[clang] [clang] Add -Wmissing-designated-field-initializers (PR #81364)
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Sat Feb 10 08:35:03 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Vadim D. (vvd170501)
<details>
<summary>Changes</summary>
Fixes #<!-- -->68933.
#<!-- -->56628 changed the behavior of `-Wmissing-field-initializers`, which introduces many new warnings in C++ code that uses partial designated initializers. If such code is being built with `-Wextra -Werror`, this change will break the build.
This PR adds a new flag that allows to disable these new warnings, as was suggested by @<!-- -->AaronBallman in the original issue: https://github.com/llvm/llvm-project/issues/56628#issuecomment-1761510850
---
Full diff: https://github.com/llvm/llvm-project/pull/81364.diff
4 Files Affected:
- (modified) clang/include/clang/Basic/DiagnosticGroups.td (+9-1)
- (modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (+4)
- (modified) clang/lib/Sema/SemaInit.cpp (+26-24)
- (modified) clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp (+6-5)
``````````diff
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 975eca0ad9b642..bda533f77cc56a 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -516,7 +516,15 @@ def MethodSignatures : DiagGroup<"method-signatures">;
def MismatchedParameterTypes : DiagGroup<"mismatched-parameter-types">;
def MismatchedReturnTypes : DiagGroup<"mismatched-return-types">;
def MismatchedTags : DiagGroup<"mismatched-tags">;
-def MissingFieldInitializers : DiagGroup<"missing-field-initializers">;
+def MissingDesignatedFieldInitializers : DiagGroup<"missing-designated-field-initializers">{
+ code Documentation = [{
+Warn about designated initializers with some fields missing (only in C++).
+ }];
+}
+// Default -Wmissing-field-initializers matches gcc behavior,
+// but missing-designated-field-initializers can be turned off to match old clang behavior.
+def MissingFieldInitializers : DiagGroup<"missing-field-initializers",
+ [MissingDesignatedFieldInitializers]>;
def ModuleLock : DiagGroup<"module-lock">;
def ModuleBuild : DiagGroup<"module-build">;
def ModuleImport : DiagGroup<"module-import">;
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index b4dc4feee8e63a..69e197e26b9b45 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -6165,6 +6165,10 @@ def ext_initializer_string_for_char_array_too_long : ExtWarn<
def warn_missing_field_initializers : Warning<
"missing field %0 initializer">,
InGroup<MissingFieldInitializers>, DefaultIgnore;
+// The same warning, but another group is needed to disable it separately.
+def warn_missing_designated_field_initializers : Warning<
+ "missing field %0 initializer">,
+ InGroup<MissingDesignatedFieldInitializers>, DefaultIgnore;
def warn_braces_around_init : Warning<
"braces around %select{scalar |}0initializer">,
InGroup<DiagGroup<"braced-scalar-init">>;
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index b6de06464cd6f3..08aa50ebad331f 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -2227,8 +2227,6 @@ 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;
@@ -2269,11 +2267,6 @@ void InitListChecker::CheckStructUnionTypes(
}
InitializedSomething = true;
-
- // Disable check for missing fields when designators are used.
- // This matches gcc behaviour.
- if (!SemaRef.getLangOpts().CPlusPlus)
- CheckForMissingFields = false;
continue;
}
@@ -2285,7 +2278,7 @@ void InitListChecker::CheckStructUnionTypes(
// These are okay for randomized structures. [C99 6.7.8p19]
//
// Also, if there is only one element in the structure, we allow something
- // like this, because it's really not randomized in the tranditional sense.
+ // like this, because it's really not randomized in the traditional sense.
//
// struct foo h = {bar};
auto IsZeroInitializer = [&](const Expr *I) {
@@ -2363,23 +2356,32 @@ void InitListChecker::CheckStructUnionTypes(
}
// 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 (!VerifyOnly && InitializedSomething && !RD->isUnion()) {
+ // Disable missing fields check for:
+ // - Zero initializers
+ // - Designated initializers (only in C). This matches gcc behaviour.
+ bool DisableCheck =
+ IList->isIdiomaticZeroInitializer(SemaRef.getLangOpts()) ||
+ (HasDesignatedInit && !SemaRef.getLangOpts().CPlusPlus);
+
+ if (!DisableCheck) {
+ // 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;
+ if (!it->isUnnamedBitfield() && !it->hasInClassInitializer() &&
+ !it->getType()->isIncompleteArrayType()) {
+ auto Diag = HasDesignatedInit
+ ? diag::warn_missing_designated_field_initializers
+ : diag::warn_missing_field_initializers;
+ SemaRef.Diag(IList->getSourceRange().getEnd(), Diag) << *it;
+ break;
+ }
}
}
}
diff --git a/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp b/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
index 510ace58c35a6a..1e9c5fa082d077 100644
--- a/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
+++ b/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
@@ -4,7 +4,8 @@
// 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
-// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,wmissing -Wmissing-field-initializers -Wno-c99-designator -Wno-reorder-init-list -Wno-initializer-overrides
+// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,wmissing,wmissing-designated -Wmissing-field-initializers -Wno-c99-designator -Wno-reorder-init-list -Wno-initializer-overrides
+// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,wmissing -Wmissing-field-initializers -Wno-missing-designated-field-initializers -Wno-c99-designator -Wno-reorder-init-list -Wno-initializer-overrides
namespace class_with_ctor {
@@ -50,11 +51,11 @@ A a3 = {
A a4 = {
.x = 1, // override-note {{previous}}
.x = 1 // override-error {{overrides prior initialization}}
-}; // wmissing-warning {{missing field 'y' initializer}}
+}; // wmissing-designated-warning {{missing field 'y' initializer}}
A a5 = {
.y = 1, // override-note {{previous}}
.y = 1 // override-error {{overrides prior initialization}}
-}; // wmissing-warning {{missing field 'x' initializer}}
+}; // wmissing-designated-warning {{missing field 'x' initializer}}
B b2 = {.a = 1}; // pedantic-error {{brace elision for designated initializer is a C99 extension}}
// wmissing-warning at -1 {{missing field 'y' initializer}}
B b3 = {.a = 1, 2}; // pedantic-error {{mixture of designated and non-designated}} pedantic-note {{first non-designated}} pedantic-error {{brace elision}}
@@ -74,8 +75,8 @@ C c = {
struct Foo { int a, b; };
struct Foo foo0 = { 1 }; // wmissing-warning {{missing field 'b' initializer}}
-struct Foo foo1 = { .a = 1 }; // wmissing-warning {{missing field 'b' initializer}}
-struct Foo foo2 = { .b = 1 }; // wmissing-warning {{missing field 'a' initializer}}
+struct Foo foo1 = { .a = 1 }; // wmissing-designated-warning {{missing field 'b' initializer}}
+struct Foo foo2 = { .b = 1 }; // wmissing-designated-warning {{missing field 'a' initializer}}
}
``````````
</details>
https://github.com/llvm/llvm-project/pull/81364
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