Bug #877: numbers are no longer recognized as smallints

Denis N. Stepanov (D(dot)N(dot)Stepanov(at)inp(dot)nsk(dot)su) reports a bug with a severity of 2
The lower the number the more severe it is.

Short Description
numbers are no longer recognized as smallints

Long Description
I have bunch of functions (doesn't matter of which language) which take parameters as 'smallint's. I used to pass parameters into them as is, i.e. plain numbers without explicit typecasting. But while trying to upgrade from PostgreSQL 7.2.3 to 7.3.1 I discovered that this no longer works. All function calls now fail convincing me to add explicit typecasts. I believe this is incorrect since, say, 1 is a correct notation for smallint type and it should NOT require explicit typecase in each and every place. I tried to find the grounds of such change in 7.3.1 docs but did not succeed. Please let me know whether this is a bug or I just miss something important here.

Sample Code
testdasdb=# create function test(smallint) returns integer as 'select 0' language 'sql';
CREATE FUNCTION
testdasdb=# select test(1);
ERROR: Function test(integer) does not exist
Unable to identify a function that satisfies the given argument types
You may need to add explicit typecasts

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