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Remove the fixit for the diagnostics regarding capturing autoreleasing variables in a block

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The fixit is actively harmful, as it encourages developers to ignore the
warning and to write unsafe code.
It is almost impossible to write safe code while capturing autoreleasing
variables in the block, as in order to check that the block is never
called in the autoreleasing pool the developer has to check the
transitive closure of all potential callers of the block.

Differential Revision: https://reviews.llvm.org/D46778

llvm-svn: 332288
This commit is contained in:
George Karpenkov 2018-05-14 20:29:16 +00:00
parent 7129e63bcc
commit 098f0080da
3 changed files with 7 additions and 39 deletions
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2
clang/include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -5435,8 +5435,6 @@ def warn_block_capture_autoreleasing : Warning<
"block captures an autoreleasing out-parameter, which may result in "
"use-after-free bugs">,
InGroup<BlockCaptureAutoReleasing>;
def note_declare_parameter_autoreleasing : Note<
"declare the parameter __autoreleasing explicitly to suppress this warning">;
def note_declare_parameter_strong : Note<
"declare the parameter __strong or capture a __block __strong variable to "
"keep values alive across autorelease pools">;

24
clang/lib/Sema/SemaExpr.cpp
View File

@ -14579,30 +14579,6 @@ static bool captureInBlock(BlockScopeInfo *BSI, VarDecl *Var,
if (BuildAndDiagnose) {
SourceLocation VarLoc = Var->getLocation();
S.Diag(Loc, diag::warn_block_capture_autoreleasing);
{
auto AddAutoreleaseNote =
S.Diag(VarLoc, diag::note_declare_parameter_autoreleasing);
// Provide a fix-it for the '__autoreleasing' keyword at the
// appropriate location in the variable's type.
if (const auto *TSI = Var->getTypeSourceInfo()) {
PointerTypeLoc PTL =
TSI->getTypeLoc().getAsAdjusted<PointerTypeLoc>();
if (PTL) {
SourceLocation Loc = PTL.getPointeeLoc().getEndLoc();
Loc = Lexer::getLocForEndOfToken(Loc, 0, S.getSourceManager(),
S.getLangOpts());
if (Loc.isValid()) {
StringRef CharAtLoc = Lexer::getSourceText(
CharSourceRange::getCharRange(Loc, Loc.getLocWithOffset(1)),
S.getSourceManager(), S.getLangOpts());
AddAutoreleaseNote << FixItHint::CreateInsertion(
Loc, CharAtLoc.empty() || !isWhitespace(CharAtLoc[0])
? " __autoreleasing "
: " __autoreleasing");
}
}
}
}
S.Diag(VarLoc, diag::note_declare_parameter_strong);
}
}

20
clang/test/SemaObjC/arc.m
View File

@ -1,5 +1,5 @@
// RUN: %clang_cc1 -triple x86_64-apple-darwin11 -fobjc-runtime-has-weak -fsyntax-only -fobjc-arc -fblocks -verify -Wno-objc-root-class %s
// RUN: not %clang_cc1 -triple x86_64-apple-darwin11 -fobjc-runtime-has-weak -fsyntax-only -fobjc-arc -fblocks -Wno-objc-root-class -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
// RUN: not %clang_cc1 -triple x86_64-apple-darwin11 -fobjc-runtime-has-weak -fsyntax-only -fobjc-arc -fblocks -Wno-objc-root-class -fdiagnostics-parseable-fixits %s 2>&1
typedef unsigned long NSUInteger;
typedef const void * CFTypeRef;
@ -811,23 +811,17 @@ int garf() {
}
void block_capture_autoreleasing(A * __autoreleasing *a,
A **b, // expected-note {{declare the parameter __autoreleasing explicitly to suppress this warning}} expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
A * _Nullable *c, // expected-note {{declare the parameter __autoreleasing explicitly to suppress this warning}} expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
A **b, // expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
A * _Nullable *c, // expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
A * _Nullable __autoreleasing *d,
A ** _Nullable e, // expected-note {{declare the parameter __autoreleasing explicitly to suppress this warning}} expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
A ** _Nullable e, // expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
A * __autoreleasing * _Nullable f,
id __autoreleasing *g,
id *h, // expected-note {{declare the parameter __autoreleasing explicitly to suppress this warning}} expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
id _Nullable *i, // expected-note {{declare the parameter __autoreleasing explicitly to suppress this warning}} expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
id *h, // expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
id _Nullable *i, // expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
id _Nullable __autoreleasing *j,
id * _Nullable k, // expected-note {{declare the parameter __autoreleasing explicitly to suppress this warning}} expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
id * _Nullable k, // expected-note {{declare the parameter __strong or capture a __block __strong variable to keep values alive across autorelease pools}}
id __autoreleasing * _Nullable l) {
// CHECK: fix-it:"{{.*}}":{[[@LINE-11]]:37-[[@LINE-11]]:37}:" __autoreleasing "
// CHECK: fix-it:"{{.*}}":{[[@LINE-11]]:47-[[@LINE-11]]:47}:" __autoreleasing"
// CHECK: fix-it:"{{.*}}":{[[@LINE-10]]:37-[[@LINE-10]]:37}:" __autoreleasing "
// CHECK: fix-it:"{{.*}}":{[[@LINE-8]]:36-[[@LINE-8]]:36}:" __autoreleasing"
// CHECK: fix-it:"{{.*}}":{[[@LINE-8]]:46-[[@LINE-8]]:46}:" __autoreleasing"
// CHECK: fix-it:"{{.*}}":{[[@LINE-7]]:36-[[@LINE-7]]:36}:" __autoreleasing"
^{
(void)*a;
(void)*b; // expected-warning {{block captures an autoreleasing out-parameter, which may result in use-after-free bugs}}