[clang] Warning for incorrect useof 'pure' attribute (PR #78200)
via cfe-commits
cfe-commits at lists.llvm.org
Wed Jan 17 08:28:37 PST 2024
https://github.com/kelbon updated https://github.com/llvm/llvm-project/pull/78200
>From b080d04eb30254502ccd5d59d76b5197db1fa88d Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Mon, 15 Jan 2024 22:24:34 +0400
Subject: [PATCH 1/8] add warning and test
---
clang/include/clang/Basic/DiagnosticGroups.td | 1 +
clang/include/clang/Basic/DiagnosticSemaKinds.td | 7 +++++++
clang/lib/Sema/SemaDecl.cpp | 7 +++++++
clang/test/Sema/incorrect_pure.cpp | 7 +++++++
4 files changed, 22 insertions(+)
create mode 100644 clang/test/Sema/incorrect_pure.cpp
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 6765721ae7002c1..9fcf2be2e45458e 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -414,6 +414,7 @@ def : DiagGroup<"c++2a-compat", [CXX20Compat]>;
def : DiagGroup<"c++2a-compat-pedantic", [CXX20CompatPedantic]>;
def ExitTimeDestructors : DiagGroup<"exit-time-destructors">;
+def IncorrectAttributeUsage : DiagGroup<"incorrect-attribute-usage">;
def FlexibleArrayExtensions : DiagGroup<"flexible-array-extensions">;
def FourByteMultiChar : DiagGroup<"four-char-constants">;
def GlobalConstructors : DiagGroup<"global-constructors"> {
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 414779a7970ab8e..0ad3ea64503d81e 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -692,6 +692,13 @@ def warn_maybe_falloff_nonvoid_function : Warning<
def warn_falloff_nonvoid_function : Warning<
"non-void function does not return a value">,
InGroup<ReturnType>;
+def warn_pure_attr_on_cxx_constructor : Warning<
+ "constructor cannot be 'pure' (undefined behavior)">,
+ InGroup<IncorrectAttributeUsage>;
+def warn_pure_function_returns_void : Warning<
+ "'pure' attribute on function returning 'void'">,
+ InGroup<IncorrectAttributeUsage>;
+
def err_maybe_falloff_nonvoid_block : Error<
"non-void block does not return a value in all control paths">;
def err_falloff_nonvoid_block : Error<
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 4e7049571eeb7a3..e340028703b3b31 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -11889,6 +11889,13 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
NewFD->setInvalidDecl();
}
+ if (NewFD->hasAttr<PureAttr>() || NewFD->hasAttr<ConstAttr>()) {
+ if (isa_and_nonnull<CXXConstructorDecl>(NewFD))
+ Diag(NewFD->getLocation(), diag::warn_pure_attr_on_cxx_constructor);
+ else if (NewFD->getReturnType()->isVoidType())
+ Diag(NewFD->getLocation(), diag::warn_pure_function_returns_void);
+ }
+
// C++11 [dcl.constexpr]p8:
// A constexpr specifier for a non-static member function that is not
// a constructor declares that member function to be const.
diff --git a/clang/test/Sema/incorrect_pure.cpp b/clang/test/Sema/incorrect_pure.cpp
new file mode 100644
index 000000000000000..ce02309f0863863
--- /dev/null
+++ b/clang/test/Sema/incorrect_pure.cpp
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+[[gnu::pure]] void foo(); // expected-warning{{'pure' attribute on function returning 'void'}}
+
+struct A {
+ [[gnu::pure]] A(); // expected-warning{{constructor cannot be 'pure' (undefined behavior)}}
+};
>From d43afccb027ea0e02c97ab9fbe55a1ad6c9d71dd Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Mon, 15 Jan 2024 22:52:23 +0400
Subject: [PATCH 2/8] use precondition: NewFD is not null
---
clang/lib/Sema/SemaDecl.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index e340028703b3b31..dcbc5c3c842cca3 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -11890,7 +11890,7 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
}
if (NewFD->hasAttr<PureAttr>() || NewFD->hasAttr<ConstAttr>()) {
- if (isa_and_nonnull<CXXConstructorDecl>(NewFD))
+ if (isa<CXXConstructorDecl>(NewFD))
Diag(NewFD->getLocation(), diag::warn_pure_attr_on_cxx_constructor);
else if (NewFD->getReturnType()->isVoidType())
Diag(NewFD->getLocation(), diag::warn_pure_function_returns_void);
>From 950ca9de1c05d561a1123c088455a3e21bd9795b Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Tue, 16 Jan 2024 00:03:47 +0400
Subject: [PATCH 3/8] fix old incorrect test
---
clang/test/SemaCXX/cxx0x-cursory-default-delete.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/test/SemaCXX/cxx0x-cursory-default-delete.cpp b/clang/test/SemaCXX/cxx0x-cursory-default-delete.cpp
index 9d68a0e5d358f67..6ae146f0d08c7d3 100644
--- a/clang/test/SemaCXX/cxx0x-cursory-default-delete.cpp
+++ b/clang/test/SemaCXX/cxx0x-cursory-default-delete.cpp
@@ -194,7 +194,7 @@ struct except_spec_d_match : except_spec_a, except_spec_b {
// gcc-compatibility: allow attributes on default definitions
// (but not normal definitions)
struct S { S(); };
-S::S() __attribute((pure)) = default;
+S::S() __attribute((noreturn)) = default;
using size_t = decltype(sizeof(0));
void *operator new(size_t) = delete; // expected-error {{deleted definition must be first declaration}} expected-note {{implicit}}
>From 74bf7b1840cf2b20baae3348c0e46b44a04a5408 Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Tue, 16 Jan 2024 11:29:49 +0400
Subject: [PATCH 4/8] fix another old test
---
clang/test/SemaCXX/warn-unused-value-cxx11.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/test/SemaCXX/warn-unused-value-cxx11.cpp b/clang/test/SemaCXX/warn-unused-value-cxx11.cpp
index a6f41c3fd6b3b2a..687278a98f4e1a4 100644
--- a/clang/test/SemaCXX/warn-unused-value-cxx11.cpp
+++ b/clang/test/SemaCXX/warn-unused-value-cxx11.cpp
@@ -1,6 +1,6 @@
// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -Wunused-value %s
-void f() __attribute__((const));
+int f() __attribute__((const));
namespace PR18571 {
// Unevaluated contexts should not trigger unused result warnings.
>From bde11e037554481f90852e2ecd72fea9a3faffe6 Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Tue, 16 Jan 2024 14:52:19 +0400
Subject: [PATCH 5/8] fix all old tests
---
clang/test/Analysis/call-invalidation.cpp | 8 ++++----
clang/test/CodeGen/pragma-weak.c | 6 +++---
clang/test/Interpreter/disambiguate-decl-stmt.cpp | 4 ++--
3 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/clang/test/Analysis/call-invalidation.cpp b/clang/test/Analysis/call-invalidation.cpp
index ef6505e19cf803f..727217f228b0542 100644
--- a/clang/test/Analysis/call-invalidation.cpp
+++ b/clang/test/Analysis/call-invalidation.cpp
@@ -90,8 +90,8 @@ void testConstReferenceStruct() {
}
-void usePointerPure(int * const *) __attribute__((pure));
-void usePointerConst(int * const *) __attribute__((const));
+int usePointerPure(int * const *) __attribute__((pure));
+int usePointerConst(int * const *) __attribute__((const));
void testPureConst() {
extern int global;
@@ -104,11 +104,11 @@ void testPureConst() {
clang_analyzer_eval(x == 42); // expected-warning{{TRUE}}
clang_analyzer_eval(global == -5); // expected-warning{{TRUE}}
- usePointerPure(&p);
+ (void)usePointerPure(&p);
clang_analyzer_eval(x == 42); // expected-warning{{TRUE}}
clang_analyzer_eval(global == -5); // expected-warning{{TRUE}}
- usePointerConst(&p);
+ (void)usePointerConst(&p);
clang_analyzer_eval(x == 42); // expected-warning{{TRUE}}
clang_analyzer_eval(global == -5); // expected-warning{{TRUE}}
diff --git a/clang/test/CodeGen/pragma-weak.c b/clang/test/CodeGen/pragma-weak.c
index 52328bf9ff1be75..d4011628bda7f12 100644
--- a/clang/test/CodeGen/pragma-weak.c
+++ b/clang/test/CodeGen/pragma-weak.c
@@ -16,7 +16,7 @@
// CHECK-DAG: @declfirstattr = weak{{.*}} alias void (), ptr @__declfirstattr
// CHECK-DAG: @mix2 = weak{{.*}} alias void (), ptr @__mix2
// CHECK-DAG: @a1 = weak{{.*}} alias void (), ptr @__a1
-// CHECK-DAG: @xxx = weak{{.*}} alias void (), ptr @__xxx
+// CHECK-DAG: @xxx = weak{{.*}} alias int (), ptr @__xxx
// CHECK-DAG: @undecfunc_alias1 = weak{{.*}} alias void (), ptr @undecfunc
// CHECK-DAG: @undecfunc_alias2 = weak{{.*}} alias void (), ptr @undecfunc
// CHECK-DAG: @undecfunc_alias3 = weak{{.*}} alias void (), ptr @undecfunc
@@ -137,8 +137,8 @@ void __a1(void) {}
// CHECK: define{{.*}} void @__a1() [[NI:#[0-9]+]]
#pragma weak xxx = __xxx
-__attribute((pure,noinline,const)) void __xxx(void) { }
-// CHECK: void @__xxx() [[RN:#[0-9]+]]
+__attribute((pure,noinline,const)) int __xxx(void) { return 0; }
+// CHECK: int @__xxx() [[RN:#[0-9]+]]
///////////// PR28611: Try multiple aliases of same undeclared symbol or alias
#pragma weak undecfunc_alias1 = undecfunc
diff --git a/clang/test/Interpreter/disambiguate-decl-stmt.cpp b/clang/test/Interpreter/disambiguate-decl-stmt.cpp
index a49d7013c540ac2..1f4d5e267288bc3 100644
--- a/clang/test/Interpreter/disambiguate-decl-stmt.cpp
+++ b/clang/test/Interpreter/disambiguate-decl-stmt.cpp
@@ -95,10 +95,10 @@ Ns::Ns::Fs();
Ns::Ns::Ns();
struct Attrs1 { Attrs1(); };
-Attrs1::Attrs1() __attribute((pure)) = default;
+Attrs1::Attrs1() __attribute((noreturn)) = default;
struct Attrs2 { Attrs2(); };
-__attribute((pure)) Attrs2::Attrs2() = default;
+__attribute((noreturn)) Attrs2::Attrs2() = default;
// Extra semicolon
namespace N {};
>From 35f854e8238207fb5463e9990f2cac27907f8886 Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Wed, 17 Jan 2024 15:00:39 +0400
Subject: [PATCH 6/8] release notes, update warning message, handle pure &&
const declarations
---
clang/docs/ReleaseNotes.rst | 3 +-
clang/include/clang/Basic/DiagnosticGroups.td | 1 -
.../clang/Basic/DiagnosticSemaKinds.td | 11 ++++---
clang/lib/Sema/SemaDecl.cpp | 32 +++++++++++++++----
clang/test/CodeGen/pragma-weak.c | 6 ++--
clang/test/Sema/incorrect_pure.cpp | 8 ++++-
6 files changed, 45 insertions(+), 16 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 7e130304c5c08f8..def67063ad2d135 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -560,7 +560,8 @@ Improvements to Clang's diagnostics
- Clang now diagnoses unexpanded packs within the template argument lists of function template specializations.
- Clang now diagnoses attempts to bind a bitfield to an NTTP of a reference type as erroneous
converted constant expression and not as a reference to subobject.
-
+- Clang now diagnoses incorrect usage of 'const' and 'pure' attributes (``-Wincorrect-pure-usage``),
+ also ``-Wignored-attributes`` diagnoses more cases.
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 9fcf2be2e45458e..6765721ae7002c1 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -414,7 +414,6 @@ def : DiagGroup<"c++2a-compat", [CXX20Compat]>;
def : DiagGroup<"c++2a-compat-pedantic", [CXX20CompatPedantic]>;
def ExitTimeDestructors : DiagGroup<"exit-time-destructors">;
-def IncorrectAttributeUsage : DiagGroup<"incorrect-attribute-usage">;
def FlexibleArrayExtensions : DiagGroup<"flexible-array-extensions">;
def FourByteMultiChar : DiagGroup<"four-char-constants">;
def GlobalConstructors : DiagGroup<"global-constructors"> {
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0ad3ea64503d81e..f71501994973573 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -692,12 +692,15 @@ def warn_maybe_falloff_nonvoid_function : Warning<
def warn_falloff_nonvoid_function : Warning<
"non-void function does not return a value">,
InGroup<ReturnType>;
+def warn_const_attr_with_pure_attr : Warning<
+ "'const' attribute imposes greater restrictions than 'pure', 'pure' attribute ignored">,
+ InGroup<IgnoredAttributes>;
def warn_pure_attr_on_cxx_constructor : Warning<
- "constructor cannot be 'pure' (undefined behavior)">,
- InGroup<IncorrectAttributeUsage>;
+ "constructor cannot be '%select{pure|const}0', attribute ignored">,
+ InGroup<IgnoredAttributes>;
def warn_pure_function_returns_void : Warning<
- "'pure' attribute on function returning 'void'">,
- InGroup<IncorrectAttributeUsage>;
+ "'%select{pure|const}0' attribute on function returning 'void'">,
+ InGroup<DiagGroup<"incorrect-pure-usage">>;
def err_maybe_falloff_nonvoid_block : Error<
"non-void block does not return a value in all control paths">;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index dcbc5c3c842cca3..a0083c841c765fc 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -11792,6 +11792,31 @@ static bool CheckMultiVersionFunction(Sema &S, FunctionDecl *NewFD,
OldDecl, Previous);
}
+static void CheckFunctionDeclarationAttributesUsage(Sema &S, FunctionDecl *NewFD) {
+ const bool is_pure = NewFD->hasAttr<PureAttr>();
+ const bool is_const = NewFD->hasAttr<ConstAttr>();
+
+ if (is_pure && is_const) {
+ S.Diag(NewFD->getLocation(), diag::warn_const_attr_with_pure_attr);
+ NewFD->dropAttr<PureAttr>();
+ }
+ if (is_pure || is_const) {
+ if (isa<CXXConstructorDecl>(NewFD)) {
+ // 'pure' constructor is an insidious error:
+ // while constructor semantically 'returns' object
+ // but it should modify memory by implicit 'this' pointer
+ S.Diag(NewFD->getLocation(), diag::warn_pure_attr_on_cxx_constructor)
+ << (is_const ? 1 : 0);
+ // ignore attributes is this case (do not produce UB)
+ NewFD->dropAttr<PureAttr>();
+ NewFD->dropAttr<ConstAttr>();
+ } else if (NewFD->getReturnType()->isVoidType()) {
+ S.Diag(NewFD->getLocation(), diag::warn_pure_function_returns_void)
+ << (is_const ? 1 : 0);
+ }
+ }
+}
+
/// Perform semantic checking of a new function declaration.
///
/// Performs semantic analysis of the new function declaration
@@ -11889,12 +11914,7 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
NewFD->setInvalidDecl();
}
- if (NewFD->hasAttr<PureAttr>() || NewFD->hasAttr<ConstAttr>()) {
- if (isa<CXXConstructorDecl>(NewFD))
- Diag(NewFD->getLocation(), diag::warn_pure_attr_on_cxx_constructor);
- else if (NewFD->getReturnType()->isVoidType())
- Diag(NewFD->getLocation(), diag::warn_pure_function_returns_void);
- }
+ CheckFunctionDeclarationAttributesUsage(*this, NewFD);
// C++11 [dcl.constexpr]p8:
// A constexpr specifier for a non-static member function that is not
diff --git a/clang/test/CodeGen/pragma-weak.c b/clang/test/CodeGen/pragma-weak.c
index d4011628bda7f12..ea508a485ef6121 100644
--- a/clang/test/CodeGen/pragma-weak.c
+++ b/clang/test/CodeGen/pragma-weak.c
@@ -16,7 +16,7 @@
// CHECK-DAG: @declfirstattr = weak{{.*}} alias void (), ptr @__declfirstattr
// CHECK-DAG: @mix2 = weak{{.*}} alias void (), ptr @__mix2
// CHECK-DAG: @a1 = weak{{.*}} alias void (), ptr @__a1
-// CHECK-DAG: @xxx = weak{{.*}} alias int (), ptr @__xxx
+// CHECK-DAG: @xxx = weak{{.*}} alias i32 (), ptr @__xxx
// CHECK-DAG: @undecfunc_alias1 = weak{{.*}} alias void (), ptr @undecfunc
// CHECK-DAG: @undecfunc_alias2 = weak{{.*}} alias void (), ptr @undecfunc
// CHECK-DAG: @undecfunc_alias3 = weak{{.*}} alias void (), ptr @undecfunc
@@ -137,8 +137,8 @@ void __a1(void) {}
// CHECK: define{{.*}} void @__a1() [[NI:#[0-9]+]]
#pragma weak xxx = __xxx
-__attribute((pure,noinline,const)) int __xxx(void) { return 0; }
-// CHECK: int @__xxx() [[RN:#[0-9]+]]
+__attribute((noinline,const)) int __xxx(void) { return 0; }
+// CHECK: i32 @__xxx() [[RN:#[0-9]+]]
///////////// PR28611: Try multiple aliases of same undeclared symbol or alias
#pragma weak undecfunc_alias1 = undecfunc
diff --git a/clang/test/Sema/incorrect_pure.cpp b/clang/test/Sema/incorrect_pure.cpp
index ce02309f0863863..a0908907bc3769a 100644
--- a/clang/test/Sema/incorrect_pure.cpp
+++ b/clang/test/Sema/incorrect_pure.cpp
@@ -2,6 +2,12 @@
[[gnu::pure]] void foo(); // expected-warning{{'pure' attribute on function returning 'void'}}
+[[gnu::const]] void bar(); // expected-warning{{'const' attribute on function returning 'void'}}
struct A {
- [[gnu::pure]] A(); // expected-warning{{constructor cannot be 'pure' (undefined behavior)}}
+ [[gnu::pure]] A(); // expected-warning{{constructor cannot be 'pure', attribute ignored"}}
+
+ [[gnu::const]] A(int); // expected-warning{{constructor cannot be 'const', attribute ignored"}}
+ [[gnu::pure]] ~A(); // expected-warning{{'pure' attribute on function returning 'void'}}
+
+ [[gnu::const]] [[gnu::pure]] int m(); // expected-warning{{'const' attribute imposes greater restrictions than 'pure', 'pure' attribute ignored}}
};
>From 88dc26f44c786113f8a0cacb48bc050c019e5705 Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Wed, 17 Jan 2024 15:18:05 +0400
Subject: [PATCH 7/8] format
---
clang/lib/Sema/SemaDecl.cpp | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index a0083c841c765fc..0e33504701edb4c 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -11792,7 +11792,8 @@ static bool CheckMultiVersionFunction(Sema &S, FunctionDecl *NewFD,
OldDecl, Previous);
}
-static void CheckFunctionDeclarationAttributesUsage(Sema &S, FunctionDecl *NewFD) {
+static void CheckFunctionDeclarationAttributesUsage(Sema &S,
+ FunctionDecl *NewFD) {
const bool is_pure = NewFD->hasAttr<PureAttr>();
const bool is_const = NewFD->hasAttr<ConstAttr>();
@@ -11806,13 +11807,13 @@ static void CheckFunctionDeclarationAttributesUsage(Sema &S, FunctionDecl *NewFD
// while constructor semantically 'returns' object
// but it should modify memory by implicit 'this' pointer
S.Diag(NewFD->getLocation(), diag::warn_pure_attr_on_cxx_constructor)
- << (is_const ? 1 : 0);
+ << (is_const ? 1 : 0);
// ignore attributes is this case (do not produce UB)
NewFD->dropAttr<PureAttr>();
NewFD->dropAttr<ConstAttr>();
} else if (NewFD->getReturnType()->isVoidType()) {
S.Diag(NewFD->getLocation(), diag::warn_pure_function_returns_void)
- << (is_const ? 1 : 0);
+ << (is_const ? 1 : 0);
}
}
}
>From 0cc046cf509c32de5619792e45ada7ea37942685 Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Wed, 17 Jan 2024 20:28:23 +0400
Subject: [PATCH 8/8] handle constructors, functions and destructors same way
as gcc does
---
clang/docs/ReleaseNotes.rst | 2 +-
.../clang/Basic/DiagnosticSemaKinds.td | 9 +++-----
clang/lib/Sema/SemaDecl.cpp | 22 +++++++------------
clang/test/Sema/incorrect_pure.cpp | 11 +++++-----
4 files changed, 18 insertions(+), 26 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index def67063ad2d135..755352bd7ba63c8 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -560,7 +560,7 @@ Improvements to Clang's diagnostics
- Clang now diagnoses unexpanded packs within the template argument lists of function template specializations.
- Clang now diagnoses attempts to bind a bitfield to an NTTP of a reference type as erroneous
converted constant expression and not as a reference to subobject.
-- Clang now diagnoses incorrect usage of 'const' and 'pure' attributes (``-Wincorrect-pure-usage``),
+- Clang now diagnoses incorrect usage of ``const`` and ``pure`` attributes (``-Wincorrect-pure-usage``),
also ``-Wignored-attributes`` diagnoses more cases.
Improvements to Clang's time-trace
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index f71501994973573..7b603273a878b50 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -693,14 +693,11 @@ def warn_falloff_nonvoid_function : Warning<
"non-void function does not return a value">,
InGroup<ReturnType>;
def warn_const_attr_with_pure_attr : Warning<
- "'const' attribute imposes greater restrictions than 'pure', 'pure' attribute ignored">,
- InGroup<IgnoredAttributes>;
-def warn_pure_attr_on_cxx_constructor : Warning<
- "constructor cannot be '%select{pure|const}0', attribute ignored">,
+ "'const' attribute imposes more restrictions, 'pure' attribute ignored">,
InGroup<IgnoredAttributes>;
def warn_pure_function_returns_void : Warning<
- "'%select{pure|const}0' attribute on function returning 'void'">,
- InGroup<DiagGroup<"incorrect-pure-usage">>;
+ "'%select{pure|const}0' attribute on function returning 'void', attribute ignored">,
+ InGroup<IgnoredAttributes>;
def err_maybe_falloff_nonvoid_block : Error<
"non-void block does not return a value in all control paths">;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 0e33504701edb4c..041ef468cfe11db 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -11794,26 +11794,20 @@ static bool CheckMultiVersionFunction(Sema &S, FunctionDecl *NewFD,
static void CheckFunctionDeclarationAttributesUsage(Sema &S,
FunctionDecl *NewFD) {
- const bool is_pure = NewFD->hasAttr<PureAttr>();
- const bool is_const = NewFD->hasAttr<ConstAttr>();
+ bool IsPure = NewFD->hasAttr<PureAttr>();
+ bool IsConst = NewFD->hasAttr<ConstAttr>();
- if (is_pure && is_const) {
+ if (IsPure && IsConst) {
S.Diag(NewFD->getLocation(), diag::warn_const_attr_with_pure_attr);
NewFD->dropAttr<PureAttr>();
}
- if (is_pure || is_const) {
- if (isa<CXXConstructorDecl>(NewFD)) {
- // 'pure' constructor is an insidious error:
- // while constructor semantically 'returns' object
- // but it should modify memory by implicit 'this' pointer
- S.Diag(NewFD->getLocation(), diag::warn_pure_attr_on_cxx_constructor)
- << (is_const ? 1 : 0);
- // ignore attributes is this case (do not produce UB)
+ if (IsPure || IsConst) {
+ // constructors and destructors also functions which returns void
+ if (NewFD->getReturnType()->isVoidType()) {
+ S.Diag(NewFD->getLocation(), diag::warn_pure_function_returns_void)
+ << IsConst;
NewFD->dropAttr<PureAttr>();
NewFD->dropAttr<ConstAttr>();
- } else if (NewFD->getReturnType()->isVoidType()) {
- S.Diag(NewFD->getLocation(), diag::warn_pure_function_returns_void)
- << (is_const ? 1 : 0);
}
}
}
diff --git a/clang/test/Sema/incorrect_pure.cpp b/clang/test/Sema/incorrect_pure.cpp
index a0908907bc3769a..d4257003848bbb3 100644
--- a/clang/test/Sema/incorrect_pure.cpp
+++ b/clang/test/Sema/incorrect_pure.cpp
@@ -1,13 +1,14 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
-[[gnu::pure]] void foo(); // expected-warning{{'pure' attribute on function returning 'void'}}
+[[gnu::pure]] void foo(); // expected-warning{{'pure' attribute on function returning 'void', attribute ignored}}
+
+[[gnu::const]] void bar(); // expected-warning{{'const' attribute on function returning 'void', attribute ignored}}
-[[gnu::const]] void bar(); // expected-warning{{'const' attribute on function returning 'void'}}
struct A {
- [[gnu::pure]] A(); // expected-warning{{constructor cannot be 'pure', attribute ignored"}}
+ [[gnu::pure]] A(); // expected-warning{{'pure' attribute on function returning 'void', attribute ignored}}
- [[gnu::const]] A(int); // expected-warning{{constructor cannot be 'const', attribute ignored"}}
+ [[gnu::const]] A(int); // expected-warning{{'const' attribute on function returning 'void', attribute ignored}}
[[gnu::pure]] ~A(); // expected-warning{{'pure' attribute on function returning 'void'}}
- [[gnu::const]] [[gnu::pure]] int m(); // expected-warning{{'const' attribute imposes greater restrictions than 'pure', 'pure' attribute ignored}}
+ [[gnu::const]] [[gnu::pure]] int m(); // expected-warning{{'const' attribute imposes more restrictions, 'pure' attribute ignored}}
};
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