clang incorrectly rejects references to earlier parameters in a prototype

[efriedma-quic]

Bugzilla Link	2046
Resolution	FIXED
Resolved on	Mar 12, 2010 00:56
Version	unspecified
OS	Linux

Extended Description

Testcase:
int aa(int b, int x[sizeof b]) {}

This is perfectly legal C90 and C99 code, but clang claims the b is undeclared.

[lattner]

Simpler testcase: void foo(int i, int A[i]) {}

[lattner]

*** Bug llvm/llvm-bugzilla-archive#2195 has been marked as a duplicate of this bug. ***

[lattner]

This is actually incredibly ugly. Currently clang doesn't make param decls for arguments when parsing an argument list: it only creates them when parsing a function body. Instead, it just evaluates the type of the argument. This appears to be sufficient except for cases like this.

This issue brings up "interesting" (aka PITA) lifetime issues as well. For example, in this case:

int (*v)(int b, int x[sizeof b]) {}

we now need to keep the decl for 'b' around, because it is referenced by the type of 'x'. This implies that we need to create and keep around decls for all arguments in prototypes unless we are extremely clever. This will punish normal cases like:

void exit(int status)

by making us keep a decl for status around.

[lattner]

Doug fixed this, patch here:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20080407/005079.html

[lattner]

mentioned in issue llvm/llvm-bugzilla-archive#2195