void created this revision. void added reviewers: stuij, MaskRay, aaron.ballman. Herald added a subscriber: StephenFan. Herald added a project: All. void requested review of this revision. Herald added a project: clang. Herald added a subscriber: cfe-commits.
If a randomized structure has an initializer with a dedicated initializer in it, the field initialzed by that dedicated initializer may end up at the end of the RecordDecl. This however may skip the random layout initization check. struct t { int a, b, c, d, e; } x = { .a = 2, 4, 5, 6 }; Let's say that "a" is lands as the last field after randomization. The call to CheckDesignatedInitializer sets the iterator to the end of the initializer list. During the next iteration of the initializer list check, it detects that and fails to issue the error about initializing a randomized struct with non-designated initializer. Instead, it issues an error about "excess elements in struct initializer", which is confusing under these circumstances. Repository: rG LLVM Github Monorepo https://reviews.llvm.org/D124694 Files: clang/lib/Sema/SemaInit.cpp clang/test/Sema/init-randomized-struct.c Index: clang/test/Sema/init-randomized-struct.c =================================================================== --- clang/test/Sema/init-randomized-struct.c +++ clang/test/Sema/init-randomized-struct.c @@ -1,4 +1,4 @@ -// RUN: %clang_cc1 -triple=x86_64-unknown-linux -frandomize-layout-seed=1234567890abcdef \ +// RUN: %clang_cc1 -triple=x86_64-unknown-linux -frandomize-layout-seed=1234567890abcded \ // RUN: -verify -fsyntax-only -Werror %s // Initializing a randomized structure requires a designated initializer, Index: clang/lib/Sema/SemaInit.cpp =================================================================== --- clang/lib/Sema/SemaInit.cpp +++ clang/lib/Sema/SemaInit.cpp @@ -2170,11 +2170,6 @@ continue; } - if (Field == FieldEnd) { - // We've run out of fields. We're done. - break; - } - // Check if this is an initializer of forms: // // struct foo f = {}; @@ -2204,6 +2199,11 @@ break; } + if (Field == FieldEnd) { + // We've run out of fields. We're done. + break; + } + // We've already initialized a member of a union. We're done. if (InitializedSomething && DeclType->isUnionType()) break;
Index: clang/test/Sema/init-randomized-struct.c =================================================================== --- clang/test/Sema/init-randomized-struct.c +++ clang/test/Sema/init-randomized-struct.c @@ -1,4 +1,4 @@ -// RUN: %clang_cc1 -triple=x86_64-unknown-linux -frandomize-layout-seed=1234567890abcdef \ +// RUN: %clang_cc1 -triple=x86_64-unknown-linux -frandomize-layout-seed=1234567890abcded \ // RUN: -verify -fsyntax-only -Werror %s // Initializing a randomized structure requires a designated initializer, Index: clang/lib/Sema/SemaInit.cpp =================================================================== --- clang/lib/Sema/SemaInit.cpp +++ clang/lib/Sema/SemaInit.cpp @@ -2170,11 +2170,6 @@ continue; } - if (Field == FieldEnd) { - // We've run out of fields. We're done. - break; - } - // Check if this is an initializer of forms: // // struct foo f = {}; @@ -2204,6 +2199,11 @@ break; } + if (Field == FieldEnd) { + // We've run out of fields. We're done. + break; + } + // We've already initialized a member of a union. We're done. if (InitializedSomething && DeclType->isUnionType()) break;
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