sgilles created this revision.
sgilles added reviewers: cfe-commits, rsmith, zaks.anna.
Add ZeroInitializer as a language option, attached to all standards of
C. Relax checks for -Wmissing-field-initializers and -Wmissing-braces so
that, for such languages, assigning to a structure with { 0 } produces
no warnings. Add tests.
This fixes PR21689, which is mentioned by the Austin Group at
http://austingroupbugs.net/view.php?id=918 . It does not extend this
treatment of { 0 } to C++.
Patch by S. Gilles
https://reviews.llvm.org/D28148
Files:
include/clang/Basic/LangOptions.def
include/clang/Frontend/LangStandard.h
include/clang/Frontend/LangStandards.def
lib/Frontend/CompilerInvocation.cpp
lib/Sema/SemaInit.cpp
test/Sema/zero-initializer.c
Index: test/Sema/zero-initializer.c
===================================================================
--- /dev/null
+++ test/Sema/zero-initializer.c
@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -std=c99 -Wmissing-field-initializers -Wmissing-braces
+
+struct foo {
+ /* */
+ int x;
+ int y;
+};
+
+struct bar {
+ /* */
+ struct foo a;
+ struct foo b;
+};
+
+int main(void)
+{
+ struct foo f = { 0 }; // expected-no-diagnostics
+ struct foo g = { 9 }; // expected-warning {{missing field 'y' initializer}}
+ struct foo h = { 9, 9 }; // expected-no-diagnostics
+ struct bar i = { 0 }; // expected-no-diagnostics
+ struct bar j = { 0, 0 }; // expected-warning {{suggest braces around initialization of suboject}} expected-warning {{missing field 'b' initializer}}
+ struct bar k = { { 9, 9 }, { 9, 9 } }; // expected-no-diagnostics
+ struct bar l = { { 9, 9 }, { 0 } }; // expected-no-diagnostics
+ struct bar m = { { 0 }, { 0 } }; // expected-no-diagnostics
+ struct bar n = { { 0 }, { 9, 9 } }; // expected-no-diagnostics
+ struct bar o = { { 9, 9 }, { 0 } }; // expected-no-diagnostics
+ struct bar p = { { 9 }, { 9, 9 } }; // expected-warning {{missing field 'y' initializer}}
+
+ return f.x + g.x + h.x + i.a.x + j.a.x + k.a.x + l.a.x + m.a.x + n.a.x +
+ o.a.x + p.a.x;
+}
Index: lib/Sema/SemaInit.cpp
===================================================================
--- lib/Sema/SemaInit.cpp
+++ lib/Sema/SemaInit.cpp
@@ -880,8 +880,19 @@
StructuredSubobjectInitList->setRBraceLoc(EndLoc);
}
+ bool MissingBracesOkay = false;
+
+ if (SemaRef.getLangOpts().ZeroInitializer &&
+ StructuredSubobjectInitList->getNumInits() == 1) {
+ if (const IntegerLiteral *lit = dyn_cast<IntegerLiteral>(StructuredSubobjectInitList->getInit(0))) {
+ if (lit->getValue() == 0) {
+ MissingBracesOkay = true;
+ }
+ }
+ }
+
// Complain about missing braces.
- if (T->isArrayType() || T->isRecordType()) {
+ if (!MissingBracesOkay && (T->isArrayType() || T->isRecordType())) {
SemaRef.Diag(StructuredSubobjectInitList->getLocStart(),
diag::warn_missing_braces)
<< StructuredSubobjectInitList->getSourceRange()
@@ -1828,6 +1839,17 @@
RecordDecl *RD = DeclType->getAs<RecordType>()->getDecl();
RecordDecl::field_iterator FieldEnd = RD->field_end();
bool CheckForMissingFields = true;
+
+ // Check if this is C's zero initializer { 0 }
+ if (SemaRef.getLangOpts().ZeroInitializer &&
+ IList->getNumInits() == 1) {
+ if (const IntegerLiteral *lit = dyn_cast<IntegerLiteral>(IList->getInit(0))) {
+ if (lit->getValue() == 0) {
+ CheckForMissingFields = false;
+ }
+ }
+ }
+
while (Index < IList->getNumInits()) {
Expr *Init = IList->getInit(Index);
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -1599,6 +1599,7 @@
Opts.GNUInline = Std.isC89();
Opts.HexFloats = Std.hasHexFloats();
Opts.ImplicitInt = Std.hasImplicitInt();
+ Opts.ZeroInitializer = Std.hasZeroInitializer();
// Set OpenCL Version.
Opts.OpenCL = isOpenCL(LangStd) || IK == IK_OpenCL;
Index: include/clang/Frontend/LangStandards.def
===================================================================
--- include/clang/Frontend/LangStandards.def
+++ include/clang/Frontend/LangStandards.def
@@ -30,66 +30,66 @@
// C89-ish modes.
LANGSTANDARD(c89, "c89",
"ISO C 1990",
- C89 | ImplicitInt)
+ C89 | ImplicitInt | ZeroInitializer)
LANGSTANDARD(c90, "c90",
"ISO C 1990",
- C89 | ImplicitInt)
+ C89 | ImplicitInt | ZeroInitializer)
LANGSTANDARD(iso9899_1990, "iso9899:1990",
"ISO C 1990",
- C89 | ImplicitInt)
+ C89 | ImplicitInt | ZeroInitializer)
LANGSTANDARD(c94, "iso9899:199409",
"ISO C 1990 with amendment 1",
- C89 | Digraphs | ImplicitInt)
+ C89 | Digraphs | ImplicitInt | ZeroInitializer)
LANGSTANDARD(gnu89, "gnu89",
"ISO C 1990 with GNU extensions",
- LineComment | C89 | Digraphs | GNUMode | ImplicitInt)
+ LineComment | C89 | Digraphs | GNUMode | ImplicitInt | ZeroInitializer)
LANGSTANDARD(gnu90, "gnu90",
"ISO C 1990 with GNU extensions",
- LineComment | C89 | Digraphs | GNUMode | ImplicitInt)
+ LineComment | C89 | Digraphs | GNUMode | ImplicitInt | ZeroInitializer)
// C99-ish modes
LANGSTANDARD(c99, "c99",
"ISO C 1999",
- LineComment | C99 | Digraphs | HexFloat)
+ LineComment | C99 | Digraphs | HexFloat | ZeroInitializer)
LANGSTANDARD(c9x, "c9x",
"ISO C 1999",
- LineComment | C99 | Digraphs | HexFloat)
+ LineComment | C99 | Digraphs | HexFloat | ZeroInitializer)
LANGSTANDARD(iso9899_1999,
"iso9899:1999", "ISO C 1999",
- LineComment | C99 | Digraphs | HexFloat)
+ LineComment | C99 | Digraphs | HexFloat | ZeroInitializer)
LANGSTANDARD(iso9899_199x,
"iso9899:199x", "ISO C 1999",
- LineComment | C99 | Digraphs | HexFloat)
+ LineComment | C99 | Digraphs | HexFloat | ZeroInitializer)
LANGSTANDARD(gnu99, "gnu99",
"ISO C 1999 with GNU extensions",
- LineComment | C99 | Digraphs | GNUMode | HexFloat)
+ LineComment | C99 | Digraphs | GNUMode | HexFloat | ZeroInitializer)
LANGSTANDARD(gnu9x, "gnu9x",
"ISO C 1999 with GNU extensions",
- LineComment | C99 | Digraphs | GNUMode | HexFloat)
+ LineComment | C99 | Digraphs | GNUMode | HexFloat | ZeroInitializer)
// C11 modes
LANGSTANDARD(c11, "c11",
"ISO C 2011",
- LineComment | C99 | C11 | Digraphs | HexFloat)
+ LineComment | C99 | C11 | Digraphs | HexFloat | ZeroInitializer)
LANGSTANDARD(c1x, "c1x",
"ISO C 2011",
- LineComment | C99 | C11 | Digraphs | HexFloat)
+ LineComment | C99 | C11 | Digraphs | HexFloat | ZeroInitializer)
LANGSTANDARD(iso9899_2011,
"iso9899:2011", "ISO C 2011",
- LineComment | C99 | C11 | Digraphs | HexFloat)
+ LineComment | C99 | C11 | Digraphs | HexFloat | ZeroInitializer)
LANGSTANDARD(iso9899_201x,
"iso9899:201x", "ISO C 2011",
- LineComment | C99 | C11 | Digraphs | HexFloat)
+ LineComment | C99 | C11 | Digraphs | HexFloat | ZeroInitializer)
LANGSTANDARD(gnu11, "gnu11",
"ISO C 2011 with GNU extensions",
- LineComment | C99 | C11 | Digraphs | GNUMode | HexFloat)
+ LineComment | C99 | C11 | Digraphs | GNUMode | HexFloat | ZeroInitializer)
LANGSTANDARD(gnu1x, "gnu1x",
"ISO C 2011 with GNU extensions",
- LineComment | C99 | C11 | Digraphs | GNUMode | HexFloat)
+ LineComment | C99 | C11 | Digraphs | GNUMode | HexFloat | ZeroInitializer)
// C++ modes
LANGSTANDARD(cxx98, "c++98",
Index: include/clang/Frontend/LangStandard.h
===================================================================
--- include/clang/Frontend/LangStandard.h
+++ include/clang/Frontend/LangStandard.h
@@ -29,7 +29,8 @@
Digraphs = (1 << 8),
GNUMode = (1 << 9),
HexFloat = (1 << 10),
- ImplicitInt = (1 << 11)
+ ImplicitInt = (1 << 11),
+ ZeroInitializer = (1 << 12)
};
}
@@ -91,6 +92,9 @@
/// hasImplicitInt - Language allows variables to be typed as int implicitly.
bool hasImplicitInt() const { return Flags & frontend::ImplicitInt; }
+ /// hasZeroInitializer - Language considers { 0 } idiomatic.
+ bool hasZeroInitializer() const { return Flags & frontend::ZeroInitializer; }
+
static const LangStandard &getLangStandardForKind(Kind K);
static const LangStandard *getLangStandardForName(StringRef Name);
};
Index: include/clang/Basic/LangOptions.def
===================================================================
--- include/clang/Basic/LangOptions.def
+++ include/clang/Basic/LangOptions.def
@@ -111,6 +111,7 @@
LANGOPT(GNUKeywords , 1, 1, "GNU keywords")
BENIGN_LANGOPT(ImplicitInt, 1, !C99 && !CPlusPlus, "C89 implicit 'int'")
LANGOPT(Digraphs , 1, 0, "digraphs")
+LANGOPT(ZeroInitializer , 1, C99, "C's treatment of {0}")
BENIGN_LANGOPT(HexFloats , 1, C99, "C99 hexadecimal float constants")
LANGOPT(CXXOperatorNames , 1, 0, "C++ operator name keywords")
LANGOPT(AppleKext , 1, 0, "Apple kext support")
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