Fix PR9624 by explicitly disabling uninitialized warnings for direct self-init:
int x = x;
GCC disables its warnings on this construct as a way of indicating that
the programmer intentionally wants the variable to be uninitialized.
Only the warning on the initializer is turned off in this iteration.
This makes the code a lot more ugly, but starts commenting the
surprising behavior here. This is a WIP, I want to refactor it
substantially for clarity, and to determine whether subsequent warnings
should be suppressed or not.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@128894 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index efb71ba..df73fc6 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -410,16 +410,6 @@
};
}
-static bool isSelfInit(ASTContext &Context,
- const VarDecl *VD, const DeclRefExpr *DR) {
- if (const Expr *E = VD->getInit()) {
- ContainsReference CR(Context, DR);
- CR.Visit(const_cast<Expr*>(E));
- return CR.doesContainReference();
- }
- return false;
-}
-
typedef std::pair<const Expr*, bool> UninitUse;
namespace {
@@ -473,17 +463,37 @@
for (UsesVec::iterator vi = vec->begin(), ve = vec->end(); vi != ve; ++vi)
{
const bool isAlwaysUninit = vi->second;
- bool showDefinition = true;
+ bool isSelfInit = false;
if (const DeclRefExpr *dr = dyn_cast<DeclRefExpr>(vi->first)) {
if (isAlwaysUninit) {
- if (isSelfInit(S.Context, vd, dr)) {
+ // Inspect the initializer of the variable declaration which is
+ // being referenced prior to its initialization. We emit
+ // specialized diagnostics for self-initialization, and we
+ // specifically avoid warning about self references which take the
+ // form of:
+ //
+ // int x = x;
+ //
+ // This is used to indicate to GCC that 'x' is intentionally left
+ // uninitialized. Proven code paths which access 'x' in
+ // an uninitialized state after this will still warn.
+ //
+ // TODO: Should we suppress maybe-uninitialized warnings for
+ // variables initialized in this way?
+ if (const Expr *E = vd->getInit()) {
+ if (dr == E->IgnoreParenImpCasts())
+ continue;
+
+ ContainsReference CR(S.Context, dr);
+ CR.Visit(const_cast<Expr*>(E));
+ isSelfInit = CR.doesContainReference();
+ }
+ if (isSelfInit) {
S.Diag(dr->getLocStart(),
diag::warn_uninit_self_reference_in_init)
<< vd->getDeclName() << vd->getLocation() << dr->getSourceRange();
- showDefinition = false;
- }
- else {
+ } else {
S.Diag(dr->getLocStart(), diag::warn_uninit_var)
<< vd->getDeclName() << dr->getSourceRange();
}
@@ -501,8 +511,9 @@
<< vd->getDeclName();
}
- // Report where the variable was declared.
- if (showDefinition)
+ // Report where the variable was declared when the use wasn't within
+ // the initializer of that declaration.
+ if (!isSelfInit)
S.Diag(vd->getLocStart(), diag::note_uninit_var_def)
<< vd->getDeclName();