Improved (and simplified) for loop code generation

See commit comment thread:
2c64707

Author: hsutter

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

@@ -31,9 +31,8 @@ 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);
 
-    { auto const& cpp2_range = v; for ( auto const& i : cpp2_range ) 
-        std::cout << i << "\n";}
-#line 8 "mixed-bounds-safety-with-assert-2.cpp2"
+    for ( auto const& i : v ) 
+        std::cout << i << "\n";
 }
 
 auto add_42_to_subrange(auto& rng, cpp2::in<int> start, cpp2::in<int> end) -> void
@@ -42,12 +41,11 @@ auto add_42_to_subrange(auto& rng, cpp2::in<int> start, cpp2::in<int> end) -> vo
     cpp2::Bounds.expects(cpp2::cmp_less_eq(end,CPP2_UFCS_0(ssize, rng)), "");
 
     auto count {0}; 
-    { auto&& cpp2_range = rng; for ( 
+    for ( 
 
-          auto&  i : cpp2_range )  { do 
+          auto&  i : rng )  { do 
         if ([_0 = start, _1 = count, _2 = end]{ return cpp2::cmp_less_eq(_0,_1) && cpp2::cmp_less_eq(_1,_2); }()) {
             i += 42;
-        } while (false); ++count; }}
-#line 22 "mixed-bounds-safety-with-assert-2.cpp2"
+        } while (false); ++count; }
 }
 

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

@@ -38,12 +38,11 @@ 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}; 
-    { auto const& cpp2_range = rng; for ( 
+    for ( 
 
-          auto const& i : cpp2_range )  { do 
+          auto const& i : rng )  { do 
         if (cpp2::cmp_less_eq(start,count) && cpp2::cmp_less_eq(count,end)) {
             std::cout << i << "\n";
-        } while (false); ++count; }}
-#line 18 "mixed-bounds-safety-with-assert.cpp2"
+        } while (false); ++count; }
 }
 

regression-tests/test-results/mixed-fixed-type-aliases.cpp

@@ -44,8 +44,7 @@ auto test(auto const& x) -> void{
     cpp2::u16 z {42}; 
     test(std::move(z));
 
-    { auto const& cpp2_range = args; for ( auto const& arg : cpp2_range ) 
-        std::cout << arg << "\n";}
-#line 24 "mixed-fixed-type-aliases.cpp2"
+    for ( auto const& arg : args ) 
+        std::cout << arg << "\n";
 }
 

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

@@ -43,9 +43,8 @@
         std::move(callback)
     );
 
-    { auto const& cpp2_range = view; for ( auto const& str : cpp2_range ) {
+    for ( auto const& str : view ) {
         std::cout << str << "\n";
-    }}
-#line 30 "mixed-function-expression-and-std-for-each.cpp2"
+    }
 }
 

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

@@ -36,8 +36,7 @@
     auto callback {[](auto& x) -> void { x += "-ish";  }}; 
     std::ranges::for_each(view, std::move(callback));
 
-    { auto const& cpp2_range = view; for ( auto const& str : cpp2_range ) 
-        std::cout << str << "\n";}
-#line 22 "mixed-function-expression-and-std-ranges-for-each-with-capture.cpp2"
+    for ( auto const& str : view ) 
+        std::cout << str << "\n";
 }
 

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

@@ -35,8 +35,7 @@
     auto callback {[](auto& x) -> void { x += "-ish";  }}; 
     std::ranges::for_each(view, std::move(callback));
 
-    { auto const& cpp2_range = view; for ( auto const& str : cpp2_range ) 
-        std::cout << str << "\n";}
-#line 21 "mixed-function-expression-and-std-ranges-for-each.cpp2"
+    for ( auto const& str : view ) 
+        std::cout << str << "\n";
 }
 

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

@@ -37,8 +37,7 @@
     auto callback {[](auto& x) -> void { x += "-ish";  }}; 
     std::ranges::for_each(view, std::move(callback));
 
-    { auto const& cpp2_range = view; for ( auto const& str : cpp2_range ) 
-        std::cout << str << "\n";}
-#line 23 "mixed-function-expression-with-pointer-capture.cpp2"
+    for ( auto const& str : view ) 
+        std::cout << str << "\n";
 }
 

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

@@ -36,8 +36,7 @@
     auto callback {[](auto& x) -> void { x += "-ish";  }}; 
     std::ranges::for_each(view, std::move(callback));
 
-    { auto const& cpp2_range = view; for ( auto const& str : cpp2_range ) 
-        std::cout << str << "\n";}
-#line 22 "mixed-function-expression-with-repeated-capture.cpp2"
+    for ( auto const& str : view ) 
+        std::cout << str << "\n";
 }
 

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

@@ -27,9 +27,8 @@
 {
     std::vector<int> v {1, 2, 3, 4, 5}; 
     auto counter {42}; 
-    { auto const& cpp2_range = v; for ( auto const& i : cpp2_range )  { do {
+    for (                         auto const& i : v )  { do {
         std::cout << i << " " << counter << "\n";
-    } while (false); counter *= 2; }}
-#line 9 "mixed-intro-for-with-counter-include-last.cpp2"
+    } while (false); counter *= 2; }
 }
 

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

@@ -253,87 +253,83 @@ auto for_continue_inner() -> void
 {
     std::vector vi {0, 1, 2}; 
     auto counter {0}; 
-    { auto const& cpp2_range = vi; for ( auto const& i : cpp2_range )  { do {
+    for ( auto const& i : vi )  { do {
         std::vector vj {0, 1, 2}; 
-        { auto const& cpp2_range = vj; for ( auto const& j : cpp2_range ) {
+        for ( auto const& j : vj ) {
 #line 166 "pure2-break-continue.cpp2"
         {
             std::cout << i << j << " ";
             if (j==1) {
                 goto CONTINUE_166_9;
             }
             std::cout << "inner ";
-        } CPP2_CONTINUE_BREAK(166_9) }}
+        } CPP2_CONTINUE_BREAK(166_9) }
 
 #line 174 "pure2-break-continue.cpp2"
         std::cout << "outer ";
-    } while (false); ++counter; }}
-#line 176 "pure2-break-continue.cpp2"
+    } while (false); ++counter; }
 }
 
 auto for_continue_outer() -> void
 {
     std::vector vi {0, 1, 2}; 
     auto counter {0}; 
-    { auto const& cpp2_range = vi; for ( auto const& i : cpp2_range ) {
+    for ( auto const& i : vi ) {
 #line 182 "pure2-break-continue.cpp2"
      { do {
         std::vector vj {0, 1, 2}; 
-        { auto const& cpp2_range = vj; for ( auto const& j : cpp2_range ) {
+        for ( auto const& j : vj ) {
             std::cout << i << j << " ";
             if (j==1) {
                 goto CONTINUE_182_5;
             }
             std::cout << "inner ";
-        }}
+        }
 
-#line 192 "pure2-break-continue.cpp2"
         std::cout << "outer ";
-    } while (false); ++counter; } CPP2_CONTINUE_BREAK(182_5) }}
+    } while (false); ++counter; } CPP2_CONTINUE_BREAK(182_5) }
 #line 194 "pure2-break-continue.cpp2"
 }
 
 auto for_break_inner() -> void
 {
     std::vector vi {0, 1, 2}; 
     auto counter {0}; 
-    { auto const& cpp2_range = vi; for ( auto const& i : cpp2_range )  { do {
+    for ( auto const& i : vi )  { do {
         std::vector vj {0, 1, 2}; 
-        { auto const& cpp2_range = vj; for ( auto const& j : cpp2_range ) {
+        for ( auto const& j : vj ) {
 #line 202 "pure2-break-continue.cpp2"
         {
             std::cout << i << j << " ";
             if (j==1) {
                 goto BREAK_202_9;
             }
             std::cout << "inner ";
-        } CPP2_CONTINUE_BREAK(202_9) }}
+        } CPP2_CONTINUE_BREAK(202_9) }
 
 #line 210 "pure2-break-continue.cpp2"
         std::cout << "outer ";
-    } while (false); ++counter; }}
-#line 212 "pure2-break-continue.cpp2"
+    } while (false); ++counter; }
 }
 
 auto for_break_outer() -> void
 {
     std::vector vi {0, 1, 2}; 
     auto counter {0}; 
-    { auto const& cpp2_range = vi; for ( auto const& i : cpp2_range ) {
+    for ( auto const& i : vi ) {
 #line 218 "pure2-break-continue.cpp2"
      { do {
         std::vector vj {0, 1, 2}; 
-        { auto const& cpp2_range = vj; for ( auto const& j : cpp2_range ) {
+        for ( auto const& j : vj ) {
             std::cout << i << j << " ";
             if (j==1) {
                 goto BREAK_218_5;
             }
             std::cout << "inner ";
-        }}
+        }
 
-#line 228 "pure2-break-continue.cpp2"
         std::cout << "outer ";
-    } while (false); ++counter; } CPP2_CONTINUE_BREAK(218_5) }}
+    } while (false); ++counter; } CPP2_CONTINUE_BREAK(218_5) }
 #line 230 "pure2-break-continue.cpp2"
 }
 

regression-tests/test-results/pure2-intro-example-hello-2022.cpp

@@ -30,11 +30,10 @@ auto println(auto const& x, auto const& len) -> void;
             "hello", "2022"}; 
     std::span view {vec}; 
 
-    { auto&& cpp2_range = view; for ( auto& str : cpp2_range ) {
+    for ( auto& str : view ) {
         auto len {decorate(str)}; 
         println(str, len);
-    }}
-#line 10 "pure2-intro-example-hello-2022.cpp2"
+    }
 }
 
 [[nodiscard]] auto decorate(auto& thing) -> int{

regression-tests/test-results/pure2-intro-example-three-loops.cpp

@@ -52,10 +52,9 @@ auto decorate_and_print(auto& thing) -> void{
     } while ( cpp2::cmp_greater(*cpp2::assert_not_null(i),1) && [&]{ --*cpp2::assert_not_null(i) ; return true; }() );
 
     std::cout << "\n";
-    { auto&& cpp2_range = words; for ( auto& word : cpp2_range ) 
-        decorate_and_print(word);}
+    for ( auto& word : words ) 
+        decorate_and_print(word);
 
-#line 28 "pure2-intro-example-three-loops.cpp2"
     print(std::string{"end of program"});
 }
 

regression-tests/test-results/pure2-statement-scope-parameters.cpp

@@ -28,9 +28,9 @@ auto const& i = local_int;
 
     //  'in' (read-only) statement scope variable
 #line 6 "pure2-statement-scope-parameters.cpp2"
-    { auto const& cpp2_range = args; for ( auto const& arg : cpp2_range ) {
+    for ( auto const& arg : args ) {
         std::cout << i << "\n";     // prints 42
-    }}
+    }
 }
 {
 auto& i = local_int;

regression-tests/test-results/pure2-type-and-namespace-aliases.cpp

@@ -61,9 +61,8 @@ auto myfunc() -> void{
 
     auto const& v2 = std::move(v);
 
-    { auto const& cpp2_range = v2; for ( auto const& s : cpp2_range ) 
-        std::cout << cpp2::to_string(s) + "\n";}
-#line 24 "pure2-type-and-namespace-aliases.cpp2"
+    for ( auto const& s : v2 ) 
+        std::cout << cpp2::to_string(s) + "\n";
 }
 
 auto main() -> int{

regression-tests/test-results/version

@@ -1,9 +1,10 @@
 
-cppfront compiler v0.2.1   Build 8514:1707
+cppfront compiler v0.2.1   Build 8514:1724
 Copyright(c) Herb Sutter   All rights reserved
 
 SPDX-License-Identifier: CC-BY-NC-ND-4.0
   No commercial use
   No forks/derivatives
+FAQ: Why? Because this is a personal experiment at this time
 
 Absolutely no warranty - try at your own risk

source/build.info

@@ -1 +1 @@
-"8514:1707"
+"8514:1724"

source/cppfront.cpp

@@ -2129,16 +2129,11 @@ class cppfront
             //        but some major compilers seem to have random troubles with that;
             //        the workaround to avoid their bugs for now is to emit a { } block
             //        around the Cpp1 range-for and make the scope variable a normal local
-            if (n.for_with_in) {
-                printer.print_cpp2("{ auto const& cpp2_range = ", n.position());
-            }
-            else {
-                printer.print_cpp2("{ auto&& cpp2_range = ", n.position());
-            }
-            emit(*n.range);
-            printer.print_cpp2("; for ( ", n.position());
+            printer.print_cpp2("for ( ", n.position());
             emit(*n.parameter);
-            printer.print_cpp2(" : cpp2_range ) ", n.position());
+            printer.print_cpp2(" : ", n.position());
+            emit(*n.range);
+            printer.print_cpp2(" ) ", n.position());
             if (!labelname.empty()) {
                 printer.print_extra("{");
             }
@@ -2164,8 +2159,6 @@ class cppfront
                 printer.print_extra(" CPP2_CONTINUE_BREAK("+labelname+") }");
             }
 
-            printer.print_extra("}");
-
             in_non_rvalue_context.pop_back();
         }