make oncevar plugin ignore methods with #ifdef-ery

Change-Id: I8a9cf2c4b81b95bf654f7e90306328d72e3d3408
Reviewed-on: https://gerrit.libreoffice.org/40280
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 48 insertions, 0 deletions

diff --git a/compilerplugins/clang/plugin.cxx b/compilerplugins/clang/plugin.cxx
index 66e22d507818..5bfdc4ed3a83 100644
--- a/compilerplugins/clang/plugin.cxx
+++ b/compilerplugins/clang/plugin.cxx
@@ -273,6 +273,54 @@ bool Plugin::isUnitTestMode()
     return PluginHandler::isUnitTestMode();
 }
 
+bool Plugin::containsPreprocessingConditionalInclusion(SourceRange range)
+{
+    auto const begin = compiler.getSourceManager().getExpansionLoc(
+        range.getBegin());
+    auto const end = compiler.getSourceManager().getExpansionLoc(
+        range.getEnd());
+    assert(begin.isFileID() && end.isFileID());
+    if (!(begin == end
+          || compiler.getSourceManager().isBeforeInTranslationUnit(
+              begin, end)))
+    {
+        // Conservatively assume "yes" if lexing fails (e.g., due to
+        // macros):
+        return true;
+    }
+    auto hash = false;
+    for (auto loc = begin;;) {
+        Token tok;
+        if (Lexer::getRawToken(
+                loc, tok, compiler.getSourceManager(),
+                compiler.getLangOpts(), true))
+        {
+            // Conservatively assume "yes" if lexing fails (e.g., due to
+            // macros):
+            return true;
+        }
+        if (hash && tok.is(tok::raw_identifier)) {
+            auto const id = tok.getRawIdentifier();
+            if (id == "if" || id == "ifdef" || id == "ifndef"
+                || id == "elif" || id == "else" || id == "endif")
+            {
+                return true;
+            }
+        }
+        if (loc == range.getEnd()) {
+            break;
+        }
+        hash = tok.is(tok::hash) && tok.isAtStartOfLine();
+        loc = loc.getLocWithOffset(
+            std::max<unsigned>(
+                Lexer::MeasureTokenLength(
+                    loc, compiler.getSourceManager(),
+                    compiler.getLangOpts()),
+                1));
+    }
+    return false;
+}
+
 RewritePlugin::RewritePlugin( const InstantiationData& data )
     : Plugin( data )
     , rewriter( data.rewriter )