case-sensitivity inconsistency in quoted column aliases in FROM subselects

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POSTGRESQL BUG REPORT TEMPLATE
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Your name : Mike Hoolehan
Your email address : mike(at)sycamorehq(dot)com

System Configuration
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Architecture (example: Intel Pentium) : Intel Pentium

Operating System (example: Linux 2.0.26 ELF) : RH 7.2, Kernel 2.4.9-13

PostgreSQL version (example: PostgreSQL-7.1.3): PostgreSQL-7.1.3

Compiler used (example: gcc 2.95.2) : gcc 2.96 (rpm version)

Please enter a FULL description of your problem:
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if a quoted column alias in a FROM clause sub-select contains upper-case
chars, then that column cannot be later referenced without using quotes

Please describe a way to repeat the problem. Please try to provide a
concise reproducible example, if at all possible:
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SELECT * FROM (SELECT col1 as "Foo" from table1) AS innerQuery
WHERE Foo = 'whatever';
results in
"ERROR: Attribute 'foo' not found"
no matter what capitalization is used for "Foo" in the where clause
(i.e. foo='whatever', FOO='whatever', etc).
I assume this is a bug, since if the column is aliases as "foo" (with
quotes, all lowercase), then the column can later be referenced
without quotes with case-insensitivity.

If you know how this problem might be fixed, list the solution below:
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