erik.pilkington created this revision.
erik.pilkington added reviewers: rsmith, rjmccall, arphaman.
Herald added subscribers: ributzka, jkorous.
erik.pilkington requested review of this revision.
D89523 <https://reviews.llvm.org/D89523> removed support for promoting VLAs to
constant arrays when the bounds isn't an ICE, since this can result in
miscompiling a conforming program that assumes that the array is a VLA.
Promoting VLAs for fields is still supported, since clang doesn't support VLAs
in fields, so no conforming program could have a field VLA.
This change is really disruptive for us (hundreds of projects are failing to
compile with this change), so I think we should carve out two more cases where
we promote VLAs which can't miscompile a conforming program:
1. When the VLA appears in an ivar -- this seems like a corollary to the field
thing
2. When the VLA has an initializer -- VLAs can't have an initializer
Thanks for taking a look!
https://reviews.llvm.org/D90871
Files:
clang/include/clang/Sema/Sema.h
clang/lib/Parse/ParseDecl.cpp
clang/lib/Sema/SemaDecl.cpp
clang/test/Sema/decl-in-prototype.c
clang/test/Sema/vla.c
clang/test/SemaObjC/variable-size-ivar.m
Index: clang/test/SemaObjC/variable-size-ivar.m
===================================================================
--- /dev/null
+++ clang/test/SemaObjC/variable-size-ivar.m
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -fsyntax-only %s -verify
+
+const int ksize = 42;
+int size = 42;
+
+@interface X
+{
+ int arr1[ksize]; // expected-warning{{variable length array folded to constant array}}
+ int arr2[size]; // expected-error{{instance variables must have a constant size}}
+ int arr3[ksize-43]; // expected-error{{array size is negative}}
+}
+@end
Index: clang/test/Sema/vla.c
===================================================================
--- clang/test/Sema/vla.c
+++ clang/test/Sema/vla.c
@@ -100,3 +100,29 @@
typedef struct {
char c[pr44406_a]; // expected-warning {{folded to constant array as an extension}}
} pr44406_s;
+
+void test_fold_to_constant_array() {
+ const int ksize = 4;
+
+ goto jump_over_a1; // expected-error{{cannot jump from this goto statement to its label}}
+ char a1[ksize]; // expected-note{{variable length array}}
+ jump_over_a1:;
+
+ char a2[ksize] = "foo"; // expected-warning{{variable length array folded to constant array as an extension}}
+
+ char a3[ksize] = {}; // expected-warning {{variable length array folded to constant array as an extension}} expected-warning{{use of GNU empty initializer}}
+
+ goto jump_over_a4; // expected-error{{cannot jump from this goto statement to its label}}
+ char a4[ksize][2]; // expected-note{{variable length array}}
+ jump_over_a4:;
+
+ char a5[ksize][2] = {}; // expected-warning {{variable length array folded to constant array as an extension}} expected-warning{{use of GNU empty initializer}}
+
+ int a6[ksize] = {1,2,3,4}; // expected-warning{{variable length array folded to constant array as an extension}}
+
+ // expected-warning@+1{{variable length array folded to constant array as an extension}}
+ int a7[ksize] __attribute__((annotate("foo"))) = {1,2,3,4};
+
+ // expected-warning@+1{{variable length array folded to constant array as an extension}}
+ char a8[2][ksize] = {{1,2,3,4},{4,3,2,1}};
+}
Index: clang/test/Sema/decl-in-prototype.c
===================================================================
--- clang/test/Sema/decl-in-prototype.c
+++ clang/test/Sema/decl-in-prototype.c
@@ -49,7 +49,7 @@
// function.
enum { BB = 0 };
void enum_in_fun_in_fun(void (*fp)(enum { AA, BB } e)) { // expected-warning {{will not be visible}}
- SA(1, AA == 5); // expected-error {{variable-sized object may not be initialized}}
+ SA(1, AA == 5); // expected-warning{{variable length array folded to constant array as an extension}}
SA(2, BB == 0);
}
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -5542,9 +5542,9 @@
return false;
}
-Decl *Sema::ActOnDeclarator(Scope *S, Declarator &D) {
+Decl *Sema::ActOnDeclarator(Scope *S, Declarator &D, bool NextTokIsEqual) {
D.setFunctionDefinitionKind(FDK_Declaration);
- Decl *Dcl = HandleDeclarator(S, D, MultiTemplateParamsArg());
+ Decl *Dcl = HandleDeclarator(S, D, MultiTemplateParamsArg(), NextTokIsEqual);
if (OriginalLexicalContext && OriginalLexicalContext->isObjCContainer() &&
Dcl && Dcl->getDeclContext()->isFileContext())
@@ -5678,7 +5678,8 @@
}
NamedDecl *Sema::HandleDeclarator(Scope *S, Declarator &D,
- MultiTemplateParamsArg TemplateParamLists) {
+ MultiTemplateParamsArg TemplateParamLists,
+ bool NextTokIsEqual) {
// TODO: consider using NameInfo for diagnostic.
DeclarationNameInfo NameInfo = GetNameForDeclarator(D);
DeclarationName Name = NameInfo.getName();
@@ -5873,7 +5874,7 @@
AddToScope);
} else {
New = ActOnVariableDeclarator(S, D, DC, TInfo, Previous, TemplateParamLists,
- AddToScope);
+ AddToScope, /*Bindings=*/None, NextTokIsEqual);
}
if (!New)
@@ -6023,6 +6024,31 @@
return FixedTInfo;
}
+/// Attempt to fold a variable-sized type to a constant-sized type, returning
+/// true if it we were successful.
+static bool tryToFixVariablyModifiedVarType(Sema &S, TypeSourceInfo *&TInfo,
+ QualType &T, SourceLocation Loc,
+ unsigned FailedFoldDiagID) {
+ bool SizeIsNegative;
+ llvm::APSInt Oversized;
+ TypeSourceInfo *FixedTInfo = TryToFixInvalidVariablyModifiedTypeSourceInfo(
+ TInfo, S.Context, SizeIsNegative, Oversized);
+ if (FixedTInfo) {
+ S.Diag(Loc, diag::ext_vla_folded_to_constant);
+ TInfo = FixedTInfo;
+ T = FixedTInfo->getType();
+ return true;
+ }
+
+ if (SizeIsNegative)
+ S.Diag(Loc, diag::err_typecheck_negative_array_size);
+ else if (Oversized.getBoolValue())
+ S.Diag(Loc, diag::err_array_too_large) << Oversized.toString(10);
+ else if (FailedFoldDiagID)
+ S.Diag(Loc, FailedFoldDiagID);
+ return false;
+}
+
/// Register the given locally-scoped extern "C" declaration so
/// that it can be found later for redeclarations. We include any extern "C"
/// declaration that is not visible in the translation unit here, not just
@@ -6797,7 +6823,8 @@
NamedDecl *Sema::ActOnVariableDeclarator(
Scope *S, Declarator &D, DeclContext *DC, TypeSourceInfo *TInfo,
LookupResult &Previous, MultiTemplateParamsArg TemplateParamLists,
- bool &AddToScope, ArrayRef<BindingDecl *> Bindings) {
+ bool &AddToScope, ArrayRef<BindingDecl *> Bindings,
+ bool NextTokIsEqual) {
QualType R = TInfo->getType();
DeclarationName Name = GetNameForDeclarator(D).getName();
@@ -6871,6 +6898,10 @@
VarTemplateDecl *NewTemplate = nullptr;
TemplateParameterList *TemplateParams = nullptr;
if (!getLangOpts().CPlusPlus) {
+ if (NextTokIsEqual && R->isVariablyModifiedType())
+ tryToFixVariablyModifiedVarType(*this, TInfo, R, D.getIdentifierLoc(),
+ /*DiagID=*/0);
+
NewVD = VarDecl::Create(Context, DC, D.getBeginLoc(), D.getIdentifierLoc(),
II, R, TInfo, SC);
@@ -16628,27 +16659,9 @@
// C99 6.7.2.1p8: A member of a structure or union may have any type other
// than a variably modified type.
if (!InvalidDecl && T->isVariablyModifiedType()) {
- bool SizeIsNegative;
- llvm::APSInt Oversized;
-
- TypeSourceInfo *FixedTInfo =
- TryToFixInvalidVariablyModifiedTypeSourceInfo(TInfo, Context,
- SizeIsNegative,
- Oversized);
- if (FixedTInfo) {
- Diag(Loc, diag::ext_vla_folded_to_constant);
- TInfo = FixedTInfo;
- T = FixedTInfo->getType();
- } else {
- if (SizeIsNegative)
- Diag(Loc, diag::err_typecheck_negative_array_size);
- else if (Oversized.getBoolValue())
- Diag(Loc, diag::err_array_too_large)
- << Oversized.toString(10);
- else
- Diag(Loc, diag::err_typecheck_field_variable_size);
+ if (!tryToFixVariablyModifiedVarType(
+ *this, TInfo, T, Loc, diag::err_typecheck_field_variable_size))
InvalidDecl = true;
- }
}
// Fields can not have abstract class types
@@ -16869,8 +16882,9 @@
// C99 6.7.2.1p8: A member of a structure or union may have any type other
// than a variably modified type.
else if (T->isVariablyModifiedType()) {
- Diag(Loc, diag::err_typecheck_ivar_variable_size);
- D.setInvalidType();
+ if (!tryToFixVariablyModifiedVarType(
+ *this, TInfo, T, Loc, diag::err_typecheck_ivar_variable_size))
+ D.setInvalidType();
}
// Get the visibility (access control) for this ivar.
Index: clang/lib/Parse/ParseDecl.cpp
===================================================================
--- clang/lib/Parse/ParseDecl.cpp
+++ clang/lib/Parse/ParseDecl.cpp
@@ -2193,12 +2193,13 @@
}
};
- // Inform the current actions module that we just parsed this declarator.
+ // Inform Sema that we just parsed this declarator.
Decl *ThisDecl = nullptr;
Decl *OuterDecl = nullptr;
switch (TemplateInfo.Kind) {
case ParsedTemplateInfo::NonTemplate:
- ThisDecl = Actions.ActOnDeclarator(getCurScope(), D);
+ ThisDecl = Actions.ActOnDeclarator(getCurScope(), D,
+ /*HasInit=*/Tok.is(tok::equal));
break;
case ParsedTemplateInfo::Template:
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -2475,10 +2475,11 @@
SourceLocation Less,
SourceLocation Greater);
- Decl *ActOnDeclarator(Scope *S, Declarator &D);
+ Decl *ActOnDeclarator(Scope *S, Declarator &D, bool NextTokIsEqual = false);
NamedDecl *HandleDeclarator(Scope *S, Declarator &D,
- MultiTemplateParamsArg TemplateParameterLists);
+ MultiTemplateParamsArg TemplateParameterLists,
+ bool NextTokIsEqual = false);
void RegisterLocallyScopedExternCDecl(NamedDecl *ND, Scope *S);
bool DiagnoseClassNameShadow(DeclContext *DC, DeclarationNameInfo Info);
bool diagnoseQualifiedDeclaration(CXXScopeSpec &SS, DeclContext *DC,
@@ -2529,7 +2530,8 @@
LookupResult &Previous,
MultiTemplateParamsArg TemplateParamLists,
bool &AddToScope,
- ArrayRef<BindingDecl *> Bindings = None);
+ ArrayRef<BindingDecl *> Bindings = None,
+ bool NextTokIsEqual = false);
NamedDecl *
ActOnDecompositionDeclarator(Scope *S, Declarator &D,
MultiTemplateParamsArg TemplateParamLists);
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