ctx->source);
+        char *recv_type = cbm_go_receiver_type_name(a, recv, ctx->source);
         if (recv_type && recv_type[0]) {
             /* Must match the Go type node QN (directory-based module) so the
              * DEFINES_METHOD edge links the method to its owning type. */
             def.parent_class = cbm_fqn_compute_source_lang(a, ctx->project, ctx->rel_path,
                                                            recv_type, ctx->language);
+            /* Receiver-qualify the method QN (proj.pkg.Recv.method) — same
+             * shape as the C++ out-of-line path below and Go interface
+             * members. With the flat proj.pkg.method QN every same-name
+             * method in a package collided in the graph upsert: one body
+             * survived and the twins' call edges accreted onto it. The
+             * call-scope side (compute_func_qn in extract_unified.c) mirrors
+             * this formula, and go_lsp consumers read the def QN and
+             * parent_class (receiver_type) verbatim, so resolution joins
+             * stay exact. */
+            def.qualified_name = cbm_arena_sprintf(a, "%s.%s", def.parent_class, name);
         }
     }
 

internal/cbm/extract_unified.c

@@ -1087,6 +1087,25 @@ static const char *compute_func_qn(CBMExtractCtx *ctx, TSNode node, const CBMLan
         }
     }
 
+    /* Go method `func (s *Storage) Close() {...}`: the def extractor records
+     * this as Method "proj.pkg.Storage.Close" (receiver-qualified, mirroring
+     * the C++ out-of-line rule above). The call-scope QN must match — a bare
+     * "proj.pkg.Close" names a node that no longer exists, so every call
+     * inside the method body would fall back to File-node attribution
+     * (calls_find_source). Same ONE-formula contract as the def side:
+     * cbm_go_receiver_type_name + cbm_fqn_compute_source_lang. */
+    if (ctx->language == CBM_LANG_GO && strcmp(ts_node_type(node), "method_declaration") == 0) {
+        TSNode recv = ts_node_child_by_field_name(node, TS_FIELD("receiver"));
+        if (!ts_node_is_null(recv)) {
+            char *recv_type = cbm_go_receiver_type_name(ctx->arena, recv, ctx->source);
+            if (recv_type && recv_type[0]) {
+                const char *type_qn = cbm_fqn_compute_source_lang(
+                    ctx->arena, ctx->project, ctx->rel_path, recv_type, ctx->language);
+                return cbm_arena_sprintf(ctx->arena, "%s.%s", type_qn, name);
+            }
+        }
+    }
+
     /* Nix: a binding's own attrpath contributes scope (`a.b.fn = …`), and the def
      * extractor bakes it into the def QN. Compose it identically here — otherwise
      * an in-body call sources to a QN one or more segments short of the def, and

internal/cbm/helpers.h

@@ -119,6 +119,12 @@ TSNode cbm_resolve_func_name(TSNode node, CBMLanguage lang);
 // def extractor — drift dropped the class qualifier from in-body calls (#554/#621).
 char *cbm_cpp_out_of_line_parent_class(CBMArena *a, TSNode node, const char *source);
 
+/* Go: resolve a method_declaration's receiver parameter_list down to the bare
+ * receiver type_identifier (unwrapping pointer_type / generic_type). Shared by
+ * def extraction (extract_defs.c) and call-scope attribution
+ * (extract_unified.c) so the receiver-qualified method QN has ONE formula. */
+char *cbm_go_receiver_type_name(CBMArena *a, TSNode recv, const char *source);
+
 // Find a child node by kind string.
 TSNode cbm_find_child_by_kind(TSNode parent, const char *kind);
 

internal/cbm/lsp/go_lsp.c

@@ -1861,15 +1861,24 @@ static void process_function(GoLSPContext* ctx, TSNode func_node) {
     char* func_name = lsp_node_text(ctx, name_node);
     if (!func_name || !func_name[0]) return;
 
-    // Enclosing-function QN must be the BARE package.Func form (no receiver
-    // type segment). The textual call events (extract_unified.c) source calls
-    // as package_qn.func_name — methods included — and the defs pass creates
-    // the graph Method node under the same QN, so any other form breaks the
-    // caller-QN join in cbm_pipeline_find_lsp_resolution and the LSP-resolved
-    // call silently falls back to the registry short-name resolver. The
-    // receiver type still reaches the registry via the def's parent_class /
-    // method->receiver_type; it just does not appear in the caller QN.
+    // Enclosing-function QN must be EXACTLY the QN the textual call events
+    // (extract_unified.c compute_func_qn) and the defs pass produce, or the
+    // caller-QN join in cbm_pipeline_find_lsp_resolution breaks and the
+    // LSP-resolved call silently falls back to the registry short-name
+    // resolver. Since #1909 receiver-qualified Go method QNs, that shared
+    // form is package_qn.ReceiverType.method for methods (the ONE-formula
+    // contract: cbm_go_receiver_type_name) and package_qn.func for functions.
     ctx->enclosing_func_qn = cbm_arena_sprintf(ctx->arena, "%s.%s", ctx->package_qn, func_name);
+    if (strcmp(ts_node_type(func_node), "method_declaration") == 0) {
+        TSNode recv = ts_node_child_by_field_name(func_node, "receiver", 8);
+        if (!ts_node_is_null(recv)) {
+            char *recv_type = cbm_go_receiver_type_name(ctx->arena, recv, ctx->source);
+            if (recv_type && recv_type[0]) {
+                ctx->enclosing_func_qn = cbm_arena_sprintf(ctx->arena, "%s.%s.%s", ctx->package_qn,
+                                                           recv_type, func_name);
+            }
+        }
+    }
 
     // Push function scope
     CBMScope* saved_scope = ctx->current_scope;

tests/test_extraction.c

@@ -4715,12 +4715,12 @@ TEST(extract_go_no_filename_in_module_qn) {
     ASSERT_NOT_NULL(conn);
     ASSERT_STR_EQ(conn->qualified_name, "proj.myapp.db.Conn");
 
-    /* Go method nodes keep a FLAT QN (module + name) with a separate
-     * parent_class link to the receiver type — the QN must carry the
+    /* Go method nodes carry a receiver-qualified QN (module + receiver type +
+     * name) plus the parent_class link — the QN must carry the
      * directory-based module and NOT the `.conn.` filename segment. */
     const CBMDefinition *query = find_def_by_name(r, "Query");
     ASSERT_NOT_NULL(query);
-    ASSERT_STR_EQ(query->qualified_name, "proj.myapp.db.Query");
+    ASSERT_STR_EQ(query->qualified_name, "proj.myapp.db.Conn.Query");
     ASSERT_EQ(strstr(query->qualified_name, ".conn."), NULL);
     /* The method's parent_class must match the type node QN (for DEFINES_METHOD). */
     ASSERT_NOT_NULL(query->parent_class);
@@ -5501,6 +5501,49 @@ TEST(extract_python_bare_call_flag_is_depth_independent) {
     PASS();
 }
 
+TEST(extract_go_method_receiver_qualified_qn) {
+    /* A Go method QN carries the receiver type (proj.pkg.Recv.method), same
+     * shape as C++ out-of-line methods and Go interface members — so two
+     * same-name methods on different receivers no longer collide in the
+     * graph upsert. Free functions keep the flat package QN. */
+    CBMFileResult *r = extract("package m\n"
+                               "type Storage struct{}\n"
+                               "type Cache struct{}\n"
+                               "func (s *Storage) Close() {}\n"
+                               "func (c Cache) Close() {}\n"
+                               "func Shutdown() {}\n",
+                               CBM_LANG_GO, "t", "x.go");
+    ASSERT_NOT_NULL(r);
+    ASSERT_FALSE(r->has_error);
+    bool saw_storage = false;
+    bool saw_cache = false;
+    bool saw_free = false;
+    for (int i = 0; i < r->defs.count; i++) {
+        const CBMDefinition *d = &r->defs.items[i];
+        if (!d->name || !d->qualified_name) {
+            continue;
+        }
+        if (strcmp(d->name, "Close") == 0 && strcmp(d->qualified_name, "t.Storage.Close") == 0) {
+            ASSERT_STR_EQ(d->label, "Method");
+            ASSERT_STR_EQ(d->parent_class, "t.Storage");
+            saw_storage = true;
+        }
+        if (strcmp(d->name, "Close") == 0 && strcmp(d->qualified_name, "t.Cache.Close") == 0) {
+            ASSERT_STR_EQ(d->parent_class, "t.Cache");
+            saw_cache = true;
+        }
+        if (strcmp(d->name, "Shutdown") == 0) {
+            ASSERT_STR_EQ(d->qualified_name, "t.Shutdown");
+            saw_free = true;
+        }
+    }
+    ASSERT_TRUE(saw_storage);
+    ASSERT_TRUE(saw_cache);
+    ASSERT_TRUE(saw_free);
+    cbm_free_result(r);
+    PASS();
+}
+
 /* TS/JS/TSX receiver-aware flag (#592/#606; same intent as the Perl flag above).
  * A member call x.foo() with a non-this/super receiver is flagged is_method so
  * the resolver can suppress a weak short-name match (`re.test()` must not bind a
@@ -7541,6 +7584,7 @@ SUITE(extraction) {
     RUN_TEST(extract_python_bare_call_flags_locally_bound_callee);
     RUN_TEST(extract_python_bare_call_flag_is_depth_independent);
     RUN_TEST(extract_go_selector_call_flags_is_method);
+    RUN_TEST(extract_go_method_receiver_qualified_qn);
     RUN_TEST(extract_ts_member_call_flags_is_method);
     RUN_TEST(extract_ts_this_super_receiver_not_flagged);
     RUN_TEST(extract_js_member_call_flags_is_method);

tests/test_parallel.c

@@ -3444,8 +3444,9 @@ TEST(parallel_go_cross_package_field_chain_resolves) {
     cbm_gbuf_t *gbuf = run_go_field_chain_sequential("go_field_fold", tmpdir, files, 2);
     ASSERT_NOT_NULL(gbuf);
 
-    const cbm_gbuf_edge_t *edge =
-        find_call_edge_to_target_fragment(gbuf, "handler.PlaceOrder", ".service.PlaceOrder");
+    /* Since #1909, Go method QNs are receiver-qualified on both endpoints. */
+    const cbm_gbuf_edge_t *edge = find_call_edge_to_target_fragment(
+        gbuf, "OrderHandler.PlaceOrder", ".service.OrderService.PlaceOrder");
     const bool found = edge != NULL;
     const bool dispatch = edge && edge->properties_json &&
                           strstr(edge->properties_json, "\"strategy\":\"lsp_type_dispatch\"");

tests/test_pipeline.c

@@ -5467,6 +5467,57 @@ TEST(pipeline_python_receiver_suppresses_weak_method_edge) {
     PASS();
 }
 
+TEST(pipeline_go_method_caller_keeps_lsp_join) {
+    /* #1909: receiver-qualifying method QNs moves the def/textual-call QN to
+     * package.Type.method — go_lsp's enclosing-function QN must move with it
+     * (the ONE-formula contract), or every LSP resolution sourced from inside
+     * a method body loses its caller join and the edge dies. The callee name
+     * collides across receivers so no short-name fallback can mask the loss. */
+    char tmp[256];
+    snprintf(tmp, sizeof(tmp), "/tmp/cbm_go_mcall_XXXXXX");
+    if (!cbm_mkdtemp(tmp)) {
+        FAIL("tmpdir");
+    }
+    write_temp_file(tmp, "go.mod", "module example.com/fxmcall\n\ngo 1.22\n");
+    write_temp_file(tmp, "svc/repo.go",
+                    "package svc\n"
+                    "\n"
+                    "type Repo struct {\n"
+                    "\tn int\n"
+                    "}\n"
+                    "\n"
+                    "func (r *Repo) Install() int {\n"
+                    "\treturn r.helper()\n"
+                    "}\n");
+    write_temp_file(tmp, "svc/helper.go",
+                    "package svc\n"
+                    "\n"
+                    "func (r *Repo) helper() int {\n"
+                    "\treturn r.n\n"
+                    "}\n");
+    write_temp_file(tmp, "other/other.go",
+                    "package other\n"
+                    "\n"
+                    "type Decoy struct{}\n"
+                    "\n"
+                    "func (d *Decoy) helper() int { return 2 }\n");
+
+    char db_path[512];
+    snprintf(db_path, sizeof(db_path), "%s/go_mcall.db", tmp);
+    cbm_pipeline_t *p = cbm_pipeline_new(tmp, db_path, CBM_MODE_FULL);
+    ASSERT_NOT_NULL(p);
+    ASSERT_EQ(cbm_pipeline_run(p), 0);
+    const char *project = cbm_pipeline_project_name(p);
+
+    cbm_store_t *s = cbm_store_open_path(db_path);
+    ASSERT_NOT_NULL(s);
+    ASSERT_TRUE(cross_file_call_exists(s, project, "Install", "helper"));
+    cbm_store_close(s);
+    cbm_pipeline_free(p);
+    th_rmtree(tmp);
+    PASS();
+}
+
 TEST(pipeline_go_receiver_suppresses_weak_method_edge) {
     char tmp[256];
     snprintf(tmp, sizeof(tmp), "/tmp/cbm_go_recv_XXXXXX");
@@ -14687,6 +14738,7 @@ SUITE(pipeline) {
 #endif
     RUN_TEST(pipeline_tsjs_receiver_suppresses_weak_method_edge);
     RUN_TEST(pipeline_python_receiver_suppresses_weak_method_edge);
+    RUN_TEST(pipeline_go_method_caller_keeps_lsp_join);
     RUN_TEST(pipeline_go_receiver_suppresses_weak_method_edge);
     RUN_TEST(pipeline_go_rw_usage_never_cross_into_c);
     RUN_TEST(pipeline_go_rw_usage_never_cross_into_c_parallel);