c++: use YY_NOEXCEPT where it helps

[Akim Demaille]

commit 3fc3ef658e855565d2fa83f0a05a0369edbede1f
Author: Akim Demaille <akim.demaille@gmail.com>
Date:   Sat Sep 18 08:02:41 2021 +0200

    c++: use YY_NOEXCEPT where it helps
    
    Suggested by Don Macpherson.
    <https://github.com/akimd/bison/issues/80>
    
    * data/skeletons/c++.m4, data/skeletons/glr2.cc,
    * data/skeletons/lalr1.cc, data/skeletons/stack.hh: Use YY_NOEXCEPT
    where it helps constructors.

diff --git a/data/skeletons/c++.m4 b/data/skeletons/c++.m4
index 42f6404e..2ae8423a 100644
--- a/data/skeletons/c++.m4
+++ b/data/skeletons/c++.m4
@@ -308,7 +308,7 @@ m4_define([b4_symbol_type_define],
       typedef Base super_type;
 
       /// Default constructor.
-      basic_symbol ()
+      basic_symbol () YY_NOEXCEPT
         : value ()]b4_locations_if([
         , location ()])[
       {}
@@ -437,16 +437,22 @@ m4_define([b4_symbol_type_define],
     /// Type access provider for token (enum) based symbols.
     struct by_kind
     {
+      /// The symbol kind as needed by the constructor.
+      typedef token_kind_type kind_type;
+
       /// Default constructor.
-      by_kind ();
+      by_kind () YY_NOEXCEPT;
 
 #if 201103L <= YY_CPLUSPLUS
       /// Move constructor.
-      by_kind (by_kind&& that);
+      by_kind (by_kind&& that) YY_NOEXCEPT;
 #endif
 
       /// Copy constructor.
-      by_kind (const by_kind& that);
+      by_kind (const by_kind& that) YY_NOEXCEPT;
+
+      /// Constructor from (external) token numbers.
+      by_kind (kind_type t) YY_NOEXCEPT;
 
 ]b4_glr2_cc_if([[
       /// Copy assignment.
@@ -456,12 +462,6 @@ m4_define([b4_symbol_type_define],
       by_kind& operator= (by_kind&& that);
 ]])[
 
-      /// The symbol kind as needed by the constructor.
-      typedef token_kind_type kind_type;
-
-      /// Constructor from (external) token numbers.
-      by_kind (kind_type t);
-
       /// Record that this symbol is empty.
       void clear () YY_NOEXCEPT;
 
@@ -490,7 +490,7 @@ m4_define([b4_symbol_type_define],
       typedef basic_symbol<by_kind> super_type;
 
       /// Empty symbol.
-      symbol_type () {}
+      symbol_type () YY_NOEXCEPT {}
 
       /// Constructor for valueless symbols, and symbols from each type.
 ]b4_type_foreach([_b4_symbol_constructor_define])dnl
@@ -564,23 +564,23 @@ m4_define([b4_public_types_define],
   }
 
   // by_kind.
-  ]b4_inline([$1])b4_parser_class[::by_kind::by_kind ()
+  ]b4_inline([$1])b4_parser_class[::by_kind::by_kind () YY_NOEXCEPT
     : kind_ (]b4_symbol(empty, kind)[)
   {}
 
 #if 201103L <= YY_CPLUSPLUS
-  ]b4_inline([$1])b4_parser_class[::by_kind::by_kind (by_kind&& that)
+  ]b4_inline([$1])b4_parser_class[::by_kind::by_kind (by_kind&& that) 
YY_NOEXCEPT
     : kind_ (that.kind_)
   {
     that.clear ();
   }
 #endif
 
-  ]b4_inline([$1])b4_parser_class[::by_kind::by_kind (const by_kind& that)
+  ]b4_inline([$1])b4_parser_class[::by_kind::by_kind (const by_kind& that) 
YY_NOEXCEPT
     : kind_ (that.kind_)
   {}
 
-  ]b4_inline([$1])b4_parser_class[::by_kind::by_kind (token_kind_type t)
+  ]b4_inline([$1])b4_parser_class[::by_kind::by_kind (token_kind_type t) 
YY_NOEXCEPT
     : kind_ (yytranslate_ (t))
   {}
 
@@ -643,7 +643,7 @@ m4_define([b4_token_constructor_define], [])
 # sometimes in the cc file.
 m4_define([b4_yytranslate_define],
 [  b4_inline([$1])b4_parser_class[::symbol_kind_type
-  ]b4_parser_class[::yytranslate_ (int t)
+  ]b4_parser_class[::yytranslate_ (int t) YY_NOEXCEPT
   {
 ]b4_api_token_raw_if(
 [[    return static_cast<symbol_kind_type> (t);]],
diff --git a/data/skeletons/glr2.cc b/data/skeletons/glr2.cc
index 8b06c37a..757d68d4 100644
--- a/data/skeletons/glr2.cc
+++ b/data/skeletons/glr2.cc
@@ -348,7 +348,7 @@ m4_define([b4_shared_declarations],
     /// Convert a scanner token kind \a t to a symbol kind.
     /// In theory \a t should be a token_kind_type, but character literals
     /// are valid, yet not members of the token_kind_type enum.
-    static symbol_kind_type yytranslate_ (int t);
+    static symbol_kind_type yytranslate_ (int t) YY_NOEXCEPT;
 
 ]b4_parse_error_bmatch(
 [simple],
@@ -3136,13 +3136,13 @@ b4_dollar_popdef])[]dnl
     }
 
     static bool
-    yy_is_shift_action (int yyaction)
+    yy_is_shift_action (int yyaction) YY_NOEXCEPT
     {
       return 0 < yyaction;
     }
 
     static bool
-    yy_is_error_action (int yyaction)
+    yy_is_error_action (int yyaction) YY_NOEXCEPT
     {
       return yyaction == 0;
     }
diff --git a/data/skeletons/lalr1.cc b/data/skeletons/lalr1.cc
index 11fcf923..7cb69d3d 100644
--- a/data/skeletons/lalr1.cc
+++ b/data/skeletons/lalr1.cc
@@ -325,11 +325,11 @@ m4_define([b4_shared_declarations],
 
     /// Whether the given \c yypact_ value indicates a defaulted state.
     /// \param yyvalue   the value to check
-    static bool yy_pact_value_is_default_ (int yyvalue);
+    static bool yy_pact_value_is_default_ (int yyvalue) YY_NOEXCEPT;
 
     /// Whether the given \c yytable_ value indicates a syntax error.
     /// \param yyvalue   the value to check
-    static bool yy_table_value_is_error_ (int yyvalue);
+    static bool yy_table_value_is_error_ (int yyvalue) YY_NOEXCEPT;
 
     static const ]b4_int_type(b4_pact_ninf, b4_pact_ninf)[ yypact_ninf_;
     static const ]b4_int_type(b4_table_ninf, b4_table_ninf)[ yytable_ninf_;
@@ -337,7 +337,7 @@ m4_define([b4_shared_declarations],
     /// Convert a scanner token kind \a t to a symbol kind.
     /// In theory \a t should be a token_kind_type, but character literals
     /// are valid, yet not members of the token_kind_type enum.
-    static symbol_kind_type yytranslate_ (int t);
+    static symbol_kind_type yytranslate_ (int t) YY_NOEXCEPT;
 
 ]b4_parse_error_bmatch(
 [simple],
@@ -474,7 +474,7 @@ m4_define([b4_shared_declarations],
     void yypush_ (const char* m, state_type s, YY_MOVE_REF (symbol_type) sym);
 
     /// Pop \a n symbols from the stack.
-    void yypop_ (int n = 1);
+    void yypop_ (int n = 1) YY_NOEXCEPT;
 
     /// Constants.
     enum
@@ -779,7 +779,7 @@ m4_if(b4_prefix, [yy], [],
   }
 
   void
-  ]b4_parser_class[::yypop_ (int n)
+  ]b4_parser_class[::yypop_ (int n) YY_NOEXCEPT
   {
     yystack_.pop (n);
   }
@@ -822,13 +822,13 @@ m4_if(b4_prefix, [yy], [],
   }
 
   bool
-  ]b4_parser_class[::yy_pact_value_is_default_ (int yyvalue)
+  ]b4_parser_class[::yy_pact_value_is_default_ (int yyvalue) YY_NOEXCEPT
   {
     return yyvalue == yypact_ninf_;
   }
 
   bool
-  ]b4_parser_class[::yy_table_value_is_error_ (int yyvalue)
+  ]b4_parser_class[::yy_table_value_is_error_ (int yyvalue) YY_NOEXCEPT
   {
     return yyvalue == yytable_ninf_;
   }
diff --git a/data/skeletons/stack.hh b/data/skeletons/stack.hh
index bd5756c1..98913258 100644
--- a/data/skeletons/stack.hh
+++ b/data/skeletons/stack.hh
@@ -37,7 +37,7 @@ m4_define([b4_stack_define],
       typedef typename S::size_type size_type;
       typedef typename std::ptrdiff_t index_type;
 
-      stack (size_type n = 200)
+      stack (size_type n = 200) YY_NOEXCEPT
         : seq_ (n)
       {}
 
@@ -116,7 +116,7 @@ m4_define([b4_stack_define],
       class slice
       {
       public:
-        slice (const stack& stack, index_type range)
+        slice (const stack& stack, index_type range) YY_NOEXCEPT
           : stack_ (stack)
           , range_ (range)
         {}