mbenfield updated this revision to Diff 337877.
mbenfield added a comment.
Updates in response to comments.
- Parameters.empty() and early exit.
- comments in VisitDeclRefExpr.
- clearer description of the warnings.
Also, changed the name of DiagnoseUnusedDecls to DiagnoseUnusedButSetDecls for
clarity and to avoid confusion with Sema::DiagnoseUnusedDecl.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D100581/new/
https://reviews.llvm.org/D100581
Files:
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/include/clang/Sema/Sema.h
clang/lib/Sema/SemaDecl.cpp
clang/lib/Sema/SemaExpr.cpp
clang/lib/Sema/SemaStmt.cpp
clang/test/Sema/vector-gcc-compat.c
clang/test/Sema/warn-unused-but-set-parameters-cpp.cpp
clang/test/Sema/warn-unused-but-set-parameters.c
clang/test/Sema/warn-unused-but-set-variables-cpp.cpp
clang/test/Sema/warn-unused-but-set-variables.c
Index: clang/test/Sema/warn-unused-but-set-variables.c
===================================================================
--- /dev/null
+++ clang/test/Sema/warn-unused-but-set-variables.c
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -fblocks -fsyntax-only -Wunused-but-set-variable -verify %s
+
+struct S {
+ int i;
+};
+
+int f0() {
+ int y; // expected-warning{{variable 'y' set but not used}}
+ y = 0;
+
+ int z __attribute__((unused));
+ z = 0;
+
+ struct S s; // expected-warning{{variable 's' set but not used}}
+ struct S t;
+ s = t;
+
+ int x;
+ x = 0;
+ return x;
+}
+
+void f1(void) {
+ (void)^() {
+ int y; // expected-warning{{variable 'y' set but not used}}
+ y = 0;
+
+ int x;
+ x = 0;
+ return x;
+ };
+}
Index: clang/test/Sema/warn-unused-but-set-variables-cpp.cpp
===================================================================
--- /dev/null
+++ clang/test/Sema/warn-unused-but-set-variables-cpp.cpp
@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 -fblocks -fsyntax-only -Wunused-but-set-variable -verify %s
+
+struct S {
+ int i;
+};
+
+int f0() {
+ int y; // expected-warning{{variable 'y' set but not used}}
+ y = 0;
+
+ int z __attribute__((unused));
+ z = 0;
+
+ // no warning for structs in C++
+ struct S s;
+ struct S t;
+ s = t;
+
+ int x;
+ x = 0;
+ return x;
+}
+
+void f1(void) {
+ (void)^() {
+ int y; // expected-warning{{variable 'y' set but not used}}
+ y = 0;
+
+ int x;
+ x = 0;
+ return x;
+ };
+}
Index: clang/test/Sema/warn-unused-but-set-parameters.c
===================================================================
--- /dev/null
+++ clang/test/Sema/warn-unused-but-set-parameters.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -fblocks -fsyntax-only -Wunused-but-set-parameter -verify %s
+
+int f0(int x,
+ int y, // expected-warning{{parameter 'y' set but not used}}
+ int z __attribute__((unused))) {
+ y = 0;
+ return x;
+}
+
+void f1(void) {
+ (void)^(int x,
+ int y, // expected-warning{{parameter 'y' set but not used}}
+ int z __attribute__((unused))) {
+ y = 0;
+ return x;
+ };
+}
+
+struct S {
+ int i;
+};
+
+void f3(struct S s) { // expected-warning{{parameter 's' set but not used}}
+ struct S t;
+ s = t;
+}
Index: clang/test/Sema/warn-unused-but-set-parameters-cpp.cpp
===================================================================
--- /dev/null
+++ clang/test/Sema/warn-unused-but-set-parameters-cpp.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -fblocks -fsyntax-only -Wunused-but-set-parameter -verify %s
+
+int f0(int x,
+ int y, // expected-warning{{parameter 'y' set but not used}}
+ int z __attribute__((unused))) {
+ y = 0;
+ return x;
+}
+
+void f1(void) {
+ (void)^(int x,
+ int y, // expected-warning{{parameter 'y' set but not used}}
+ int z __attribute__((unused))) {
+ y = 0;
+ return x;
+ };
+}
+
+struct S {
+ int i;
+};
+
+// in C++, don't warn for a struct
+void f3(struct S s) {
+ struct S t;
+ s = t;
+}
Index: clang/test/Sema/vector-gcc-compat.c
===================================================================
--- clang/test/Sema/vector-gcc-compat.c
+++ clang/test/Sema/vector-gcc-compat.c
@@ -35,7 +35,7 @@
void arithmeticTest(void) {
v2i64 v2i64_a = (v2i64){0, 1};
- v2i64 v2i64_r;
+ v2i64 v2i64_r; // expected-warning{{variable 'v2i64_r' set but not used}}
v2i64_r = v2i64_a + 1;
v2i64_r = v2i64_a - 1;
@@ -58,7 +58,7 @@
void comparisonTest(void) {
v2i64 v2i64_a = (v2i64){0, 1};
- v2i64 v2i64_r;
+ v2i64 v2i64_r; // expected-warning{{variable 'v2i64_r' set but not used}}
v2i64_r = v2i64_a == 1;
v2i64_r = v2i64_a != 1;
@@ -78,8 +78,8 @@
void logicTest(void) {
v2i64 v2i64_a = (v2i64){0, 1};
v2i64 v2i64_b = (v2i64){2, 1};
- v2i64 v2i64_c = (v2i64){3, 1};
- v2i64 v2i64_r;
+ v2i64 v2i64_c = (v2i64){3, 1}; // expected-warning{{variable 'v2i64_c' set but not used}}
+ v2i64 v2i64_r; // expected-warning{{variable 'v2i64_r' set but not used}}
v2i64_r = !v2i64_a; // expected-error {{invalid argument type 'v2i64' (vector of 2 'long long' values) to unary expression}}
v2i64_r = ~v2i64_a;
@@ -132,7 +132,7 @@
void floatTestConstantComparison(void) {
v4f32 v4f32_a = {0.4f, 0.4f, 0.4f, 0.4f};
- v4i32 v4i32_r;
+ v4i32 v4i32_r; // expected-warning{{variable 'v4i32_r' set but not used}}
v4i32_r = v4f32_a > 0.4f;
v4i32_r = v4f32_a >= 0.4f;
v4i32_r = v4f32_a < 0.4f;
@@ -143,7 +143,7 @@
void doubleTestConstantComparison(void) {
v2f64 v2f64_a = {0.4, 0.4};
- v2i64 v2i64_r;
+ v2i64 v2i64_r; // expected-warning{{variable 'v2i64_r' set but not used}}
v2i64_r = v2f64_a > 0.4;
v2i64_r = v2f64_a >= 0.4;
v2i64_r = v2f64_a < 0.4;
Index: clang/lib/Sema/SemaStmt.cpp
===================================================================
--- clang/lib/Sema/SemaStmt.cpp
+++ clang/lib/Sema/SemaStmt.cpp
@@ -433,7 +433,9 @@
DiagnoseEmptyLoopBody(Elts[i], Elts[i + 1]);
}
- return CompoundStmt::Create(Context, Elts, L, R);
+ CompoundStmt *CS = CompoundStmt::Create(Context, Elts, L, R);
+ DiagnoseUnusedButSetVariables(CS);
+ return CS;
}
ExprResult
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -15498,6 +15498,9 @@
BD->setBody(cast<CompoundStmt>(Body));
+ // wait to diagnose unused but set parameters until after setBody
+ DiagnoseUnusedButSetParameters(BD->parameters());
+
if (Body && getCurFunction()->HasPotentialAvailabilityViolations)
DiagnoseUnguardedAvailabilityViolations(BD);
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -24,6 +24,7 @@
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/NonTrivialTypeVisitor.h"
+#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/StmtCXX.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/PartialDiagnostic.h"
@@ -43,6 +44,7 @@
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/Template.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Triple.h"
#include <algorithm>
@@ -13733,6 +13735,143 @@
}
}
+// values in Map should be true. traverses Body; if any key is used in any way
+// other than assigning to it, sets the corresponding value to false.
+static void AreAllUsesSets(Stmt *Body,
+ llvm::SmallDenseMap<NamedDecl *, bool> *Map) {
+
+ struct AllUsesAreSetsVisitor : RecursiveASTVisitor<AllUsesAreSetsVisitor> {
+ llvm::SmallDenseMap<NamedDecl *, bool> *M;
+ unsigned FalseCount = 0;
+
+ AllUsesAreSetsVisitor(llvm::SmallDenseMap<NamedDecl *, bool> *Map)
+ : M(Map) {}
+
+ bool TraverseBinaryOperator(BinaryOperator *BO) {
+ auto *LHS = BO->getLHS();
+ auto *DRE = dyn_cast<DeclRefExpr>(LHS);
+ if (!DRE || M->find(DRE->getFoundDecl()) == M->end()) {
+ // the LHS is not a reference to one of our NamedDecls
+ TraverseStmt(LHS);
+ }
+ TraverseStmt(BO->getRHS());
+ return true;
+ }
+
+ bool VisitDeclRefExpr(const DeclRefExpr *DRE) {
+ auto iter = M->find(DRE->getFoundDecl());
+ if (iter != M->end() && iter->second) {
+ // we've found a use of this Decl that's not the LHS of an assignment
+ iter->second = false;
+ ++FalseCount;
+ if (FalseCount == M->size()) {
+ // we've found uses for every Decl in Map; no need to continue walking
+ // the AST
+ return false;
+ }
+ }
+ return true;
+ }
+ };
+
+ if (!Map->size())
+ return;
+
+ AllUsesAreSetsVisitor Visitor(Map);
+ Visitor.TraverseStmt(Body);
+}
+
+template <typename R>
+static void DiagnoseUnusedButSetDecls(Sema *Se, Stmt *Body, R Decls,
+ unsigned DiagID) {
+ // put the Decls in a map so we only have to traverse the body once for all of
+ // them
+ llvm::SmallDenseMap<NamedDecl *, bool> AllUsesAreSets;
+
+ for (NamedDecl *ND : Decls) {
+ AllUsesAreSets.insert(std::make_pair(ND, true));
+ }
+
+ AreAllUsesSets(Body, &AllUsesAreSets);
+
+ for (const auto Pair : AllUsesAreSets) {
+ if (Pair.second) {
+ Se->Diag(Pair.first->getLocation(), DiagID) << Pair.first->getDeclName();
+ }
+ }
+}
+
+void Sema::DiagnoseUnusedButSetParameters(ArrayRef<ParmVarDecl *> Parameters) {
+ // Don't diagnose unused-but-set-parameter errors in template instantiations;
+ // we will already have done so in the template itself.
+ if (inTemplateInstantiation())
+ return;
+
+ bool CPlusPlus = getLangOpts().CPlusPlus;
+
+ auto IsCandidate = [CPlusPlus, &Diags = Diags](ParmVarDecl *P) {
+ // check for Ignored here, because if we have no candidates we can avoid
+ // walking the AST
+ if (Diags.getDiagnosticLevel(diag::warn_unused_but_set_parameter,
+ P->getLocation()) ==
+ DiagnosticsEngine::Ignored)
+ return false;
+ if (!P->isReferenced() || !P->getDeclName() || P->hasAttr<UnusedAttr>())
+ return false;
+ // mimic gcc's behavior regarding nonscalar types
+ if (CPlusPlus && !P->getType()->isScalarType())
+ return false;
+ return true;
+ };
+
+ auto Candidates = llvm::make_filter_range(Parameters, IsCandidate);
+
+ if (Parameters.empty())
+ return;
+
+ Decl *D = Decl::castFromDeclContext((*Parameters.begin())->getDeclContext());
+ Stmt *Body = D->getBody();
+ if (Body)
+ DiagnoseUnusedDecls(this, Body, Candidates,
+ diag::warn_unused_but_set_parameter);
+}
+
+void Sema::DiagnoseUnusedButSetVariables(CompoundStmt *CS) {
+ bool CPlusPlus = getLangOpts().CPlusPlus;
+
+ auto IsCandidate = [CPlusPlus, &Diags = Diags](Stmt *S) {
+ DeclStmt *SD = dyn_cast<DeclStmt>(S);
+ if (!SD || !SD->isSingleDecl())
+ return false;
+ VarDecl *VD = dyn_cast<VarDecl>(SD->getSingleDecl());
+ if (!VD || !VD->isReferenced() || !VD->getDeclName() ||
+ VD->hasAttr<UnusedAttr>())
+ return false;
+ // check for Ignored here, because if we have no candidates we can avoid
+ // walking the AST
+ if (Diags.getDiagnosticLevel(diag::warn_unused_but_set_variable,
+ VD->getLocation()) ==
+ DiagnosticsEngine::Ignored)
+ return false;
+ // mimic gcc's behavior regarding nonscalar types
+ if (CPlusPlus && !VD->getType()->isScalarType())
+ return false;
+ return true;
+ };
+
+ auto Candidates = llvm::make_filter_range(CS->body(), IsCandidate);
+
+ auto ToNamedDecl = [](Stmt *S) {
+ DeclStmt *SD = dyn_cast<DeclStmt>(S);
+ return dyn_cast<NamedDecl>(SD->getSingleDecl());
+ };
+
+ auto CandidateDecls = llvm::map_range(Candidates, ToNamedDecl);
+
+ DiagnoseUnusedDecls(this, CS, CandidateDecls,
+ diag::warn_unused_but_set_variable);
+}
+
void Sema::DiagnoseSizeOfParametersAndReturnValue(
ArrayRef<ParmVarDecl *> Parameters, QualType ReturnTy, NamedDecl *D) {
if (LangOpts.NumLargeByValueCopy == 0) // No check.
@@ -14435,8 +14574,10 @@
if (!FD->isInvalidDecl()) {
// Don't diagnose unused parameters of defaulted or deleted functions.
- if (!FD->isDeleted() && !FD->isDefaulted() && !FD->hasSkippedBody())
+ if (!FD->isDeleted() && !FD->isDefaulted() && !FD->hasSkippedBody()) {
DiagnoseUnusedParameters(FD->parameters());
+ DiagnoseUnusedButSetParameters(FD->parameters());
+ }
DiagnoseSizeOfParametersAndReturnValue(FD->parameters(),
FD->getReturnType(), FD);
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -2827,6 +2827,13 @@
/// ParmVarDecl pointers.
void DiagnoseUnusedParameters(ArrayRef<ParmVarDecl *> Parameters);
+ /// Diagnose any unused but set parameters in the given sequence of
+ /// ParmVarDecl pointers.
+ void DiagnoseUnusedButSetParameters(ArrayRef<ParmVarDecl *> Parameters);
+
+ /// Diagnose any unused but set variables declared in this CompoundStmt
+ void DiagnoseUnusedButSetVariables(CompoundStmt *CS);
+
/// Diagnose whether the size of parameters or return value of a
/// function or obj-c method definition is pass-by-value and larger than a
/// specified threshold.
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -310,8 +310,12 @@
"repeated RISC-V 'interrupt' attribute is here">;
def warn_unused_parameter : Warning<"unused parameter %0">,
InGroup<UnusedParameter>, DefaultIgnore;
+def warn_unused_but_set_parameter : Warning<"parameter %0 set but not used">,
+ InGroup<UnusedButSetParameter>, DefaultIgnore;
def warn_unused_variable : Warning<"unused variable %0">,
InGroup<UnusedVariable>, DefaultIgnore;
+def warn_unused_but_set_variable : Warning<"variable %0 set but not used">,
+ InGroup<UnusedButSetVariable>, DefaultIgnore;
def warn_unused_local_typedef : Warning<
"unused %select{typedef|type alias}0 %1">,
InGroup<UnusedLocalTypedef>, DefaultIgnore;
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -720,6 +720,8 @@
def UnusedLabel : DiagGroup<"unused-label">;
def UnusedLambdaCapture : DiagGroup<"unused-lambda-capture">;
def UnusedParameter : DiagGroup<"unused-parameter">;
+def UnusedButSetParameter : DiagGroup<"unused-but-set-parameter">;
+def UnusedButSetVariable : DiagGroup<"unused-but-set-variable">;
def UnusedResult : DiagGroup<"unused-result">;
def PotentiallyEvaluatedExpression : DiagGroup<"potentially-evaluated-expression">;
def UnevaluatedExpression : DiagGroup<"unevaluated-expression",
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