Extend loplugin:external to warn about enums

To mitigate the dangers of silently breaking ADL when moving enums into unnamed
namespaces (see the commit message of 206b5b2661be37efdff3c6aedb6f248c4636be79
"New loplugin:external"), note all functions that are affected.  (The plan is to
extend loplugin:external further to also warn about classes and class templates,
and the code to identify affected functions already takes that into account, so
some parts of that code are not actually relevant for enums.)

But it appears that none of the functions that are actually affected by the
changes in this commit relied on being found through ADL, so no adaptions were
necessary for them.

(clang::DeclContext::collectAllContexts is non-const, which recursively means
that External's Visit... functions must take non-const Decl*.  Which required
compilerplugins/clang/sharedvisitor/analyzer.cxx to be generalized to support
such Visit... functions with non-const Decl* parameters.)

Change-Id: Ia215291402bf850d43defdab3cff4db5b270d1bd
Reviewed-on: https://gerrit.libreoffice.org/83001
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 7 insertions, 0 deletions

diff --git a/comphelper/source/container/enumerablemap.cxx b/comphelper/source/container/enumerablemap.cxx
index f003fe0e02ee..bee5d03963b2 100644
--- a/comphelper/source/container/enumerablemap.cxx
+++ b/comphelper/source/container/enumerablemap.cxx
@@ -194,12 +194,14 @@ namespace comphelper
         MapData             m_aData;
     };
 
+    namespace {
 
     enum EnumerationType
     {
         eKeys, eValues, eBoth
     };
 
+    }
 
     class MapEnumerator final
     {
diff --git a/comphelper/source/misc/syntaxhighlight.cxx b/comphelper/source/misc/syntaxhighlight.cxx
index b3f62a70365b..60ecc7b97c94 100644
--- a/comphelper/source/misc/syntaxhighlight.cxx
+++ b/comphelper/source/misc/syntaxhighlight.cxx
@@ -26,6 +26,8 @@
 #include <comphelper/syntaxhighlight.hxx>
 #include <o3tl/typed_flags_set.hxx>
 
+namespace {
+
 // Flags for character properties
 enum class CharFlags {
     StartIdentifier   = 0x0001,
@@ -39,6 +41,9 @@ enum class CharFlags {
     Space             = 0x0100,
     EOL               = 0x0200
 };
+
+}
+
 namespace o3tl {
     template<> struct typed_flags<CharFlags> : is_typed_flags<CharFlags, 0x03ff> {};
 }