count special module methods once per name for completion

Author: kevinushey

ChangeLog

@@ -1,3 +1,12 @@
+2026-10-29  Kevin Ushey <kevinushey@gmail.com>
+
+	* inst/include/Rcpp/module/class.h (class_::AddMethod): Count special
+	'[' methods once per name rather than once per overload, as complete()
+	expects; overloading '[[' dropped methods from completion or ran past
+	the end of the method map (#1529)
+	* inst/tinytest/cpp/Module.cpp: Add classes overloading '[['
+	* inst/tinytest/test_module.R: Test their completions
+
 2026-10-23  Dirk Eddelbuettel  <edd@debian.org>
 
 	* DESCRIPTION (Version, Date): Roll micro version and date

inst/include/Rcpp/module/class.h

@@ -250,9 +250,10 @@
             typename map_vec_signed_method::iterator it = ptr->vec_methods.find( name_ ) ;
             if( it == ptr->vec_methods.end() ){
                 it = ptr->vec_methods.insert( vec_signed_method_pair( name_, new vec_signed_method() ) ).first ;
+                // complete() relies on this counting names, not overloads
+                if( *name_ == '[' ) ptr->specials++ ;
             }
             (it->second)->push_back( new signed_method_class(m, valid, docstring ) ) ;
-            if( *name_ == '[' ) ptr->specials++ ;
             return *this ;
         }
 

inst/tinytest/cpp/Module.cpp

@@ -137,6 +137,27 @@ double Test_get_x_pointer(ModuleTest* x) {
     return x->value;
 }
 
+class ModuleBrackets {
+public:
+    ModuleBrackets() : value(1.0) {}
+
+    double at(int i) { return value * i; }
+    double at2(int i, int j) { return value * i * j; }
+    double total() { return value; }
+
+    double value;
+};
+
+class ModuleBracketsOnly {
+public:
+    ModuleBracketsOnly() : value(1.0) {}
+
+    double at(int i) { return value * i; }
+    double at2(int i, int j) { return value * i * j; }
+
+    double value;
+};
+
 class ModuleGadget {
 public:
     ModuleGadget() {}
@@ -217,6 +238,22 @@ RCPP_MODULE(demoModule) {
         .method("get" , &ModuleRandomizer::get)
         ;
 
+    // overloaded [[, with and without an ordinary method
+    class_<ModuleBrackets>("ModuleBrackets")
+        .constructor()
+        .method("[[", &ModuleBrackets::at)
+        .method("[[", &ModuleBrackets::at2)
+        .method("total", &ModuleBrackets::total)
+        .field("value", &ModuleBrackets::value)
+        ;
+
+    class_<ModuleBracketsOnly>("ModuleBracketsOnly")
+        .constructor()
+        .method("[[", &ModuleBracketsOnly::at)
+        .method("[[", &ModuleBracketsOnly::at2)
+        .field("value", &ModuleBracketsOnly::value)
+        ;
+
     class_<ModuleGadget>("ModuleGadget")
         .constructor()
         .method("value", static_cast<void (ModuleGadget::*)(int)>(&ModuleGadget::value))

inst/tinytest/test_module.R

@@ -108,6 +108,14 @@ expect_equal(r$get(10), x10)
 r <- new( ModuleRandomizer )
 expect_error( r$get(10L), "not initialized" )
 
+## completion lists the ordinary methods and the fields; an overloaded [[
+## used to be counted once per overload, which dropped the last ordinary
+## method, or ran past the end of the method map when there was none (#1529)
+brackets <- new( ModuleBrackets )
+expect_equal( Rcpp:::complete( brackets ), c("total( ", "value") )
+expect_equal( brackets[[2L]], 2.0 )
+expect_equal( Rcpp:::complete( new( ModuleBracketsOnly ) ), "value" )
+
 #    test.Module.flexible.semantics <- function( ){
 expect_equal( test_reference( seq(0,10) ), 11L )
 expect_equal( test_const_reference( seq(0,10) ), 11L )