compilerplugins: try to make these work with icecream

There are some problems here, this should fix one of them: the
getFilename function returns "<stdin>" for spelling locations, because
the input to clang is sort of preprocessed via -frewrite-includes if
icecream is used and the file is built on a remote host (whereas it's
apparently not preprocessed if the file is compiled locally by icecream).

Using getPresumedLoc() uses the #line directives in the preprocessed
input, which avoids the problem but is more expensive, so try to use it
only when necessary.

The getFileEntry(getMainFileID())->getName() pattern will also result
in "<stdin>", but fortunately icecream passes -main-file-name,
which oddly enough isn't used by the SourceManager's spelling locations,
but is available separately via CodeGenOptions.

This builds everything successfully with clang version 6.0.0:
ICECC_PREFERRED_HOST=myremote make check gb_SUPPRESS_TESTS=t

Change-Id: Ic121511683e5302d7b9d85186c8b9c4a5443fa1b
Reviewed-on: https://gerrit.libreoffice.org/54993
Tested-by: Jenkins
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>

1 files changed, 1 insertions, 3 deletions

diff --git a/compilerplugins/clang/unusedvariablemore.cxx b/compilerplugins/clang/unusedvariablemore.cxx
index ead91586c460..fa2ff366052b 100644
--- a/compilerplugins/clang/unusedvariablemore.cxx
+++ b/compilerplugins/clang/unusedvariablemore.cxx
@@ -63,9 +63,7 @@ static bool startswith(const std::string& rStr, const char* pSubStr)
 
 void UnusedVariableMore::run()
 {
-    std::string fn(compiler.getSourceManager()
-                       .getFileEntryForID(compiler.getSourceManager().getMainFileID())
-                       ->getName());
+    std::string fn(handler.getMainFileName());
     loplugin::normalizeDotDotInFilePath(fn);
 
     // ignore QA folders