Update test filename and messages for #419

Author: hsutter

regression-tests/pure2-cpp1-prefix-expression.cpp2 renamed to regression-tests/pure2-cpp1-prefix-expression-error.cpp2

@@ -1,4 +1,4 @@
-main: () = 
+main: () =
 {
     v := 1;
     p := &v;

regression-tests/test-results/pure2-cpp1-prefix-expression-error.cpp2.output

@@ -0,0 +1,3 @@
+pure2-cpp1-prefix-expression-error.cpp2...
+pure2-cpp1-prefix-expression-error.cpp2(4,10): error: prefix '&var' address-of is not valid Cpp2; use postfix 'var&' instead
+

regression-tests/test-results/pure2-cpp1-prefix-expression.cpp2.output

@@ -1,5 +1,5 @@
 
-cppfront compiler v0.2.1   Build 8520:1316
+cppfront compiler v0.2.1   Build 8520:1326
 Copyright(c) Herb Sutter   All rights reserved
 
 SPDX-License-Identifier: CC-BY-NC-ND-4.0

regression-tests/test-results/version

@@ -1 +1 @@
-"8520:1316"
+"8520:1326"

source/build.info

@@ -3854,15 +3854,15 @@ class parser
         switch (curr().type())
         {
         break; case lexeme::PlusPlus:
-            error("only postfix 'var++' increment is supported, not '++var'", false);
+            error("prefix '++var' is not valid Cpp2; use postfix 'var++' instead", false);
         break; case lexeme::MinusMinus:
-            error("only postfix 'var--' decrement is supported, not '--var'", false);
+            error("prefix '--var' is not valid Cpp2; use postfix 'var--' instead", false);
         break; case lexeme::Multiply:
-            error("use postfix 'ptr*' to dereference, not '*ptr'", false);
+            error("prefix '*ptr' dereference is not valid Cpp2; use postfix 'ptr*' instead", false);
         break; case lexeme::Ampersand:
-            error("use postfix 'var&' for address, not '&var'", false);
+            error("prefix '&var' address-of is not valid Cpp2; use postfix 'var&' instead", false);
         break; case lexeme::Tilde:
-            error("use postfix 'var~' for bitwise complement, not '~var'", false);
+            error("prefix '~var' is not valid Cpp2; use postfix 'var~' instead", false);
         break; default: ;
         }
         return {};