[clang] a01307a - [clang] Fix false positive -Wmissing-field-initializer for anonymous unions (#70829)
via cfe-commits
cfe-commits at lists.llvm.org
Tue Dec 12 23:48:35 PST 2023
Author: Mariya Podchishchaeva
Date: 2023-12-13T08:48:32+01:00
New Revision: a01307a6ee788fc6ac2e09e58f0f52e5666def86
URL: https://github.com/llvm/llvm-project/commit/a01307a6ee788fc6ac2e09e58f0f52e5666def86
DIFF: https://github.com/llvm/llvm-project/commit/a01307a6ee788fc6ac2e09e58f0f52e5666def86.diff
LOG: [clang] Fix false positive -Wmissing-field-initializer for anonymous unions (#70829)
Normally warning is not reported when a field has default initializer.
Do so for anonymous unions with default initializers as well. No release
note since it is a regression in clang 18.
Fixes https://github.com/llvm/llvm-project/issues/70384
Added:
Modified:
clang/lib/Sema/SemaInit.cpp
clang/test/Sema/missing-field-initializers.c
clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
Removed:
################################################################################
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 5ca6b232df66a5..4028b2d642b212 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -465,7 +465,8 @@ class InitListChecker {
void FillInEmptyInitForField(unsigned Init, FieldDecl *Field,
const InitializedEntity &ParentEntity,
InitListExpr *ILE, bool &RequiresSecondPass,
- bool FillWithNoInit = false);
+ bool FillWithNoInit = false,
+ bool WarnIfMissing = false);
void FillInEmptyInitializations(const InitializedEntity &Entity,
InitListExpr *ILE, bool &RequiresSecondPass,
InitListExpr *OuterILE, unsigned OuterIndex,
@@ -654,11 +655,16 @@ void InitListChecker::FillInEmptyInitForBase(
}
}
-void InitListChecker::FillInEmptyInitForField(unsigned Init, FieldDecl *Field,
- const InitializedEntity &ParentEntity,
- InitListExpr *ILE,
- bool &RequiresSecondPass,
- bool FillWithNoInit) {
+static bool hasAnyDesignatedInits(const InitListExpr *IL) {
+ return llvm::any_of(*IL, [=](const Stmt *Init) {
+ return isa_and_nonnull<DesignatedInitExpr>(Init);
+ });
+}
+
+void InitListChecker::FillInEmptyInitForField(
+ unsigned Init, FieldDecl *Field, const InitializedEntity &ParentEntity,
+ InitListExpr *ILE, bool &RequiresSecondPass, bool FillWithNoInit,
+ bool WarnIfMissing) {
SourceLocation Loc = ILE->getEndLoc();
unsigned NumInits = ILE->getNumInits();
InitializedEntity MemberEntity
@@ -726,15 +732,52 @@ void InitListChecker::FillInEmptyInitForField(unsigned Init, FieldDecl *Field,
if (hadError || VerifyOnly) {
// Do nothing
- } else if (Init < NumInits) {
- ILE->setInit(Init, MemberInit.getAs<Expr>());
- } else if (!isa<ImplicitValueInitExpr>(MemberInit.get())) {
- // Empty initialization requires a constructor call, so
- // extend the initializer list to include the constructor
- // call and make a note that we'll need to take another pass
- // through the initializer list.
- ILE->updateInit(SemaRef.Context, Init, MemberInit.getAs<Expr>());
- RequiresSecondPass = true;
+ } else {
+ if (WarnIfMissing) {
+ auto CheckAnonMember = [&](const FieldDecl *FD,
+ auto &&CheckAnonMember) -> FieldDecl * {
+ FieldDecl *Uninitialized = nullptr;
+ RecordDecl *RD = FD->getType()->getAsRecordDecl();
+ assert(RD && "Not anonymous member checked?");
+ for (auto *F : RD->fields()) {
+ FieldDecl *UninitializedFieldInF = nullptr;
+ if (F->isAnonymousStructOrUnion())
+ UninitializedFieldInF = CheckAnonMember(F, CheckAnonMember);
+ else if (!F->isUnnamedBitfield() &&
+ !F->getType()->isIncompleteArrayType() &&
+ !F->hasInClassInitializer())
+ UninitializedFieldInF = F;
+
+ if (RD->isUnion() && !UninitializedFieldInF)
+ return nullptr;
+ if (!Uninitialized)
+ Uninitialized = UninitializedFieldInF;
+ }
+ return Uninitialized;
+ };
+
+ FieldDecl *FieldToDiagnose = nullptr;
+ if (Field->isAnonymousStructOrUnion())
+ FieldToDiagnose = CheckAnonMember(Field, CheckAnonMember);
+ else if (!Field->isUnnamedBitfield() &&
+ !Field->getType()->isIncompleteArrayType())
+ FieldToDiagnose = Field;
+
+ if (FieldToDiagnose)
+ SemaRef.Diag(Loc, diag::warn_missing_field_initializers)
+ << FieldToDiagnose;
+ }
+
+ if (Init < NumInits) {
+ ILE->setInit(Init, MemberInit.getAs<Expr>());
+ } else if (!isa<ImplicitValueInitExpr>(MemberInit.get())) {
+ // Empty initialization requires a constructor call, so
+ // extend the initializer list to include the constructor
+ // call and make a note that we'll need to take another pass
+ // through the initializer list.
+ ILE->updateInit(SemaRef.Context, Init, MemberInit.getAs<Expr>());
+ RequiresSecondPass = true;
+ }
}
} else if (InitListExpr *InnerILE
= dyn_cast<InitListExpr>(ILE->getInit(Init))) {
@@ -802,9 +845,25 @@ InitListChecker::FillInEmptyInitializations(const InitializedEntity &Entity,
}
}
} else {
+ InitListExpr *SForm =
+ ILE->isSyntacticForm() ? ILE : ILE->getSyntacticForm();
// The fields beyond ILE->getNumInits() are default initialized, so in
// order to leave them uninitialized, the ILE is expanded and the extra
// fields are then filled with NoInitExpr.
+
+ // Some checks that are required for missing fields warning are bound to
+ // how many elements the initializer list originally was provided; perform
+ // them before the list is expanded.
+ bool WarnIfMissingField =
+ !SForm->isIdiomaticZeroInitializer(SemaRef.getLangOpts()) &&
+ ILE->getNumInits();
+
+ // Disable check for missing fields when designators are used in C to
+ // match gcc behaviour.
+ // FIXME: Should we emulate possible gcc warning bug?
+ WarnIfMissingField &=
+ SemaRef.getLangOpts().CPlusPlus || !hasAnyDesignatedInits(SForm);
+
unsigned NumElems = numStructUnionElements(ILE->getType());
if (!RDecl->isUnion() && RDecl->hasFlexibleArrayMember())
++NumElems;
@@ -832,7 +891,7 @@ InitListChecker::FillInEmptyInitializations(const InitializedEntity &Entity,
return;
FillInEmptyInitForField(Init, Field, Entity, ILE, RequiresSecondPass,
- FillWithNoInit);
+ FillWithNoInit, WarnIfMissingField);
if (hadError)
return;
@@ -947,13 +1006,6 @@ InitListChecker::FillInEmptyInitializations(const InitializedEntity &Entity,
}
}
-static bool hasAnyDesignatedInits(const InitListExpr *IL) {
- for (const Stmt *Init : *IL)
- if (isa_and_nonnull<DesignatedInitExpr>(Init))
- return true;
- return false;
-}
-
InitListChecker::InitListChecker(
Sema &S, const InitializedEntity &Entity, InitListExpr *IL, QualType &T,
bool VerifyOnly, bool TreatUnavailableAsInvalid, bool InOverloadResolution,
@@ -2225,12 +2277,8 @@ void InitListChecker::CheckStructUnionTypes(
size_t NumRecordDecls = llvm::count_if(RD->decls(), [&](const Decl *D) {
return isa<FieldDecl>(D) || isa<RecordDecl>(D);
});
- bool CheckForMissingFields =
- !IList->isIdiomaticZeroInitializer(SemaRef.getLangOpts());
bool HasDesignatedInit = false;
- llvm::SmallPtrSet<FieldDecl *, 4> InitializedFields;
-
while (Index < IList->getNumInits()) {
Expr *Init = IList->getInit(Index);
SourceLocation InitLoc = Init->getBeginLoc();
@@ -2254,24 +2302,17 @@ void InitListChecker::CheckStructUnionTypes(
// Find the field named by the designated initializer.
DesignatedInitExpr::Designator *D = DIE->getDesignator(0);
- if (!VerifyOnly && D->isFieldDesignator()) {
+ if (!VerifyOnly && D->isFieldDesignator() && !DesignatedInitFailed) {
FieldDecl *F = D->getFieldDecl();
- InitializedFields.insert(F);
- if (!DesignatedInitFailed) {
- QualType ET = SemaRef.Context.getBaseElementType(F->getType());
- if (checkDestructorReference(ET, InitLoc, SemaRef)) {
- hadError = true;
- return;
- }
+ QualType ET = SemaRef.Context.getBaseElementType(F->getType());
+ if (checkDestructorReference(ET, InitLoc, SemaRef)) {
+ hadError = true;
+ return;
}
}
InitializedSomething = true;
- // Disable check for missing fields when designators are used.
- // This matches gcc behaviour.
- if (!SemaRef.getLangOpts().CPlusPlus)
- CheckForMissingFields = false;
continue;
}
@@ -2350,7 +2391,6 @@ void InitListChecker::CheckStructUnionTypes(
CheckSubElementType(MemberEntity, IList, Field->getType(), Index,
StructuredList, StructuredIndex);
InitializedSomething = true;
- InitializedFields.insert(*Field);
if (RD->isUnion() && StructuredList) {
// Initialize the first field within the union.
@@ -2360,28 +2400,6 @@ void InitListChecker::CheckStructUnionTypes(
++Field;
}
- // Emit warnings for missing struct field initializers.
- if (!VerifyOnly && InitializedSomething && CheckForMissingFields &&
- !RD->isUnion()) {
- // It is possible we have one or more unnamed bitfields remaining.
- // Find first (if any) named field and emit warning.
- for (RecordDecl::field_iterator it = HasDesignatedInit ? RD->field_begin()
- : Field,
- end = RD->field_end();
- it != end; ++it) {
- if (HasDesignatedInit && InitializedFields.count(*it))
- continue;
-
- if (!it->isUnnamedBitfield() && !it->hasInClassInitializer() &&
- !it->getType()->isIncompleteArrayType()) {
- SemaRef.Diag(IList->getSourceRange().getEnd(),
- diag::warn_missing_field_initializers)
- << *it;
- break;
- }
- }
- }
-
// Check that any remaining fields can be value-initialized if we're not
// building a structured list. (If we are, we'll check this later.)
if (!StructuredList && Field != FieldEnd && !RD->isUnion() &&
diff --git a/clang/test/Sema/missing-field-initializers.c b/clang/test/Sema/missing-field-initializers.c
index 1e65b2d62e1ab8..8653591ff1187a 100644
--- a/clang/test/Sema/missing-field-initializers.c
+++ b/clang/test/Sema/missing-field-initializers.c
@@ -18,7 +18,7 @@ struct Foo bar1[] = {
1, 2,
1, 2,
1
-}; // expected-warning {{missing field 'b' initializer}}
+}; // expected-warning at -1 {{missing field 'b' initializer}}
struct Foo bar2[] = { {}, {}, {} };
diff --git a/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp b/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
index 510ace58c35a6a..0d977e07ed034e 100644
--- a/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
+++ b/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
@@ -1,6 +1,6 @@
// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,pedantic,override,reorder -pedantic-errors
// RUN: %clang_cc1 -std=c++17 %s -verify=expected,pedantic,override,reorder -Wno-c++20-designator -pedantic-errors
-// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,pedantic -Werror=c99-designator -Wno-reorder-init-list -Wno-initializer-overrides
+// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,pedantic -Werror=c99-designator -Wno-reorder-init-list -Wno-initializer-overrides -Werror=nested-anon-types -Werror=gnu-anonymous-struct
// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,reorder -Wno-c99-designator -Werror=reorder-init-list -Wno-initializer-overrides
// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,override -Wno-c99-designator -Wno-reorder-init-list -Werror=initializer-overrides
// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected -Wno-c99-designator -Wno-reorder-init-list -Wno-initializer-overrides
@@ -39,6 +39,7 @@ A a1 = {
};
int arr[3] = {[1] = 5}; // pedantic-error {{array designators are a C99 extension}}
B b = {.a.x = 0}; // pedantic-error {{nested designators are a C99 extension}}
+ // wmissing-warning at -1 {{missing field 'y' initializer}}
A a2 = {
.x = 1, // pedantic-error {{mixture of designated and non-designated initializers in the same initializer list is a C99 extension}}
2 // pedantic-note {{first non-designated initializer is here}}
@@ -60,7 +61,6 @@ B b2 = {.a = 1}; // pedantic-error {{brace elision for designated initializer is
B b3 = {.a = 1, 2}; // pedantic-error {{mixture of designated and non-designated}} pedantic-note {{first non-designated}} pedantic-error {{brace elision}}
B b4 = {.a = 1, 2, 3}; // pedantic-error {{mixture of designated and non-designated}} pedantic-note {{first non-designated}} pedantic-error {{brace elision}} expected-error {{excess elements}}
B b5 = {.a = nullptr}; // expected-error {{cannot initialize}}
- // wmissing-warning at -1 {{missing field 'y' initializer}}
struct C { int :0, x, :0, y, :0; };
C c = {
.x = 1, // override-note {{previous}}
@@ -247,3 +247,87 @@ void foo() {
//
}
}
+
+namespace GH70384 {
+
+struct A {
+ int m;
+ union { int a; float n = 0; };
+};
+
+struct B {
+ int m;
+ int b;
+ union { int a ; };
+};
+
+union CU {
+ int a = 1;
+ double b;
+};
+
+struct C {
+ int a;
+ union { int b; CU c;};
+};
+
+struct CC {
+ int a;
+ CU c;
+};
+
+void foo() {
+ A a = A{.m = 0};
+ A aa = {0};
+ A aaa = {.a = 7}; // wmissing-warning {{missing field 'm' initializer}}
+ B b = {.m = 1, .b = 3 }; //wmissing-warning {{missing field 'a' initializer}}
+ B bb = {1}; // wmissing-warning {{missing field 'b' initializer}}
+ // wmissing-warning at -1 {{missing field 'a' initializer}}
+ C c = {.a = 1}; // wmissing-warning {{missing field 'b' initializer}}
+ CC cc = {.a = 1}; // wmissing-warning {{missing field 'c' initializer}}
+}
+
+struct C1 {
+ int m;
+ union { float b; union {int n = 1; }; };
+ // pedantic-error at -1 {{anonymous types declared in an anonymous union are an extension}}
+};
+
+struct C2 {
+ int m;
+ struct { float b; int n = 1; }; // pedantic-error {{anonymous structs are a GNU extension}}
+};
+
+struct C3 {
+ int m;
+ struct { float b = 1; union {int a;}; int n = 1; };
+ // pedantic-error at -1 {{anonymous structs are a GNU extension}}
+ // pedantic-error at -2 {{anonymous types declared in an anonymous struct are an extension}}
+};
+
+C1 c = C1{.m = 1};
+C1 cc = C1{.b = 1}; // wmissing-warning {{missing field 'm' initializer}}
+C2 c1 = C2{.m = 1}; // wmissing-warning {{missing field 'b' initializer}}
+C2 c22 = C2{.m = 1, .b = 1};
+C3 c2 = C3{.b = 1}; // wmissing-warning {{missing field 'a' initializer}}
+ // wmissing-warning at -1 {{missing field 'm' initializer}}
+
+struct C4 {
+ union {
+ struct { int n; }; // pedantic-error {{anonymous structs are a GNU extension}}
+ // pedantic-error at -1 {{anonymous types declared in an anonymous union are an extension}}
+ int m = 0; };
+ int z;
+};
+C4 a = {.z = 1};
+
+struct C5 {
+ int a;
+ struct { // pedantic-error {{anonymous structs are a GNU extension}}
+ int x;
+ struct { int y = 0; }; // pedantic-error {{anonymous types declared in an anonymous struct are an extension}}
+ // pedantic-error at -1 {{anonymous structs are a GNU extension}}
+ };
+};
+C5 c5 = C5{.a = 0}; //wmissing-warning {{missing field 'x' initializer}}
+}
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