*** a/src/interfaces/libpq/fe-connect.c
--- b/src/interfaces/libpq/fe-connect.c
***************
*** 297,302 **** static PQconninfoOption *conninfo_parse(const char *conninfo,
--- 297,304 ----
  static PQconninfoOption *conninfo_array_parse(const char *const * keywords,
  					 const char *const * values, PQExpBuffer errorMessage,
  					 bool use_defaults, int expand_dbname);
+ static bool conninfo_fill_defaults(PQconninfoOption *options,
+ 			   PQExpBuffer errorMessage);
  static char *conninfo_getval(PQconninfoOption *connOptions,
  				const char *keyword);
  static void defaultNoticeReceiver(void *arg, const PGresult *res);
***************
*** 836,842 **** PQconndefaults(void)
  	initPQExpBuffer(&errorBuf);
  	if (PQExpBufferDataBroken(errorBuf))
  		return NULL;			/* out of memory already :-( */
! 	connOptions = conninfo_parse("", &errorBuf, true);
  	termPQExpBuffer(&errorBuf);
  	return connOptions;
  }
--- 838,860 ----
  	initPQExpBuffer(&errorBuf);
  	if (PQExpBufferDataBroken(errorBuf))
  		return NULL;			/* out of memory already :-( */
! 
! 	/* Make a working copy of PQconninfoOptions */
! 	connOptions = malloc(sizeof(PQconninfoOptions));
! 	if (connOptions == NULL)
! 	{
! 		printfPQExpBuffer(&errorBuf,
! 						  libpq_gettext("out of memory\n"));
! 		return NULL;
! 	}
! 	memcpy(connOptions, PQconninfoOptions, sizeof(PQconninfoOptions));
! 
! 	if (!conninfo_fill_defaults(connOptions, &errorBuf))
! 	{
! 		PQconninfoFree(connOptions);
! 		connOptions = NULL;
! 	}
! 
  	termPQExpBuffer(&errorBuf);
  	return connOptions;
  }
***************
*** 4002,4008 **** conninfo_parse(const char *conninfo, PQExpBuffer errorMessage,
  	char	   *pname;
  	char	   *pval;
  	char	   *buf;
- 	char	   *tmp;
  	char	   *cp;
  	char	   *cp2;
  	PQconninfoOption *options;
--- 4020,4025 ----
***************
*** 4170,4245 **** conninfo_parse(const char *conninfo, PQExpBuffer errorMessage,
  	free(buf);
  
  	/*
! 	 * Stop here if caller doesn't want defaults filled in.
! 	 */
! 	if (!use_defaults)
! 		return options;
! 
! 	/*
! 	 * If there's a service spec, use it to obtain any not-explicitly-given
! 	 * parameters.
  	 */
! 	if (parseServiceInfo(options, errorMessage))
  	{
  		PQconninfoFree(options);
  		return NULL;
  	}
  
- 	/*
- 	 * Get the fallback resources for parameters not specified in the conninfo
- 	 * string nor the service.
- 	 */
- 	for (option = options; option->keyword != NULL; option++)
- 	{
- 		if (option->val != NULL)
- 			continue;			/* Value was in conninfo or service */
- 
- 		/*
- 		 * Try to get the environment variable fallback
- 		 */
- 		if (option->envvar != NULL)
- 		{
- 			if ((tmp = getenv(option->envvar)) != NULL)
- 			{
- 				option->val = strdup(tmp);
- 				if (!option->val)
- 				{
- 					printfPQExpBuffer(errorMessage,
- 									  libpq_gettext("out of memory\n"));
- 					PQconninfoFree(options);
- 					return NULL;
- 				}
- 				continue;
- 			}
- 		}
- 
- 		/*
- 		 * No environment variable specified or this one isn't set - try
- 		 * compiled in
- 		 */
- 		if (option->compiled != NULL)
- 		{
- 			option->val = strdup(option->compiled);
- 			if (!option->val)
- 			{
- 				printfPQExpBuffer(errorMessage,
- 								  libpq_gettext("out of memory\n"));
- 				PQconninfoFree(options);
- 				return NULL;
- 			}
- 			continue;
- 		}
- 
- 		/*
- 		 * Special handling for user
- 		 */
- 		if (strcmp(option->keyword, "user") == 0)
- 		{
- 			option->val = pg_fe_getauthname(errorMessage);
- 			continue;
- 		}
- 	}
- 
  	return options;
  }
  
--- 4187,4200 ----
  	free(buf);
  
  	/*
! 	 * Fill in defaults if the caller wants that.
  	 */
! 	if (use_defaults && !conninfo_fill_defaults(options, errorMessage))
  	{
  		PQconninfoFree(options);
  		return NULL;
  	}
  
  	return options;
  }
  
***************
*** 4262,4268 **** conninfo_array_parse(const char *const * keywords, const char *const * values,
  					 PQExpBuffer errorMessage, bool use_defaults,
  					 int expand_dbname)
  {
- 	char	   *tmp;
  	PQconninfoOption *options;
  	PQconninfoOption *str_options = NULL;
  	PQconninfoOption *option;
--- 4217,4222 ----
***************
*** 4386,4405 **** conninfo_array_parse(const char *const * keywords, const char *const * values,
  	PQconninfoFree(str_options);
  
  	/*
! 	 * Stop here if caller doesn't want defaults filled in.
  	 */
! 	if (!use_defaults)
! 		return options;
  
  	/*
  	 * If there's a service spec, use it to obtain any not-explicitly-given
  	 * parameters.
  	 */
  	if (parseServiceInfo(options, errorMessage))
! 	{
! 		PQconninfoFree(options);
! 		return NULL;
! 	}
  
  	/*
  	 * Get the fallback resources for parameters not specified in the conninfo
--- 4340,4377 ----
  	PQconninfoFree(str_options);
  
  	/*
! 	 * Fill in defaults if the caller wants that.
  	 */
! 	if (use_defaults && !conninfo_fill_defaults(options, errorMessage))
! 	{
! 		PQconninfoFree(options);
! 		return NULL;
! 	}
! 
! 	return options;
! }
! 
! /*
!  * Fills the connection options array with the default values for unspecified
!  * options.
!  *
!  * Defaults are supplied from a service file, environment variables, etc.
!  *
!  * Returns TRUE if successful, FALSE otherwise, while filling in errorMessage.
!  */
! static bool
! conninfo_fill_defaults(PQconninfoOption *options,
! 					   PQExpBuffer errorMessage)
! {
! 	PQconninfoOption *option;
! 	char *tmp;
  
  	/*
  	 * If there's a service spec, use it to obtain any not-explicitly-given
  	 * parameters.
  	 */
  	if (parseServiceInfo(options, errorMessage))
! 		return false;
  
  	/*
  	 * Get the fallback resources for parameters not specified in the conninfo
***************
*** 4422,4429 **** conninfo_array_parse(const char *const * keywords, const char *const * values,
  				{
  					printfPQExpBuffer(errorMessage,
  									  libpq_gettext("out of memory\n"));
! 					PQconninfoFree(options);
! 					return NULL;
  				}
  				continue;
  			}
--- 4394,4400 ----
  				{
  					printfPQExpBuffer(errorMessage,
  									  libpq_gettext("out of memory\n"));
! 					return false;
  				}
  				continue;
  			}
***************
*** 4440,4447 **** conninfo_array_parse(const char *const * keywords, const char *const * values,
  			{
  				printfPQExpBuffer(errorMessage,
  								  libpq_gettext("out of memory\n"));
! 				PQconninfoFree(options);
! 				return NULL;
  			}
  			continue;
  		}
--- 4411,4417 ----
  			{
  				printfPQExpBuffer(errorMessage,
  								  libpq_gettext("out of memory\n"));
! 				return false;
  			}
  			continue;
  		}
***************
*** 4456,4462 **** conninfo_array_parse(const char *const * keywords, const char *const * values,
  		}
  	}
  
! 	return options;
  }
  
  static char *
--- 4426,4432 ----
  		}
  	}
  
! 	return true;
  }
  
  static char *