Convert compiler_services to Cpp2

Add helpful diagnostic for trying to use Cpp1 `->` syntax for dereference.

Restrict `assert_not_null` to raw pointers, not STL iterators, which the comment already noted were not guaranteed to work. In the Microsoft STL under `_ITERATOR_DEBUG_LEVEL=2`, comparing a `set` or `map` iterator with a default-constructed iterator of the same type is flagged by [this test](https://github.com/microsoft/STL/blob/a62109595b6d89e08172fdf4beb75a2670fe0cc9/stl/inc/xtree#L230) as erroneously comparing objects that refer into different containers.

Author: hsutter

include/cpp2util.h

@@ -386,8 +386,10 @@ auto assert_not_null(auto&& p CPP2_SOURCE_LOCATION_PARAM_WITH_DEFAULT) -> declty
 {
     //  NOTE: This "!= T{}" test may or may not work for STL iterators. The standard
     //        doesn't guarantee that using == and != will reliably report whether an
-    //        STL iterator has the default-constructed value
-    Null.expects(p != CPP2_TYPEOF(p){}, "dynamic null dereference attempt detected" CPP2_SOURCE_LOCATION_ARG);
+    //        STL iterator has the default-constructed value. So use it only for raw *...
+    if constexpr (std::is_pointer_v<CPP2_TYPEOF(p)>) {
+        Null.expects(p != CPP2_TYPEOF(p){}, "dynamic null dereference attempt detected" CPP2_SOURCE_LOCATION_ARG);
+    }
     return CPP2_FORWARD(p);
 }
 

regression-tests/test-results/clang-12/run-tests-clang-12.sh

@@ -22,3 +22,4 @@ done
 rm -f *.obj *.exp *.lib
 printf "\nDone: %s .cpp tests compiled\n" "$count"
 printf "\n      %s .cpp executables generated and run\n" "$exe_count"
+echo "$(date +"%T")"

regression-tests/test-results/gcc-10/run-tests-gcc-10.sh

@@ -22,3 +22,4 @@ done
 rm -f *.obj *.exp *.lib
 printf "\nDone: %s .cpp tests compiled\n" "$count"
 printf "\n      %s .cpp executables generated and run\n" "$exe_count"
+echo "$(date +"%T")"

regression-tests/test-results/msvc-2022/run-tests-msvc-2022.bat

@@ -23,4 +23,5 @@ del *.obj *.exp *.lib
 echo.
 echo Done: %count% .cpp tests compiled
 echo.
-echo.      %exe_count% executables generated and run
+echo.      %exe_count% executables generated and run
+echo %TIME%

regression-tests/test-results/run-tests.bat

@@ -28,4 +28,5 @@ echo.      %err_count% error test cases (should not generate .cpp)
 echo.      %total_count% total
 if %total_count% NEQ %count% (
     echo.      *** MISMATCH: should equal total tests run
-)
+)
+echo %TIME%

regression-tests/test-results/version

@@ -1,5 +1,5 @@
 
-cppfront compiler v0.2.1   Build 8521:1217
+cppfront compiler v0.2.1   Build 8522:0446
 Copyright(c) Herb Sutter   All rights reserved
 
 SPDX-License-Identifier: CC-BY-NC-ND-4.0

source/build.info

@@ -1 +1 @@
-"8521:1217"
+"8522:0446"

source/cppfront.cpp

@@ -4481,7 +4481,7 @@ class cppfront
 
                 auto found_explicit_init = false;
                 auto found_default_init  = false;
-                auto stmt_pos = source_position{};
+                auto stmt_pos = n.position();
 
                 auto initializer = std::string{};
 

source/parse.h

@@ -4184,17 +4184,27 @@ class parser
         }
     }
 
-    //G  expression:                // eliminated condition: - use expression:
+    //G  expression:                // eliminated 'condition:' - just use 'expression:'
     //G     assignment-expression
     //GTODO    try expression
     //G
-    auto expression(bool allow_angle_operators = true)
+    auto expression(bool allow_angle_operators = true, bool check_arrow = true)
         -> std::unique_ptr<expression_node>
     {
         auto n = std::make_unique<expression_node>();
         if (!(n->expr = assignment_expression(allow_angle_operators))) {
             return {};
         }
+
+        if (
+            check_arrow
+            && curr().type() == lexeme::Arrow
+            )
+        {
+            error("'->' is not Cpp2 deference syntax - write '*.' instead");
+            return {};
+        }
+
         return n;
     }
 
@@ -5073,7 +5083,7 @@ class parser
             next();
         }
 
-        if (auto e = expression()) {
+        if (auto e = expression(true, false)) {
             n->expression = std::move(e);
         }
         else {