Diagnose uninitialized uses of a variable within its own initializer.
This is basically the same idea as the warning on uninitialized uses of
fields within an initializer list. As such, it is on by default and
under -Wuninitialized.
Original patch by Richard Trieu, with some massaging from me on the
wording and grouping of the diagnostics.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@128376 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 55223ac..6e0bec2 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -871,6 +871,9 @@
"uninitialized reference member is here">;
def warn_field_is_uninit : Warning<"field is uninitialized when used here">,
InGroup<Uninitialized>;
+def warn_uninit_self_reference_in_init : Warning<
+ "variable %0 is uninitialized when used within its own initialization">,
+ InGroup<Uninitialized>;
def warn_uninit_var : Warning<"variable %0 is possibly uninitialized when used here">,
InGroup<Uninitialized>, DefaultIgnore;
def warn_maybe_uninit_var :
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 59b4f5f..7a1492a 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -25,6 +25,7 @@
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
+#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/CharUnits.h"
@@ -4664,6 +4665,46 @@
return true;
}
+namespace {
+ // Visits an initialization expression to see if OrigDecl is evaluated in
+ // its own initialization and throws a warning if it does.
+ class SelfReferenceChecker
+ : public EvaluatedExprVisitor<SelfReferenceChecker> {
+ Sema &S;
+ Decl *OrigDecl;
+
+ public:
+ typedef EvaluatedExprVisitor<SelfReferenceChecker> Inherited;
+
+ SelfReferenceChecker(Sema &S, Decl *OrigDecl) : Inherited(S.Context),
+ S(S), OrigDecl(OrigDecl) { }
+
+ void VisitExpr(Expr *E) {
+ if (isa<ObjCMessageExpr>(*E)) return;
+ Inherited::VisitExpr(E);
+ }
+
+ void VisitImplicitCastExpr(ImplicitCastExpr *E) {
+ CheckForSelfReference(E);
+ Inherited::VisitImplicitCastExpr(E);
+ }
+
+ void CheckForSelfReference(ImplicitCastExpr *E) {
+ if (E->getCastKind() != CK_LValueToRValue) return;
+ Expr* SubExpr = E->getSubExpr()->IgnoreParenImpCasts();
+ DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(SubExpr);
+ if (!DRE) return;
+ Decl* ReferenceDecl = DRE->getDecl();
+ if (OrigDecl != ReferenceDecl) return;
+ LookupResult Result(S, DRE->getNameInfo(), Sema::LookupOrdinaryName,
+ Sema::NotForRedeclaration);
+ S.Diag(SubExpr->getLocStart(), diag::warn_uninit_self_reference_in_init)
+ << Result.getLookupName() << OrigDecl->getLocation()
+ << SubExpr->getSourceRange();
+ }
+ };
+}
+
/// AddInitializerToDecl - Adds the initializer Init to the
/// declaration dcl. If DirectInit is true, this is C++ direct
/// initialization rather than copy initialization.
@@ -4674,6 +4715,8 @@
if (RealDecl == 0 || RealDecl->isInvalidDecl())
return;
+ SelfReferenceChecker(*this, RealDecl).VisitExpr(Init);
+
if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(RealDecl)) {
// With declarators parsed the way they are, the parser cannot
// distinguish between a normal initializer and a pure-specifier.
@@ -5231,7 +5274,7 @@
if (Decl *D = Group[i])
Decls.push_back(D);
- return BuildDeclaratorGroup(Decls.data(), Decls.size(),
+ return BuildDeclaratorGroup(Decls.data(), Decls.size(),
DS.getTypeSpecType() == DeclSpec::TST_auto);
}
diff --git a/test/PCH/pragma-diag-section.cpp b/test/PCH/pragma-diag-section.cpp
index 312f720..5b996bb 100644
--- a/test/PCH/pragma-diag-section.cpp
+++ b/test/PCH/pragma-diag-section.cpp
@@ -12,7 +12,10 @@
#pragma clang diagnostic ignored "-Wtautological-compare"
template <typename T>
struct TS {
- void m() { T b = b==b; }
+ void m() {
+ T a = 0;
+ T b = a==a;
+ }
};
#pragma clang diagnostic pop
diff --git a/test/PCH/pragma-diag.c b/test/PCH/pragma-diag.c
index c517103..b304c4b 100644
--- a/test/PCH/pragma-diag.c
+++ b/test/PCH/pragma-diag.c
@@ -13,7 +13,8 @@
#else
void f() {
- int b = b==b;
+ int a = 0;
+ int b = a==a;
}
#endif
diff --git a/test/PCH/rdar8852495.c b/test/PCH/rdar8852495.c
index 2d49e00..fb465a3 100644
--- a/test/PCH/rdar8852495.c
+++ b/test/PCH/rdar8852495.c
@@ -16,7 +16,8 @@
#else
int f() {
- int b = b==b;
+ int a;
+ int b = a==a;
unsigned x;
signed y;
return x == y;
diff --git a/test/Preprocessor/pragma_diagnostic_sections.cpp b/test/Preprocessor/pragma_diagnostic_sections.cpp
index 69436b0..b680fae 100644
--- a/test/Preprocessor/pragma_diagnostic_sections.cpp
+++ b/test/Preprocessor/pragma_diagnostic_sections.cpp
@@ -2,14 +2,14 @@
// rdar://8365684
struct S {
- void m1() { int b = b==b; } // expected-warning {{always evaluates to true}}
+ void m1() { int b; while (b==b); } // expected-warning {{always evaluates to true}}
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wtautological-compare"
- void m2() { int b = b==b; }
+ void m2() { int b; while (b==b); }
#pragma clang diagnostic pop
- void m3() { int b = b==b; } // expected-warning {{always evaluates to true}}
+ void m3() { int b; while (b==b); } // expected-warning {{always evaluates to true}}
};
//------------------------------------------------------------------------------
@@ -18,7 +18,7 @@
#pragma clang diagnostic ignored "-Wtautological-compare"
template <typename T>
struct TS {
- void m() { T b = b==b; }
+ void m() { T b; while (b==b); }
};
#pragma clang diagnostic pop