Compile Cppfront cleanly using MSVC /W4, GCC /Wall, Clang /Wall

Cppfront now compiles cleanly using these command lines:
- `cl cppfront.cpp -std:c++20 -EHsc -W4`
- `g++-10 -std=c++20 cppfront.cpp -Wall`
- `clang++-12 -std=c++20 cppfront.cpp -Wall`

This exposed (and this commit fixes) one bug: Cppfront should reject `move` and `forward` only if preceded by `std::`

Note: I don't currently see a benefit to trying to compile cleanly under -Wextra:
- GCC-10 -Wextra generates 3 -Wmissing-field-initializer that seem spurious, and 1 -Wimplicit-fallthrough that is intentional and commented (I looked again and if there's a bug I'm not seeing it)
- Clang-12 -Wextra generates two -Wmissing-field-initializer warnings that don't seem useful

Author: hsutter

source/common.h

@@ -11,6 +11,12 @@
 // THE SOFTWARE.
 
 
+#ifdef _MSC_VER
+#pragma warning(disable: 4456)
+#endif
+//#include "../include/cpp2util.h"
+
+
 //===========================================================================
 //  Common types
 //===========================================================================
@@ -396,7 +402,7 @@ class cmdline_processor
             }
             print("  -");
             auto n = flag.name.substr(0, flag.unique_prefix);
-            if (flag.unique_prefix < flag.name.length()) {
+            if (flag.unique_prefix < std::ssize(flag.name)) {
                 n += "[";
                 n += flag.name.substr(flag.unique_prefix);
                 n += "]";

source/cppfront.cpp

@@ -190,7 +190,7 @@ class positional_printer
         //  Update curr_pos by finding how many line breaks s contained,
         //  and where the last one was which determines our current colno
         auto last_newline = std::string::npos;  // the last newline we found in the string
-        auto newline_pos  = 0;                  // the current newline we found in the string
+        auto newline_pos  = std::size_t(0);     // the current newline we found in the string
         while ((newline_pos = s.find('\n', newline_pos)) != std::string::npos)
         {
             //  For each line break we find, reset pad and inc current lineno
@@ -1638,7 +1638,7 @@ class cppfront
                 }
                 ++mynum;
             }
-            assert (mynum < n.cap_grp->size() && "could not find this postfix-expression in capture group");
+            assert (mynum < std::ssize(*n.cap_grp) && "could not find this postfix-expression in capture group");
             //  And then emit that capture number
             captured_part += "_" + std::to_string(mynum);
         }
@@ -1714,7 +1714,6 @@ class cppfront
         auto prefix            = std::vector<text_with_pos>{};
         auto suffix            = std::vector<text_with_pos>{};
 
-        auto emitted_n         = false;
         auto last_was_prefixed = false;
         auto saw_dollar        = false;
 

source/lex.h

@@ -295,7 +295,7 @@ auto lex_line(
     //
     auto peek = [&](int num) {  return (i+num < std::ssize(line)) ? line[i+num] : '\0';  };
 
-    auto store = [&](int16_t num, lexeme type)
+    auto store = [&](auto num, lexeme type)
     {
         tokens.push_back({
             &line[i],
@@ -445,7 +445,7 @@ auto lex_line(
         if (std::regex_search(&line[i], m, keys)) {
             assert (m.position(0) == 0);
             //  If we matched and what's next is EOL or a non-identifier char, we matched!
-            if (i+m[0].length() == line.length() ||             // EOL
+            if (i+m[0].length() == std::ssize(line) ||          // EOL
                 !is_identifier_continue(line[i+m[0].length()])  // non-identifier char
                 )
             {

source/load.h

@@ -302,8 +302,6 @@ auto process_cpp2_line(
     std::string const&  line,
     bool&               in_comment,
     std::vector<int>&   brace_depth,
-    bool&               found_semi,
-    bool&               found_openbrace,
     lineno_t            lineno,
     std::vector<error>& errors
 )
@@ -481,15 +479,11 @@ class source
                     }
 
                     //  Find the end of the definition:
-                    auto found_semi = false;
-                    auto found_openbrace = false;
                     while (
                         !process_cpp2_line(
                             lines.back().text,
                             in_comment,
                             brace_depth,
-                            found_semi,
-                            found_openbrace,
                             std::ssize(lines)-1,
                             errors
                         )

source/parse.h

@@ -882,7 +882,7 @@ struct declaration_node
 
     token const* pointer_declarator = nullptr;
 
-    enum active { function, object };
+    enum active : std::uint8_t { function, object };
     std::variant<
         std::unique_ptr<function_type_node>,
         std::unique_ptr<type_id_node>
@@ -1267,7 +1267,7 @@ class parser
         errors.emplace_back( curr().position(), m );
     }
 
-    auto error(std::string const& msg, bool include_curr_token = true) const -> void
+    auto error(std::string const& msg, bool = true) const -> void
     {
         error(msg.c_str());
     }
@@ -1638,7 +1638,7 @@ class parser
         }
         else {
             return binary_expression<relational_expression_node> (
-                [](token const& t){ return false; },
+                [](token const&){ return false; },
                 [this]{ return compare_expression(); }
             );
         }
@@ -1950,7 +1950,7 @@ class parser
                 return {};
             }
             assert (term.id->identifier);
-            if (first_time_through_loop && term.scope_op->type() == lexeme::Scope) {
+            if (first_time_through_loop && first_uid_was_std && term.scope_op->type() == lexeme::Scope) {
                 if (*term.id->identifier == "move") {
                     error("std::move is not needed in Cpp2 - use 'move' parameters/arguments instead", false);
                     return {};
@@ -2839,7 +2839,7 @@ class parser
     //G     : type-id-opt = statement
     //G     : type-id
     //G
-    auto unnamed_declaration(source_position pos, bool semicolon_required = true, bool captures_allowed = false) -> std::unique_ptr<declaration_node>
+    auto unnamed_declaration(source_position start, bool semicolon_required = true, bool captures_allowed = false) -> std::unique_ptr<declaration_node>
     {
         auto deduced_type = false;
 
@@ -2850,16 +2850,13 @@ class parser
         next();
 
         auto n = std::make_unique<declaration_node>();
-        n->pos = pos;
+        n->pos = start;
         auto guard =
             captures_allowed
             ? make_unique<capture_groups_stack_guard>(this, &n->captures)
             : std::unique_ptr<capture_groups_stack_guard>()
             ;
 
-        //  Remember current position, because we need to look ahead
-        auto start_pos = pos;
-
         //  Next is an an optional type
 
         //  It could be a function type, declaring a function
@@ -3043,7 +3040,7 @@ class parse_tree_printer : printing_visitor
         o << pre(indent) << n.to_string() << "\n";
     }
 
-    auto start(expression_node const& n, int indent) -> void
+    auto start(expression_node const&, int indent) -> void
     {
         o << pre(indent) << "expression\n";
         //  If we are in an expression-list
@@ -3067,7 +3064,7 @@ class parse_tree_printer : printing_visitor
         o << pre(indent) << "expression-list\n";
     }
 
-    auto end(expression_list_node const& n, int indent) -> void
+    auto end(expression_list_node const& n, int) -> void
     {
         //  If we're ending an expression list node, our pointer should be
         //  pointing to one past the end of the expressions
@@ -3081,58 +3078,58 @@ class parse_tree_printer : printing_visitor
         current_expression_list_term.pop_back();
     }
 
-    auto start(primary_expression_node const& n, int indent) -> void
+    auto start(primary_expression_node const&, int indent) -> void
     {
         o << pre(indent) << "primary-expression\n";
     }
 
-    auto start(prefix_expression_node const& n, int indent) -> void
+    auto start(prefix_expression_node const&, int indent) -> void
     {
         o << pre(indent) << "prefix-expression\n";
     }
 
     template<String Name, typename Term>
-    auto start(binary_expression_node<Name, Term> const& n, int indent) -> void
+    auto start(binary_expression_node<Name, Term> const&, int indent) -> void
     {
         o << pre(indent) << Name.value << "-expression\n";
     }
 
-    auto start(expression_statement_node const& n, int indent) -> void
+    auto start(expression_statement_node const&, int indent) -> void
     {
         o << pre(indent) << "expression-statement\n";
     }
 
-    auto start(postfix_expression_node const& n, int indent) -> void
+    auto start(postfix_expression_node const&, int indent) -> void
     {
         o << pre(indent) << "postfix-expression\n";
     }
 
-    auto start(unqualified_id_node const& n, int indent) -> void
+    auto start(unqualified_id_node const&, int indent) -> void
     {
         o << pre(indent) << "unqualified-id\n";
     }
 
-    auto start(qualified_id_node const& n, int indent) -> void
+    auto start(qualified_id_node const&, int indent) -> void
     {
         o << pre(indent) << "qualified-id\n";
     }
 
-    auto start(type_id_node const& n, int indent) -> void
+    auto start(type_id_node const&, int indent) -> void
     {
         o << pre(indent) << "type-id\n";
     }
 
-    auto start(id_expression_node const& n, int indent) -> void
+    auto start(id_expression_node const&, int indent) -> void
     {
         o << pre(indent) << "id-expression\n";
     }
 
-    auto start(statement_node const& n, int indent) -> void
+    auto start(statement_node const&, int indent) -> void
     {
         o << pre(indent) << "statement\n";
     }
 
-    auto start(compound_statement_node const& n, int indent) -> void
+    auto start(compound_statement_node const&, int indent) -> void
     {
         o << pre(indent) << "compound-statement\n";
     }
@@ -3143,7 +3140,7 @@ class parse_tree_printer : printing_visitor
         o << pre(indent+1) << "is_constexpr: " << as<std::string>(n.is_constexpr) << "\n";
     }
 
-    auto start(alternative_node const& n, int indent) -> void
+    auto start(alternative_node const&, int indent) -> void
     {
         o << pre(indent) << "alternative\n";
     }
@@ -3154,7 +3151,7 @@ class parse_tree_printer : printing_visitor
         o << pre(indent+1) << "is_constexpr: " << as<std::string>(n.is_constexpr) << "\n";
     }
 
-    auto start(return_statement_node const& n, int indent) -> void
+    auto start(return_statement_node const&, int indent) -> void
     {
         o << pre(indent) << "return-statement\n";
     }
@@ -3185,7 +3182,7 @@ class parse_tree_printer : printing_visitor
         o << pre(indent+1) << "throws: " << as<std::string>(n.throws) << "\n";
     }
 
-    auto start(function_returns_tag const& n, int indent) -> void
+    auto start(function_returns_tag const&, int indent) -> void
     {
         o << pre(indent) << "function returns\n";
     }
@@ -3226,12 +3223,12 @@ class parse_tree_printer : printing_visitor
         assert( n.declaration );
     }
 
-    auto start(parameter_declaration_list_node const& n, int indent) -> void
+    auto start(parameter_declaration_list_node const&, int indent) -> void
     {
         o << pre(indent) << "parameter-declaration-list\n";
     }
 
-    auto start(translation_unit_node const& n, int indent) -> void
+    auto start(translation_unit_node const&, int indent) -> void
     {
         o << pre(indent) << "translation-unit\n";
     }
@@ -3241,7 +3238,7 @@ class parse_tree_printer : printing_visitor
         o << pre(indent) << "UNRECOGNIZED -- FIXME\n";
     }
 
-    auto end(auto const&, int indent) -> void
+    auto end(auto const&, int) -> void
     {
         //  Ignore other node types
     }
@@ -3272,7 +3269,7 @@ class adjust_remaining_token_columns_on_this_line_visitor
         , col_offset{offset}
     { }
 
-    auto start(token& n, int indent) -> void
+    auto start(token& n, int) -> void
     {
         if (n.position().lineno == line_to_adjust_pos.lineno &&
             n.position().colno >= line_to_adjust_pos.colno
@@ -3282,12 +3279,12 @@ class adjust_remaining_token_columns_on_this_line_visitor
         }
     }
 
-    auto start(auto const&, int indent) -> void
+    auto start(auto const&, int) -> void
     {
         //  Ignore other node types
     }
 
-    auto end(auto const&, int indent) -> void
+    auto end(auto const&, int) -> void
     {
         //  Ignore other node types
     }

source/sema.h

@@ -792,7 +792,7 @@ class sema
         inside_out_parameter = {};
     }
 
-    auto start(expression_node const& n, int indent) -> void
+    auto start(expression_node const&, int) -> void
     {
         is_out_expression = false;
 
@@ -805,7 +805,7 @@ class sema
         }
     }
 
-    auto start(expression_list_node const& n, int indent) -> void
+    auto start(expression_list_node const& n, int) -> void
     {
         //  We're going to use the pointer as an iterator
         if (!n.expressions.empty()) {
@@ -816,7 +816,7 @@ class sema
         }
     }
 
-    auto end(expression_list_node const& n, int indent) -> void
+    auto end(expression_list_node const&, int) -> void
     {
         //  Unlike debug_print, here we don't assert that we visited all the
         //  expressions in the list because visiting them all is not always needed
@@ -911,7 +911,7 @@ class sema
         ++scope_depth;
     }
 
-    auto end(selection_statement_node const& n, int) -> void
+    auto end(selection_statement_node const&, int) -> void
     {
         symbols.emplace_back( scope_depth, selection_sym{ false, active_selections.back() } );
         active_selections.pop_back();
@@ -955,12 +955,12 @@ class sema
         }
     }
 
-    auto start(auto const&, int indent) -> void
+    auto start(auto const&, int) -> void
     {
         //  Ignore other node types
     }
 
-    auto end(auto const&, int indent) -> void
+    auto end(auto const&, int) -> void
     {
         //  Ignore other node types
     }