In an almost resounding silence that is a measure of how things have changed in the past generation, Congress has passed and sent to President Carter a bill that would have the effect of wiping out a major Cold War-era restriction on visits to this country by Communist labor leaders.

With an elegant bit of legislative wordsmanship, the bill sent to Carter Wednesday would, for practical purposes, repeal a provision of the McCarran-Walter Act of 1952 that has given AFL-CIO chief George Meany a virtual veto over visits by labor officials from Communist nations.

The act provides that Communists, Marxists, anrchists and persons associated with groups of those persuasions may not receive visas unless the Secretary of State recommends a special waiver.

In practice, most people who fall into those categories have had little trouble getting into this country. Between 1972 and 1976, more than 99.9 per cent of waiver applications were approved, said a congressional source.

But Communist labor leaders have been another matter. Meany and the AFL-CIO strongly oppose communism, and last year, in a case involving a Soviet trade union delegation, the State Department acknowledged they have a virtual veto over visits by Communist labor officials.

Labor is not happy to see its veto power removed. "The concept that an official who they say is the leader of a trade union should be able to come into the U.S. to us is ridiculous," said Alan Zack, an AFL-CIO spokesman.

Referring to a Soviet labor leader, Zack said, "He is obviously an overseer, he is not a union leader, not an elected representative of the people. He is an appointed part of the mechanism for the suppression of workers' rights.

"If the government of the Soviet Union wanted him to come to the U.S. in his capacity as a government official, (that) is one thing, and we have no objection. But to say that he is coming in as a representative of a union is to make a mockery of the right of people to choose their leaders."

Nevertheless, there was little strong lobbying against the new bill by labor or anyone else, say congressional sources. Nor was there an effort by the bill's backers to publicize its effects.

"We kept very quiet indeed about it," said one. "That's why the bill passed."

The change in the law was not made by addressing the McCarran-Walter Act directly. Instead, it is affected by language in the State Department authorization bill for next year, stating that the Secretary of State "should" recommend a waiver unless it would threaten U.S. security.

By not confronting the act, said supporters of the bill, they avoided harmful publicity, retained the Secretary's latitude to keep out terrorists and deprived Eurocommunists of the "cachet" of being accepted or rejected for visits on an individual basis.