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Bug 37998

Summary: Unclear documentation of -fno-common
Product: gcc Reporter: Daniel Macks <dmacks>
Component: cAssignee: Not yet assigned to anyone <unassigned>
Severity: normal CC: gcc-bugs, sandra
Priority: P3 Keywords: documentation
Version: 4.3.2   
Target Milestone: ---   
Host: Target:
Build: Known to work:
Known to fail: Last reconfirmed: 2009-05-17 13:42:32

Description Daniel Macks 2008-11-02 19:10:46 UTC
The gcc.1 manpage states:

> In C, allocate even uninitialized global variables in the data sec-
> tion of the object file, rather than generating them as common
> blocks.  This has the effect that if the same variable is declared
> (without "extern") in two different compilations, you will get an
> error when you link them.

That description is confusing because it's unclear which of the two opposite situations in the first sentence is the antecedent of the "This" in the second sentence. Alternative and clearer wordings for second sentence could be:

> If the same variable is declared (without "extern") in two
> different compilations and is allocated in the common blocks, you
> will get an error when you link them due to multiple allocations of
> the same global symbol.
Comment 1 sandra 2016-11-10 23:57:02 UTC
Author: sandra
Date: Thu Nov 10 23:56:30 2016
New Revision: 242062

2016-11-10  Sandra Loosemore  <>

	PR c/37998

	* doc/invoke.texi (Code Gen Options) [-fno-common]: Use correct
	terminology.  Expand to remove ambiguity.

Comment 2 sandra 2016-11-11 00:27:25 UTC
Fixed on trunk.