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When building the Linux kernel with -Wmissing-variable-declarations,
there are several instances of warnings around variables declared with
register storage:
arch/x86/include/asm/asm.h:208:24: warning: no previous extern declaration
for non-static variable 'current_stack_pointer'
[-Wmissing-variable-declarations]
register unsigned long current_stack_pointer asm(_ASM_SP);
^
arch/x86/include/asm/asm.h:208:10: note: declare 'static' if the variable is
not intended to be used outside of this translation unit
register unsigned long current_stack_pointer asm(_ASM_SP);
^
1 warning generated.
The suggestion is invalid, as the variable cannot have both static and
register storage. Do not emit -Wmissing-variable-declarations for
register variables.
Closes: https://github.com/llvm/llvm-project/issues/64509
Link: https://lore.kernel.org/202308081050.szew4cq5-...@intel.com/
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D157435
Files:
clang/docs/ReleaseNotes.rst
clang/lib/Sema/SemaDecl.cpp
clang/test/Sema/warn-missing-variable-declarations-register.c
Index: clang/test/Sema/warn-missing-variable-declarations-register.c
===================================================================
--- /dev/null
+++ clang/test/Sema/warn-missing-variable-declarations-register.c
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -Wmissing-variable-declarations
-fsyntax-only -verify %s
+// REQUIRES: x86-registered-target
+// expected-no-diagnostics
+
+register unsigned long current_stack_pointer asm("rsp");
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -14144,6 +14144,7 @@
var->getDeclContext()->getRedeclContext()->isFileContext() &&
var->isExternallyVisible() && var->hasLinkage() &&
!var->isInline() && !var->getDescribedVarTemplate() &&
+ var->getStorageClass() != SC_Register &&
!isa<VarTemplatePartialSpecializationDecl>(var) &&
!isTemplateInstantiation(var->getTemplateSpecializationKind()) &&
!getDiagnostics().isIgnored(diag::warn_missing_variable_declarations,
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -123,6 +123,8 @@
template-specialization function calls.
- Clang contexpr evaluator now displays notes as well as an error when a
constructor
of a base class is not called in the constructor of its derived class.
+- Clang no longer emits `-Wmissing-variable-declarations` for variables
declared
+ with the `register` storage class.
Bug Fixes in This Version
-------------------------
Index: clang/test/Sema/warn-missing-variable-declarations-register.c
===================================================================
--- /dev/null
+++ clang/test/Sema/warn-missing-variable-declarations-register.c
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -Wmissing-variable-declarations -fsyntax-only -verify %s
+// REQUIRES: x86-registered-target
+// expected-no-diagnostics
+
+register unsigned long current_stack_pointer asm("rsp");
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -14144,6 +14144,7 @@
var->getDeclContext()->getRedeclContext()->isFileContext() &&
var->isExternallyVisible() && var->hasLinkage() &&
!var->isInline() && !var->getDescribedVarTemplate() &&
+ var->getStorageClass() != SC_Register &&
!isa<VarTemplatePartialSpecializationDecl>(var) &&
!isTemplateInstantiation(var->getTemplateSpecializationKind()) &&
!getDiagnostics().isIgnored(diag::warn_missing_variable_declarations,
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -123,6 +123,8 @@
template-specialization function calls.
- Clang contexpr evaluator now displays notes as well as an error when a constructor
of a base class is not called in the constructor of its derived class.
+- Clang no longer emits `-Wmissing-variable-declarations` for variables declared
+ with the `register` storage class.
Bug Fixes in This Version
-------------------------
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