Local object aliases should also be constexpr

See hsutter#731

Author: hsutter

regression-tests/pure2-type-and-namespace-aliases.cpp2

@@ -17,8 +17,7 @@ N3: namespace == ::std::literals;
 myfunc: () = {
     v: N1::pmr_vec<myclass::str> = ("xyzzy", "plugh");
 
-    v2 :== v;
-
+    (v2 := v)
     for v2 do (s)
         std::cout << "(s)$\n";
 }

regression-tests/test-results/pure2-print.cpp

@@ -170,8 +170,8 @@ requires ((std::is_convertible_v<CPP2_TYPEOF(x), int> && ...))
 
         using type_alias = std::array<int,10>;
 
-        cpp2::i8 const& object_alias_1 = 42;
-        auto const& object_alias_2 = 42;
+        cpp2::i8 constexpr object_alias_1 = 42;
+        auto constexpr object_alias_2 = 42;
 
 #line 75 "pure2-print.cpp2"
         ::outer::mytype var {}; 

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

@@ -43,7 +43,7 @@ namespace N3 = ::std::literals;
 auto myfunc() -> void;
 
 
-#line 26 "pure2-type-and-namespace-aliases.cpp2"
+#line 25 "pure2-type-and-namespace-aliases.cpp2"
 auto main() -> int;
 
 
@@ -58,18 +58,21 @@ namespace N {
 #line 17 "pure2-type-and-namespace-aliases.cpp2"
 auto myfunc() -> void{
     N1::pmr_vec<myclass::str> v {"xyzzy", "plugh"}; 
+{
+auto const& v2 = std::move(v);
 
-    auto const& v2 = std::move(v);
-
+#line 21 "pure2-type-and-namespace-aliases.cpp2"
     for ( auto const& s : v2 ) 
         std::cout << cpp2::to_string(s) + "\n";
 }
+#line 23 "pure2-type-and-namespace-aliases.cpp2"
+}
 
 auto main() -> int{
     using view = std::string_view;
     namespace N4 = std::literals;
 
-    auto const& myfunc2 = myfunc;
+    auto constexpr myfunc2 = myfunc;
     myfunc2();
 }
 

regression-tests/test-results/version

@@ -1,5 +1,5 @@
 
-cppfront compiler v0.2.1   Build 8A09:0922
+cppfront compiler v0.2.1   Build 8A09:1000
 Copyright(c) Herb Sutter   All rights reserved
 
 SPDX-License-Identifier: CC-BY-NC-ND-4.0

source/build.info

@@ -1 +1 @@
-"8A09:0922"
+"8A09:1000"

source/cppfront.cpp

@@ -5192,7 +5192,7 @@ class cppfront
                     {
                         auto intro = std::string{};
                         if (n.parent_is_function()) {
-                            intro = "const&";
+                            intro = "constexpr";
                         }
                         else if (n.parent_is_namespace()) {
                             intro = "inline constexpr";