When a for loop variable is in, declare the use of the range as_const too, see #226

Author: hsutter

regression-tests/test-results/mixed-bounds-safety-with-assert-2.cpp

@@ -20,7 +20,7 @@ auto add_42_to_subrange(auto& rng, cpp2::in<int> start, cpp2::in<int> end) -> vo
     std::vector<int> v {1, 2, 3, 4, 5}; 
     add_42_to_subrange(v, 1, 3);
 
-    for ( auto&& cpp2_range = v;  auto const& i : cpp2_range ) 
+    for ( auto&& cpp2_range = std::as_const(v);  auto const& i : cpp2_range ) 
         std::cout << i << "\n";
 }
 

regression-tests/test-results/mixed-bounds-safety-with-assert.cpp

@@ -26,7 +26,7 @@ auto print_subrange(auto const& rng, cpp2::in<int> start, cpp2::in<int> end) ->
     cpp2::Bounds.expects(cpp2::cmp_less_eq(end,CPP2_UFCS_0(ssize, rng)), "");
 
     auto count {0}; 
-    for ( auto&& cpp2_range = rng;  
+    for ( auto&& cpp2_range = std::as_const(rng);  
 
           auto const& i : cpp2_range )  { do 
         if (cpp2::cmp_less_eq(start,count) && cpp2::cmp_less_eq(count,end)) {

regression-tests/test-results/mixed-function-expression-and-std-for-each.cpp

@@ -34,7 +34,7 @@
         std::move(callback)
     );
 
-    for ( auto&& cpp2_range = view;  auto const& str : cpp2_range ) {
+    for ( auto&& cpp2_range = std::as_const(view);  auto const& str : cpp2_range ) {
         std::cout << str << "\n";
     }
 }

regression-tests/test-results/mixed-function-expression-and-std-ranges-for-each-with-capture.cpp

@@ -27,7 +27,7 @@
     auto callback {[](auto& x) { return x += "-ish"; }}; 
     std::ranges::for_each( view, std::move(callback));
 
-    for ( auto&& cpp2_range = view;  auto const& str : cpp2_range ) 
+    for ( auto&& cpp2_range = std::as_const(view);  auto const& str : cpp2_range ) 
         std::cout << str << "\n";
 }
 

regression-tests/test-results/mixed-function-expression-and-std-ranges-for-each.cpp

@@ -26,7 +26,7 @@
     auto callback {[](auto& x) { return x += "-ish"; }}; 
     std::ranges::for_each( view, std::move(callback));
 
-    for ( auto&& cpp2_range = view;  auto const& str : cpp2_range ) 
+    for ( auto&& cpp2_range = std::as_const(view);  auto const& str : cpp2_range ) 
         std::cout << str << "\n";
 }
 

regression-tests/test-results/mixed-function-expression-with-pointer-capture.cpp

@@ -28,7 +28,7 @@
     auto callback {[](auto& x) { return x += "-ish"; }}; 
     std::ranges::for_each( view, std::move(callback));
 
-    for ( auto&& cpp2_range = view;  auto const& str : cpp2_range ) 
+    for ( auto&& cpp2_range = std::as_const(view);  auto const& str : cpp2_range ) 
         std::cout << str << "\n";
 }
 

regression-tests/test-results/mixed-function-expression-with-repeated-capture.cpp

@@ -27,7 +27,7 @@
     auto callback {[](auto& x) { return x += "-ish"; }}; 
     std::ranges::for_each( view, std::move(callback));
 
-    for ( auto&& cpp2_range = view;  auto const& str : cpp2_range ) 
+    for ( auto&& cpp2_range = std::as_const(view);  auto const& str : cpp2_range ) 
         std::cout << str << "\n";
 }
 

regression-tests/test-results/mixed-intro-for-with-counter-include-last.cpp

@@ -18,7 +18,7 @@
 {
     std::vector<int> v {1, 2, 3, 4, 5}; 
     auto counter {42}; 
-    for ( auto&& cpp2_range = v;   auto const& i : cpp2_range )  { do {
+    for ( auto&& cpp2_range = std::as_const(v);  auto const& i : cpp2_range )  { do {
         std::cout << i << " " << counter << "\n";
     } while (false); counter *= 2; }
 }

regression-tests/test-results/pure2-break-continue.cpp

@@ -196,9 +196,9 @@ auto for_continue_inner() -> void
 {
     std::vector vi {0, 1, 2}; 
     auto counter {0}; 
-    for ( auto&& cpp2_range = vi;  auto const& i : cpp2_range )  { do {
+    for ( auto&& cpp2_range = std::as_const(vi);  auto const& i : cpp2_range )  { do {
         std::vector vj {0, 1, 2}; 
-        for ( auto&& cpp2_range = vj;  auto const& j : cpp2_range ) {{
+        for ( auto&& cpp2_range = std::as_const(vj);  auto const& j : cpp2_range ) {{
             std::cout << i << j << " ";
             if (j == 1) {
                 goto CONTINUE_166_9;
@@ -214,9 +214,9 @@ auto for_continue_outer() -> void
 {
     std::vector vi {0, 1, 2}; 
     auto counter {0}; 
-    for ( auto&& cpp2_range = vi;     auto const& i : cpp2_range ) { { do {
+    for ( auto&& cpp2_range = std::as_const(vi);  auto const& i : cpp2_range ) { { do {
         std::vector vj {0, 1, 2}; 
-        for ( auto&& cpp2_range = vj;  auto const& j : cpp2_range ) {
+        for ( auto&& cpp2_range = std::as_const(vj);  auto const& j : cpp2_range ) {
             std::cout << i << j << " ";
             if (j == 1) {
                 goto CONTINUE_182_5;
@@ -232,9 +232,9 @@ auto for_break_inner() -> void
 {
     std::vector vi {0, 1, 2}; 
     auto counter {0}; 
-    for ( auto&& cpp2_range = vi;  auto const& i : cpp2_range )  { do {
+    for ( auto&& cpp2_range = std::as_const(vi);  auto const& i : cpp2_range )  { do {
         std::vector vj {0, 1, 2}; 
-        for ( auto&& cpp2_range = vj;  auto const& j : cpp2_range ) {{
+        for ( auto&& cpp2_range = std::as_const(vj);  auto const& j : cpp2_range ) {{
             std::cout << i << j << " ";
             if (j == 1) {
                 goto BREAK_202_9;
@@ -250,9 +250,9 @@ auto for_break_outer() -> void
 {
     std::vector vi {0, 1, 2}; 
     auto counter {0}; 
-    for ( auto&& cpp2_range = vi;     auto const& i : cpp2_range ) { { do {
+    for ( auto&& cpp2_range = std::as_const(vi);  auto const& i : cpp2_range ) { { do {
         std::vector vj {0, 1, 2}; 
-        for ( auto&& cpp2_range = vj;  auto const& j : cpp2_range ) {
+        for ( auto&& cpp2_range = std::as_const(vj);  auto const& j : cpp2_range ) {
             std::cout << i << j << " ";
             if (j == 1) {
                 goto BREAK_218_5;

source/cppfront.cpp

@@ -1545,7 +1545,13 @@ class cppfront
             assert(!n.condition && !n.statement && n.range && n.body);
 
             printer.print_cpp2("for ( auto&& cpp2_range = ", n.position());
+            if (n.for_with_in) {
+                printer.print_cpp2("std::as_const(", n.position());
+            }
             emit(*n.range);
+            if (n.for_with_in) {
+                printer.print_cpp2(")", n.position());
+            }
             printer.print_cpp2(";  ", n.position());
             emit(*n.get_for_parameter());
             printer.print_cpp2(" : cpp2_range ) ", n.position());

source/parse.h

@@ -765,6 +765,7 @@ struct iteration_statement_node
     std::unique_ptr<compound_statement_node>    statement;          // used for "do" and "while", else null
     std::unique_ptr<expression_node>            range;              // used for "for", else null
     std::unique_ptr<declaration_node>           body;               // used for "for", else null
+    bool                                        for_with_in = false;// usse for "for," says whether loop variable is 'in'
 
     auto get_for_parameter() const -> parameter_declaration_node const*;
 
@@ -2709,6 +2710,11 @@ class parser
                 error("for..do loop body must be an unnamed function taking a single parameter and returning nothing", false);
                 return {};
             }
+            //  else
+            assert(func && *func);
+            if ((**func).parameters->parameters.front()->pass == passing_style::in) {
+                n->for_with_in = true;
+            }
 
             return n;
         }