Only inspect expressions for now

For `inspect` statements, we'll need to repeat the `if constexpr` rigamarole

Author: hsutter

source/lex.h

@@ -728,7 +728,7 @@ auto lex_line(
  //G 
  //G floating-point-literal:
  //G digit { ' | digit }* . digit { ' | digit }*
- //GTODO TODO: full grammar
+ //GTODO full grammar
  //G 
  else if (is_digit(line[i])) {
  auto j = 1;

source/parse.h

@@ -1949,7 +1949,7 @@ class parser
  // it doesn't destabilize any regression tests
  )
  {
- error("expression-statement does not end with semicolon");
+ error("expected ; at end of statement");
  return {};
  }
  if (curr().type() == lexeme::Semicolon) {
@@ -2267,6 +2267,14 @@ class parser
  return {};
  }
 
+ if (!is_expression) {
+ errors.emplace_back(
+ curr().position(),
+ "(temporary alpha limitation) cppfront is still learning 'inspect' - only inspect expressions are currently supported"
+ );
+ return {};
+ }
+
  auto n = std::make_unique<inspect_expression_node>();
  n->identifier = &curr();
  next();