rtrieu created this revision.
Improve some diagnostics around self-initialization. The uninitialized checker
does not warn on self-initialization, but does warn later if the variable is
used. GCC also has a -Winit-self which will enable a -Wuninitialized warning
for self-initialized. -Winit-self is active in -Wall
There's also the matter of the variable being const. GCC -Wuninitialized will
warn on a const self-initialized with or without -Winit-self.
This patch will make it so that const self-initialization is always warned on
under -Wuninitialized. Since Clang does not use warning flags to control other
warnings, -Winit-self will be a new warning group for non-const
self-initialized. -Winit-self will also be in -Wall via -Wmost.
// GCC - warn with -Wuninitialized and -Winit-self
// Clang - no warning
// Clang with patch - warn with -Winit-self
void f1() {
int x = x;
}
// GCC - warn with -Wuninitialized
// Clang - no warning
// Clang with patch - warn with -Wuninitialized
void f2() {
const int x = x;
}
https://reviews.llvm.org/D52218
Files:
include/clang/Basic/DiagnosticGroups.td
include/clang/Basic/DiagnosticSemaKinds.td
lib/Sema/AnalysisBasedWarnings.cpp
lib/Sema/SemaDecl.cpp
test/SemaCXX/uninitialized.cpp
Index: test/SemaCXX/uninitialized.cpp
===================================================================
--- test/SemaCXX/uninitialized.cpp
+++ test/SemaCXX/uninitialized.cpp
@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -fsyntax-only -Wall -Wuninitialized -Wno-unused-value -Wno-unused-lambda-capture -std=c++1z -verify %s
+// RUN: %clang_cc1 -fsyntax-only -Wuninitialized -Wno-unused -std=c++1z -verify %s
+// RUN: %clang_cc1 -fsyntax-only -Wall -Wno-unused -Wno-init-self -std=c++1z -verify %s
// definitions for std::move
namespace std {
@@ -1432,7 +1433,7 @@
void array_capture(bool b) {
const char fname[] = "array_capture";
if (b) {
- int unused; // expected-warning {{unused variable}}
+ int unused;
} else {
[fname]{};
}
@@ -1447,3 +1448,15 @@
switch (int n; (n == k || k > 5)) {} // expected-warning {{uninitialized}} expected-note {{initialize}} expected-warning {{boolean}}
}
+
+namespace const_self_init {
+const int a = a; // no-warning for global
+
+void const_init() {
+ const int a = a; // expected-warning {{variable 'a' is uninitialized when used within its own initialization}}
+
+ const int b = b; // expected-warning {{variable 'b' is uninitialized when used within its own initialization}}
+ int c = b;
+}
+
+}
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -11111,6 +11111,19 @@
Init = Result.getAs<Expr>();
}
+ if (!VDecl->getType().isConstQualified()) {
+ if (auto *SubExpr = dyn_cast<ImplicitCastExpr>(Init->IgnoreParens())) {
+ if (SubExpr->getCastKind() == CK_LValueToRValue) {
+ if (auto *DRE = dyn_cast<DeclRefExpr>(SubExpr->getSubExpr())) {
+ if (DRE->getDecl() == VDecl) {
+ Diag(VDecl->getLocation(), diag::warn_uninit_self_init)
+ << VDecl << VDecl->getSourceRange() << DRE->getSourceRange();
+ }
+ }
+ }
+ }
+ }
+
// Check for self-references within variable initializers.
// Variables declared within a function/method body (except for references)
// are handled by a dataflow analysis.
Index: lib/Sema/AnalysisBasedWarnings.cpp
===================================================================
--- lib/Sema/AnalysisBasedWarnings.cpp
+++ lib/Sema/AnalysisBasedWarnings.cpp
@@ -977,7 +977,8 @@
// uninitialized. Proven code paths which access 'x' in
// an uninitialized state after this will still warn.
if (const Expr *Initializer = VD->getInit()) {
- if (!alwaysReportSelfInit && DRE == Initializer->IgnoreParenImpCasts())
+ if (!VD->getType().isConstQualified() && !alwaysReportSelfInit &&
+ DRE == Initializer->IgnoreParenImpCasts())
return false;
ContainsReference CR(S.Context, DRE);
@@ -1518,10 +1519,17 @@
UsesVec *vec = V.getPointer();
bool hasSelfInit = V.getInt();
- // Specially handle the case where we have uses of an uninitialized
- // variable, but the root cause is an idiomatic self-init. We want
- // to report the diagnostic at the self-init since that is the root cause.
- if (!vec->empty() && hasSelfInit && hasAlwaysUninitializedUse(vec))
+ if (hasSelfInit && vd->getType().isConstQualified()) {
+ // Handle "const int a = a;"
+ DiagnoseUninitializedUse(S, vd,
+ UninitUse(vd->getInit()->IgnoreParenCasts(),
+ /* isAlwaysUninit */ true),
+ /* alwaysReportSelfInit */ true);
+ } else if (!vec->empty() && hasSelfInit && hasAlwaysUninitializedUse(vec))
+ // Specially handle the case where we have uses of an uninitialized
+ // variable, but the root cause is an idiomatic self-init. We want
+ // to report the diagnostic at the self-init since that is the root
+ // cause.
DiagnoseUninitializedUse(S, vd,
UninitUse(vd->getInit()->IgnoreParenCasts(),
/* isAlwaysUninit */ true),
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -1907,6 +1907,8 @@
def warn_uninit_self_reference_in_init : Warning<
"variable %0 is uninitialized when used within its own initialization">,
InGroup<Uninitialized>;
+def warn_uninit_self_init : Warning<"variable %0 is initialized with itself">,
+ InGroup<InitSelf>, DefaultIgnore;
def warn_uninit_self_reference_in_reference_init : Warning<
"reference %0 is not yet bound to a value when used within its own"
" initialization">,
Index: include/clang/Basic/DiagnosticGroups.td
===================================================================
--- include/clang/Basic/DiagnosticGroups.td
+++ include/clang/Basic/DiagnosticGroups.td
@@ -311,7 +311,7 @@
def InvalidNoreturn : DiagGroup<"invalid-noreturn">;
def InvalidSourceEncoding : DiagGroup<"invalid-source-encoding">;
def KNRPromotedParameter : DiagGroup<"knr-promoted-parameter">;
-def : DiagGroup<"init-self">;
+def InitSelf : DiagGroup<"init-self">;
def : DiagGroup<"inline">;
def : DiagGroup<"invalid-pch">;
def GNULabelsAsValue : DiagGroup<"gnu-label-as-value">;
@@ -775,6 +775,7 @@
Format,
Implicit,
InfiniteRecursion,
+ InitSelf,
MismatchedTags,
MissingBraces,
Move,
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
