Remove some alloca uses

A few spots (mostly in the parsers) use alloca to ensure that a string
is terminated before passing it to a printf-like function (mostly
'error').  However, this isn't needed as the "%.*s" format can be used
instead.

This patch makes this change.

In one spot the alloca is dead code and is simply removed.

Regression tested on x86-64 Fedora 38.

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

gdb/c-exp.y

@@ -2784,13 +2784,8 @@ lex_one_token (struct parser_state *par_state, bool *is_quoted_name)
 	toktype = parse_number (par_state, tokstart, p - tokstart,
 				got_dot | got_e | got_p, &yylval);
 	if (toktype == ERROR)
-	  {
-	    char *err_copy = (char *) alloca (p - tokstart + 1);
-
-	    memcpy (err_copy, tokstart, p - tokstart);
-	    err_copy[p - tokstart] = 0;
-	    error (_("Invalid number \"%s\"."), err_copy);
-	  }
+	  error (_("Invalid number \"%.*s\"."), (int) (p - tokstart),
+		 tokstart);
 	pstate->lexptr = p;
 	return toktype;
       }
@@ -3434,14 +3429,8 @@ c_print_token (FILE *file, int type, YYSTYPE value)
 
     case CHAR:
     case STRING:
-      {
-	char *copy = (char *) alloca (value.tsval.length + 1);
-
-	memcpy (copy, value.tsval.ptr, value.tsval.length);
-	copy[value.tsval.length] = '\0';
-
-	parser_fprintf (file, "tsval<type=%d, %s>", value.tsval.type, copy);
-      }
+      parser_fprintf (file, "tsval<type=%d, %.*s>", value.tsval.type,
+		      value.tsval.length, val.tsval.ptr);
       break;
 
     case NSSTRING:

gdb/cp-name-parser.y

@@ -1702,10 +1702,6 @@ yylex (YYSTYPE *lvalp, cpname_state *state)
 				       lvalp);
 	if (toktype == ERROR)
 	  {
-	    char *err_copy = (char *) alloca (p - tokstart + 1);
-
-	    memcpy (err_copy, tokstart, p - tokstart);
-	    err_copy[p - tokstart] = 0;
 	    yyerror (state, _("invalid number"));
 	    return ERROR;
 	  }

gdb/cp-support.c

@@ -2214,19 +2214,11 @@ test_cp_remove_params ()
 static void
 first_component_command (const char *arg, int from_tty)
 {
-  int len;  
-  char *prefix; 
-
   if (!arg)
     return;
 
-  len = cp_find_first_component (arg);
-  prefix = (char *) alloca (len + 1);
-
-  memcpy (prefix, arg, len);
-  prefix[len] = '\0';
-
-  gdb_printf ("%s\n", prefix);
+  int len = cp_find_first_component (arg);
+  gdb_printf ("%.*s\n", len, arg);
 }
 
 /* Implement "info vtbl".  */

gdb/d-exp.y

@@ -1154,13 +1154,8 @@ lex_one_token (struct parser_state *par_state)
 	toktype = parse_number (par_state, tokstart, p - tokstart,
 				got_dot|got_e, &yylval);
 	if (toktype == ERROR)
-	  {
-	    char *err_copy = (char *) alloca (p - tokstart + 1);
-
-	    memcpy (err_copy, tokstart, p - tokstart);
-	    err_copy[p - tokstart] = 0;
-	    error (_("Invalid number \"%s\"."), err_copy);
-	  }
+	  error (_("Invalid number \"%.*s\"."), (int) (p - tokstart),
+		 tokstart);
 	pstate->lexptr = p;
 	return toktype;
       }

gdb/f-exp.y

@@ -1557,13 +1557,8 @@ yylex (void)
 				got_dot|got_e|got_d,
 				&yylval);
 	if (toktype == ERROR)
-	  {
-	    char *err_copy = (char *) alloca (p - tokstart + 1);
-	    
-	    memcpy (err_copy, tokstart, p - tokstart);
-	    err_copy[p - tokstart] = 0;
-	    error (_("Invalid number \"%s\"."), err_copy);
-	  }
+	  error (_("Invalid number \"%.*s\"."), (int) (p - tokstart),
+		 tokstart);
 	pstate->lexptr = p;
 	return toktype;
       }

gdb/go-exp.y

@@ -1103,13 +1103,8 @@ lex_one_token (struct parser_state *par_state)
 	toktype = parse_number (par_state, tokstart, p - tokstart,
 				got_dot|got_e, &yylval);
 	if (toktype == ERROR)
-	  {
-	    char *err_copy = (char *) alloca (p - tokstart + 1);
-
-	    memcpy (err_copy, tokstart, p - tokstart);
-	    err_copy[p - tokstart] = 0;
-	    error (_("Invalid number \"%s\"."), err_copy);
-	  }
+	  error (_("Invalid number \"%.*s\"."), (int) (p - tokstart),
+		 tokstart);
 	par_state->lexptr = p;
 	return toktype;
       }

gdb/m2-exp.y

@@ -869,13 +869,8 @@ yylex (void)
 	}
 	toktype = parse_number (p - tokstart);
 	if (toktype == ERROR)
-	  {
-	    char *err_copy = (char *) alloca (p - tokstart + 1);
-
-	    memcpy (err_copy, tokstart, p - tokstart);
-	    err_copy[p - tokstart] = 0;
-	    error (_("Invalid number \"%s\"."), err_copy);
-	  }
+	  error (_("Invalid number \"%.*s\"."), (int) (p - tokstart),
+		 tokstart);
 	pstate->lexptr = p;
 	return toktype;
     }

gdb/p-exp.y

@@ -1239,13 +1239,8 @@ yylex (void)
 	toktype = parse_number (pstate, tokstart,
 				p - tokstart, got_dot | got_e, &yylval);
 	if (toktype == ERROR)
-	  {
-	    char *err_copy = (char *) alloca (p - tokstart + 1);
-
-	    memcpy (err_copy, tokstart, p - tokstart);
-	    err_copy[p - tokstart] = 0;
-	    error (_("Invalid number \"%s\"."), err_copy);
-	  }
+	  error (_("Invalid number \"%.*s\"."), (int) (p - tokstart),
+		 tokstart);
 	pstate->lexptr = p;
 	return toktype;
       }