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Manman Ren authored
With PCH+Module, sometimes compiler gives a hard error:
Module file ‘<some-file path>.pcm' is out of date and needs to be rebuilt

This happens when we have a pch importing a module and the module gets
overwritten by another compiler instance after we build the pch (one example is
that both compiler instances hash to the same pcm file but use different
diagnostic options). When we try to load the pch later on, the compiler notices
that the imported module is out of date (modification date, size do not match)
but it can't handle this out of date pcm (i.e it does not know how to rebuild
the pch).

This commit introduces a new command line option so for PCH + module, we can
turn on this option and if two compiler instances only differ in diagnostic
options, the latter instance will not invalidate the original pcm.

rdar://26675801
Differential Revision: http://reviews.llvm.org/D22773


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@276769 91177308-0d34-0410-b5e6-96231b3b80d8
cefd5475
History
//===----------------------------------------------------------------------===//
// C Language Family Front-end
//===----------------------------------------------------------------------===//

Welcome to Clang.  This is a compiler front-end for the C family of languages
(C, C++, Objective-C, and Objective-C++) which is built as part of the LLVM
compiler infrastructure project.

Unlike many other compiler frontends, Clang is useful for a number of things
beyond just compiling code: we intend for Clang to be host to a number of
different source-level tools.  One example of this is the Clang Static Analyzer.

If you're interested in more (including how to build Clang) it is best to read
the relevant web sites.  Here are some pointers:

Information on Clang:              http://clang.llvm.org/
Building and using Clang:          http://clang.llvm.org/get_started.html
Clang Static Analyzer:             http://clang-analyzer.llvm.org/
Information on the LLVM project:   http://llvm.org/

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  http://lists.llvm.org/mailman/listinfo/cfe-dev

If you find a bug in Clang, please file it in the LLVM bug tracker:
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