efriedma created this revision.
efriedma added reviewers: rsmith, erik.pilkington, aaron.ballman.
efriedma requested review of this revision.
Herald added a project: clang.
Similar to variables with an initializer, this is never valid in standard C, so
we can safely constant-fold as an extension. I ran into this construct in a
couple proprietary codebases.
While I'm here, drive-by fix for 090dd647
<https://reviews.llvm.org/rG090dd647d98dc50a56a42fbba0f3f11b10a3a187>: we
should only fold variables with VLA types, not arbitrary variably modified
types.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D98363
Files:
clang/include/clang/Sema/Sema.h
clang/lib/Sema/SemaDecl.cpp
clang/lib/Sema/SemaExpr.cpp
clang/test/Sema/vla.c
Index: clang/test/Sema/vla.c
===================================================================
--- clang/test/Sema/vla.c
+++ clang/test/Sema/vla.c
@@ -129,4 +129,9 @@
// 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}};
+
+ // expected-warning@+1{{variable length array folded to constant array as an extension}}
+ char (*a9)[] = (char[2][ksize]) {{1,2,3,4},{4,3,2,1}};
+
+ char (*a10)[ksize] = 0;
}
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -6833,9 +6833,12 @@
diag::err_array_incomplete_or_sizeless_type,
SourceRange(LParenLoc, LiteralExpr->getSourceRange().getEnd())))
return ExprError();
- if (literalType->isVariableArrayType())
- return ExprError(Diag(LParenLoc, diag::err_variable_object_no_init)
- << SourceRange(LParenLoc, LiteralExpr->getSourceRange().getEnd()));
+ if (literalType->isVariableArrayType()) {
+ if (!tryToFixVariablyModifiedVarType(TInfo, literalType, LParenLoc,
+ diag::err_variable_object_no_init)) {
+ return ExprError();
+ }
+ }
} else if (!literalType->isDependentType() &&
RequireCompleteType(LParenLoc, literalType,
diag::err_typecheck_decl_incomplete_type,
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -6038,26 +6038,26 @@
/// Attempt to fold a variable-sized type to a constant-sized type, returning
/// true if we were successful.
-static bool tryToFixVariablyModifiedVarType(Sema &S, TypeSourceInfo *&TInfo,
- QualType &T, SourceLocation Loc,
- unsigned FailedFoldDiagID) {
+bool Sema::tryToFixVariablyModifiedVarType(TypeSourceInfo *&TInfo,
+ QualType &T, SourceLocation Loc,
+ unsigned FailedFoldDiagID) {
bool SizeIsNegative;
llvm::APSInt Oversized;
TypeSourceInfo *FixedTInfo = TryToFixInvalidVariablyModifiedTypeSourceInfo(
- TInfo, S.Context, SizeIsNegative, Oversized);
+ TInfo, Context, SizeIsNegative, Oversized);
if (FixedTInfo) {
- S.Diag(Loc, diag::ext_vla_folded_to_constant);
+ 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);
+ Diag(Loc, diag::err_typecheck_negative_array_size);
else if (Oversized.getBoolValue())
- S.Diag(Loc, diag::err_array_too_large) << Oversized.toString(10);
+ Diag(Loc, diag::err_array_too_large) << Oversized.toString(10);
else if (FailedFoldDiagID)
- S.Diag(Loc, FailedFoldDiagID);
+ Diag(Loc, FailedFoldDiagID);
return false;
}
@@ -6894,10 +6894,10 @@
}
}
- // If this variable has a variable-modified type and an initializer, try to
+ // If this variable has a VLA type and an initializer, try to
// fold to a constant-sized type. This is otherwise invalid.
- if (D.hasInitializer() && R->isVariablyModifiedType())
- tryToFixVariablyModifiedVarType(*this, TInfo, R, D.getIdentifierLoc(),
+ if (D.hasInitializer() && R->isVariableArrayType())
+ tryToFixVariablyModifiedVarType(TInfo, R, D.getIdentifierLoc(),
/*DiagID=*/0);
bool IsMemberSpecialization = false;
@@ -16734,7 +16734,7 @@
// than a variably modified type.
if (!InvalidDecl && T->isVariablyModifiedType()) {
if (!tryToFixVariablyModifiedVarType(
- *this, TInfo, T, Loc, diag::err_typecheck_field_variable_size))
+ TInfo, T, Loc, diag::err_typecheck_field_variable_size))
InvalidDecl = true;
}
@@ -16962,7 +16962,7 @@
// than a variably modified type.
else if (T->isVariablyModifiedType()) {
if (!tryToFixVariablyModifiedVarType(
- *this, TInfo, T, Loc, diag::err_typecheck_ivar_variable_size))
+ TInfo, T, Loc, diag::err_typecheck_ivar_variable_size))
D.setInvalidType();
}
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -2579,6 +2579,9 @@
NamedDecl *HandleDeclarator(Scope *S, Declarator &D,
MultiTemplateParamsArg TemplateParameterLists);
+ bool tryToFixVariablyModifiedVarType(TypeSourceInfo *&TInfo,
+ QualType &T, SourceLocation Loc,
+ unsigned FailedFoldDiagID);
void RegisterLocallyScopedExternCDecl(NamedDecl *ND, Scope *S);
bool DiagnoseClassNameShadow(DeclContext *DC, DeclarationNameInfo Info);
bool diagnoseQualifiedDeclaration(CXXScopeSpec &SS, DeclContext *DC,
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