gdb: merge error handling from different expression parsers

Many (all?) of the expression parsers implement yyerror to handle
parser errors, and all of these functions are basically identical.

This commit adds a new parser_state::parse_error() function, which
implements the common error handling code, this function can then be
called from all the different yyerror functions.

The benefit of this is that (in a future commit) I can improve the
error output, and all the expression parsers will benefit.

This commit is pure refactoring though, and so, there should be no
user visible changes after this commit.

Approved-By: John Baldwin <jhb@FreeBSD.org>

gdb/ada-exp.y

@@ -1212,7 +1212,7 @@ ada_parse (struct parser_state *par_state)
 static void
 yyerror (const char *msg)
 {
-  error (_("Error in expression, near `%s'."), pstate->lexptr);
+  pstate->parse_error (msg);
 }
 
 /* Emit expression to access an instance of SYM, in block BLOCK (if

gdb/c-exp.y

@@ -3482,8 +3482,5 @@ c_print_token (FILE *file, int type, YYSTYPE value)
 static void
 yyerror (const char *msg)
 {
-  if (pstate->prev_lexptr)
-    pstate->lexptr = pstate->prev_lexptr;
-
-  error (_("A %s in expression, near `%s'."), msg, pstate->lexptr);
+  pstate->parse_error (msg);
 }

gdb/d-exp.y

@@ -1631,9 +1631,6 @@ d_parse (struct parser_state *par_state)
 static void
 yyerror (const char *msg)
 {
-  if (pstate->prev_lexptr)
-    pstate->lexptr = pstate->prev_lexptr;
-
-  error (_("A %s in expression, near `%s'."), msg, pstate->lexptr);
+  pstate->parse_error (msg);
 }
 

gdb/f-exp.y

@@ -1736,8 +1736,5 @@ f_language::parser (struct parser_state *par_state) const
 static void
 yyerror (const char *msg)
 {
-  if (pstate->prev_lexptr)
-    pstate->lexptr = pstate->prev_lexptr;
-
-  error (_("A %s in expression, near `%s'."), msg, pstate->lexptr);
+  pstate->parse_error (msg);
 }

gdb/go-exp.y

@@ -1545,8 +1545,5 @@ go_language::parser (struct parser_state *par_state) const
 static void
 yyerror (const char *msg)
 {
-  if (pstate->prev_lexptr)
-    pstate->lexptr = pstate->prev_lexptr;
-
-  error (_("A %s in expression, near `%s'."), msg, pstate->lexptr);
+  pstate->parse_error (msg);
 }

gdb/m2-exp.y

@@ -1006,8 +1006,5 @@ m2_language::parser (struct parser_state *par_state) const
 static void
 yyerror (const char *msg)
 {
-  if (pstate->prev_lexptr)
-    pstate->lexptr = pstate->prev_lexptr;
-
-  error (_("A %s in expression, near `%s'."), msg, pstate->lexptr);
+  pstate->parse_error (msg);
 }

gdb/p-exp.y

@@ -1660,8 +1660,5 @@ pascal_language::parser (struct parser_state *par_state) const
 static void
 yyerror (const char *msg)
 {
-  if (pstate->prev_lexptr)
-    pstate->lexptr = pstate->prev_lexptr;
-
-  error (_("A %s in expression, near `%s'."), msg, pstate->lexptr);
+  pstate->parse_error (msg);
 }

gdb/parse.c

@@ -244,6 +244,17 @@ parser_state::push_dollar (struct stoken str)
     (create_internalvar (copy.c_str () + 1));
 }
 
+/* See parser-defs.h.  */
+
+void
+parser_state::parse_error (const char *msg)
+{
+  if (this->prev_lexptr)
+    this->lexptr = this->prev_lexptr;
+
+  error (_("A %s in expression, near `%s'."), msg, this->lexptr);
+}
+
 
 
 const char *

gdb/parser-defs.h

@@ -262,6 +262,11 @@ struct parser_state : public expr_builder
     push (expr::make_operation<T> (std::move (lhs), std::move (rhs)));
   }
 
+  /* Function called from the various parsers' yyerror functions to throw
+     an error.  The error will include a message identifying the location
+     of the error within the current expression.  */
+  void parse_error (const char *msg);
+
   /* If this is nonzero, this block is used as the lexical context for
      symbol names.  */