Cleanup: Make PerfSymbolTable::attachDwfl more type safe

Replace `void* arg` by explicit `PerfUnwind::UnwindInfo *unwindInfo`
instead of casting the void to that type internally.

Change-Id: I64a716f7f89ae75e1b21470a927441f07beb70c6
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

2 files changed, 3 insertions, 4 deletions

diff --git a/app/perfsymboltable.cpp b/app/perfsymboltable.cpp
index 55efb16..ac8ae11 100644
--- a/app/perfsymboltable.cpp
+++ b/app/perfsymboltable.cpp
@@ -836,7 +836,7 @@ bool PerfSymbolTable::containsAddress(quint64 address) const
     return m_elfs.isAddressInRange(address);
 }
 
-Dwfl *PerfSymbolTable::attachDwfl(const Dwfl_Thread_Callbacks *callbacks, void *arg)
+Dwfl *PerfSymbolTable::attachDwfl(const Dwfl_Thread_Callbacks *callbacks, PerfUnwind::UnwindInfo *unwindInfo)
 {
     if (static_cast<pid_t>(m_pid) == dwfl_pid(m_dwfl))
         return m_dwfl; // Already attached, nothing to do
@@ -844,14 +844,13 @@ Dwfl *PerfSymbolTable::attachDwfl(const Dwfl_Thread_Callbacks *callbacks, void *
     // only attach state when we have the required information for stack unwinding
     // for normal symbol resolution and inline frame resolution this is not needed
     // most notably, this isn't needed for frame pointer callchains
-    PerfUnwind::UnwindInfo *unwindInfo = static_cast<PerfUnwind::UnwindInfo *>(arg);
     const auto sampleType = unwindInfo->sample->type();
     const auto hasSampleRegsUser = (sampleType & PerfEventAttributes::SAMPLE_REGS_USER);
     const auto hasSampleStackUser = (sampleType & PerfEventAttributes::SAMPLE_STACK_USER);
     if (!hasSampleRegsUser || !hasSampleStackUser)
         return nullptr;
 
-    if (!dwfl_attach_state(m_dwfl, m_firstElf.elf(), m_pid, callbacks, arg)) {
+    if (!dwfl_attach_state(m_dwfl, m_firstElf.elf(), m_pid, callbacks, unwindInfo)) {
         qWarning() << m_pid << "failed to attach state" << dwfl_errmsg(dwfl_errno());
         return nullptr;
     }
diff --git a/app/perfsymboltable.h b/app/perfsymboltable.h
index 66ba74e..0367560 100644
--- a/app/perfsymboltable.h
+++ b/app/perfsymboltable.h
@@ -72,7 +72,7 @@ public:
     void updatePerfMap();
     bool containsAddress(quint64 address) const;
 
-    Dwfl *attachDwfl(const Dwfl_Thread_Callbacks *callbacks, void *arg);
+    Dwfl *attachDwfl(const Dwfl_Thread_Callbacks *callbacks, PerfUnwind::UnwindInfo *unwindInfo);
     void clearCache();
     bool cacheIsDirty() const { return m_cacheIsDirty; }