[clang] 6f7d824 - [Clang][Sema]: Diagnose lambda to bool implicit casts (#83152)
via cfe-commits
cfe-commits at lists.llvm.org
Thu Feb 29 06:09:51 PST 2024
Author: Vinayak Dev
Date: 2024-02-29T09:09:39-05:00
New Revision: 6f7d824b804b272335d55f5b899295db833f3829
URL: https://github.com/llvm/llvm-project/commit/6f7d824b804b272335d55f5b899295db833f3829
DIFF: https://github.com/llvm/llvm-project/commit/6f7d824b804b272335d55f5b899295db833f3829.diff
LOG: [Clang][Sema]: Diagnose lambda to bool implicit casts (#83152)
Adds diagnostics for lambda expressions being cast to boolean values,
which results in the expression always evaluating to true.
Earlier, Clang allowed compilation of such erroneous programs, but now
emits a warning through `-Wpointer-bool-conversion`.
Fixes #82512
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaChecking.cpp
clang/test/CXX/drs/dr18xx.cpp
clang/test/CXX/expr/expr.prim/expr.prim.lambda/blocks.mm
clang/test/SemaCXX/warn-bool-conversion.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 7e16b9f0c67dbd..a5c6b80c4e99e1 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -192,6 +192,9 @@ Improvements to Clang's diagnostics
- Clang now diagnoses declarative nested name specifiers that name alias templates.
+- Clang now diagnoses lambda function expressions being implicitly cast to boolean values, under ``-Wpointer-bool-conversion``.
+ Fixes `#82512 <https://github.com/llvm/llvm-project/issues/82512>`_.
+
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 378b537e029710..ff88c4f293abfd 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -4127,8 +4127,8 @@ def ext_ms_impcast_fn_obj : ExtWarn<
"Microsoft extension">, InGroup<MicrosoftCast>;
def warn_impcast_pointer_to_bool : Warning<
- "address of%select{| function| array}0 '%1' will always evaluate to "
- "'true'">,
+ "address of %select{'%1'|function '%1'|array '%1'|lambda function pointer "
+ "conversion operator}0 will always evaluate to 'true'">,
InGroup<PointerBoolConversion>;
def warn_cast_nonnull_to_bool : Warning<
"nonnull %select{function call|parameter}0 '%1' will evaluate to "
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 979b63884359fc..35d453e013e84b 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -16544,6 +16544,17 @@ void Sema::DiagnoseAlwaysNonNullPointer(Expr *E,
}
}
+ // Complain if we are converting a lambda expression to a boolean value
+ if (const auto *MCallExpr = dyn_cast<CXXMemberCallExpr>(E)) {
+ if (const auto *MRecordDecl = MCallExpr->getRecordDecl();
+ MRecordDecl && MRecordDecl->isLambda()) {
+ Diag(E->getExprLoc(), diag::warn_impcast_pointer_to_bool)
+ << /*LambdaPointerConversionOperatorType=*/3
+ << MRecordDecl->getSourceRange() << Range << IsEqual;
+ return;
+ }
+ }
+
// Expect to find a single Decl. Skip anything more complicated.
ValueDecl *D = nullptr;
if (DeclRefExpr *R = dyn_cast<DeclRefExpr>(E)) {
diff --git a/clang/test/CXX/drs/dr18xx.cpp b/clang/test/CXX/drs/dr18xx.cpp
index a7cee4ef8902f9..e78730e8992cf8 100644
--- a/clang/test/CXX/drs/dr18xx.cpp
+++ b/clang/test/CXX/drs/dr18xx.cpp
@@ -282,6 +282,7 @@ namespace dr1837 { // dr1837: 3.3
struct A {
int f();
bool b = [] {
+ // since-cxx11-warning at -1 {{address of lambda function pointer conversion operator will always evaluate to 'true'}}
struct Local {
static_assert(sizeof(this->f()) == sizeof(int), "");
};
diff --git a/clang/test/CXX/expr/expr.prim/expr.prim.lambda/blocks.mm b/clang/test/CXX/expr/expr.prim/expr.prim.lambda/blocks.mm
index cb56f6816ad036..e93c37f3b9ae12 100644
--- a/clang/test/CXX/expr/expr.prim/expr.prim.lambda/blocks.mm
+++ b/clang/test/CXX/expr/expr.prim/expr.prim.lambda/blocks.mm
@@ -65,10 +65,10 @@ void nesting() {
namespace overloading {
void bool_conversion() {
- if ([](){}) {
+ if ([](){}) { // expected-warning{{address of lambda function pointer conversion operator will always evaluate to 'true'}}
}
- bool b = []{};
+ bool b = []{}; // expected-warning{{address of lambda function pointer conversion operator will always evaluate to 'true'}}
b = (bool)[]{};
}
@@ -108,8 +108,9 @@ void call_with_lambda() {
using decltype(a)::operator id<void(*)()>; // expected-note {{here}}
} extern d;
- bool r1 = c;
- bool r2 = d; // expected-error {{private}}
+ bool r1 = c; // expected-warning{{address of lambda function pointer conversion operator will always evaluate to 'true'}}
+ bool r2 = d; // expected-error {{private}} \
+ expected-warning{{address of lambda function pointer conversion operator will always evaluate to 'true'}}
}
namespace PR13117 {
diff --git a/clang/test/SemaCXX/warn-bool-conversion.cpp b/clang/test/SemaCXX/warn-bool-conversion.cpp
index c81d52d864f2d2..9e8cf0e4f8944a 100644
--- a/clang/test/SemaCXX/warn-bool-conversion.cpp
+++ b/clang/test/SemaCXX/warn-bool-conversion.cpp
@@ -81,6 +81,18 @@ struct S2 {
bool f5();
bool f6(int);
+#if __cplusplus >= 201103L
+auto f7 = []{};
+auto f8 = [](){};
+
+void foo() {
+ bool b;
+ b = f7; // expected-warning {{address of lambda function pointer conversion operator will always evaluate to 'true'}}
+ b = f8; // expected-warning {{address of lambda function pointer conversion operator will always evaluate to 'true'}}
+ bool is_true = [](){ return true; };
+ // expected-warning at -1{{address of lambda function pointer conversion operator will always evaluate to 'true'}}
+}
+#endif
void bar() {
bool b;
More information about the cfe-commits
mailing list