From: Matthew Curtis Date: Thu, 3 Oct 2013 12:14:24 +0000 (+0000) Subject: Gracefully (and correctly) handle init of multiple union members X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4e49952712ff9b1b1696cb07580b2b24a3ca99e1;p=clang Gracefully (and correctly) handle init of multiple union members We now emit warnings when doing so and code generation is consistent with GCC. Note that the C99 spec is unclear as to the precise behavior. See also ... Bug: http://llvm.org/bugs/show_bug.cgi?id=16644 and cfe-dev discussion: http://lists.cs.uiuc.edu/pipermail/cfe-dev/2013-September/031918.html git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191890 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/clang/AST/Expr.h b/include/clang/AST/Expr.h index 8a884c0b2e..a53b88d613 100644 --- a/include/clang/AST/Expr.h +++ b/include/clang/AST/Expr.h @@ -3824,6 +3824,10 @@ public: return const_cast(this)->getInitializedFieldInUnion(); } void setInitializedFieldInUnion(FieldDecl *FD) { + assert((FD == 0 + || getInitializedFieldInUnion() == 0 + || getInitializedFieldInUnion() == FD) + && "Only one field of a union may be initialized at a time!"); ArrayFillerOrUnionFieldInit = FD; } diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp index afd9393123..e407253df7 100644 --- a/lib/Sema/SemaInit.cpp +++ b/lib/Sema/SemaInit.cpp @@ -1868,8 +1868,29 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity, // the initializer list. if (RT->getDecl()->isUnion()) { FieldIndex = 0; - if (!VerifyOnly) + if (!VerifyOnly) { + FieldDecl *CurrentField = StructuredList->getInitializedFieldInUnion(); + if (CurrentField && CurrentField != *Field) { + assert(StructuredList->getNumInits() == 1 + && "A union should never have more than one initializer!"); + + // we're about to throw away an initializer, emit warning + SemaRef.Diag(D->getFieldLoc(), + diag::warn_initializer_overrides) + << D->getSourceRange(); + Expr *ExistingInit = StructuredList->getInit(0); + SemaRef.Diag(ExistingInit->getLocStart(), + diag::note_previous_initializer) + << /*FIXME:has side effects=*/0 + << ExistingInit->getSourceRange(); + + // remove existing initializer + StructuredList->resizeInits(SemaRef.Context, 0); + StructuredList->setInitializedFieldInUnion(0); + } + StructuredList->setInitializedFieldInUnion(*Field); + } } // Make sure we can use this declaration. diff --git a/test/CodeGen/designated-initializers.c b/test/CodeGen/designated-initializers.c index b41898600b..b11c67a454 100644 --- a/test/CodeGen/designated-initializers.c +++ b/test/CodeGen/designated-initializers.c @@ -81,6 +81,63 @@ struct overwrite_string_struct5 { // CHECK: [6 x i8] c"foo\00y\00", i32 1 +// CHECK: @u1 = {{.*}} { i32 65535 } +union u_FFFF { char c; long l; } u1 = { .l = 0xFFFF }; + + +/// PR16644 +typedef union u_16644 { + struct s_16644 { + int zero; + int one; + int two; + int three; + } a; + int b[4]; +} union_16644_t; + +// CHECK: @union_16644_instance_0 = {{.*}} { i32 0, i32 0, i32 0, i32 3 } } +union_16644_t union_16644_instance_0 = +{ + .b[0] = 0, + .a.one = 1, + .b[2] = 2, + .a.three = 3, +}; + +// CHECK: @union_16644_instance_1 = {{.*}} [i32 10, i32 0, i32 0, i32 0] +union_16644_t union_16644_instance_1 = +{ + .a.three = 13, + .b[2] = 12, + .a.one = 11, + .b[0] = 10, +}; + +// CHECK: @union_16644_instance_2 = {{.*}} [i32 0, i32 20, i32 0, i32 0] +union_16644_t union_16644_instance_2 = +{ + .a.one = 21, + .b[1] = 20, +}; + +// CHECK: @union_16644_instance_3 = {{.*}} { i32 0, i32 31, i32 0, i32 0 } +union_16644_t union_16644_instance_3 = +{ + .b[1] = 30, + .a = { + .one = 31 + } +}; + +// CHECK: @union_16644_instance_4 = {{.*}} { i32 5, i32 2, i32 0, i32 0 } {{.*}} [i32 0, i32 4, i32 0, i32 0] +union_16644_t union_16644_instance_4[2] = +{ + [0].a.one = 2, + [1].a.zero = 3, + [0].a.zero = 5, + [1].b[1] = 4 +}; void test1(int argc, char **argv) { diff --git a/test/Sema/designated-initializers.c b/test/Sema/designated-initializers.c index 36fa559f6f..6630da67c5 100644 --- a/test/Sema/designated-initializers.c +++ b/test/Sema/designated-initializers.c @@ -137,7 +137,6 @@ void test() { }; } -// FIXME: How do we test that this initializes the long properly? union { char c; long l; } u1 = { .l = 0xFFFF }; extern float global_float; @@ -223,6 +222,55 @@ struct Enigma enigma = { }; +/// PR16644 +typedef union { + struct { + int zero; + int one; + int two; + int three; + } a; + int b[4]; +} union_16644_t; + +union_16644_t union_16644_instance_0 = +{ + .b[0] = 0, // expected-note{{previous}} + .a.one = 1, // expected-warning{{overrides}} expected-note{{previous}} + .b[2] = 2, // expected-warning{{overrides}} expected-note{{previous}} + .a.three = 3, // expected-warning{{overrides}} +}; + +union_16644_t union_16644_instance_1 = +{ + .a.three = 13, // expected-note{{previous}} + .b[2] = 12, // expected-warning{{overrides}} expected-note{{previous}} + .a.one = 11, // expected-warning{{overrides}} expected-note{{previous}} + .b[0] = 10, // expected-warning{{overrides}} +}; + +union_16644_t union_16644_instance_2 = +{ + .a.one = 21, // expected-note{{previous}} + .b[1] = 20, // expected-warning{{overrides}} +}; + +union_16644_t union_16644_instance_3 = +{ + .b[1] = 30, // expected-note{{previous}} + .a = { // expected-warning{{overrides}} + .one = 31 + } +}; + +union_16644_t union_16644_instance_4[2] = +{ + [0].a.one = 2, + [1].a.zero = 3,// expected-note{{previous}} + [0].a.zero = 5, + [1].b[1] = 4 // expected-warning{{overrides}} +}; + /// PR4073 /// Should use evaluate to fold aggressively and emit a warning if not an ice. extern int crazy_x;