Add [[clang::suppress(rule, ...)]] attribute
Summary:
This patch implements parsing of [[clang::suppress(rule, ...)]]
and [[gsl::suppress(rule, ...)]] attributes.
C++ Core Guidelines depend heavily on tool support for
rule enforcement. They also propose a way to suppress
warnings [1] which is by annotating any ancestor in AST
with the C++11 attribute [[gsl::suppress(rule1,...)]].
To have a mechanism to suppress non-C++ Core
Guidelines specific, an additional spelling of [[clang::suppress]]
is defined.
For example, to suppress the warning cppcoreguidelines-slicing,
one could do
```
[[clang::suppress("cppcoreguidelines-slicing")]]
void f() { ... code that does slicing ... }
```
or
```
void g() {
Derived b;
[[clang::suppress("cppcoreguidelines-slicing")]]
Base a{b};
[[clang::suppress("cppcoreguidelines-slicing")]] {
doSomething();
Base a2{b};
}
}
```
This parsing can then be used by clang-tidy, which includes multiple
C++ Core Guidelines rules, to suppress warnings (see
https://reviews.llvm.org/D24888).
For the exact naming of the rule in the attribute, there
are different possibilities, which will be defined in the
corresponding clang-tidy patch.
Currently, clang-tidy supports suppressing of warnings through "//
NOLINT" comments. There are some advantages that the attribute has:
- Suppressing specific warnings instead of all warnings
- Suppressing warnings in a block (namespace, function, compound
statement)
- Code formatting may split a statement into multiple lines,
thus a "// NOLINT" comment may be on the wrong line
I'm looking forward to your comments!
[1] https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#inforce-enforcement
Reviewers: alexfh, aaron.ballman, rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D24886
llvm-svn: 298880
diff --git a/clang/lib/Sema/SemaStmtAttr.cpp b/clang/lib/Sema/SemaStmtAttr.cpp
index 01fa856..4ee3412 100644
--- a/clang/lib/Sema/SemaStmtAttr.cpp
+++ b/clang/lib/Sema/SemaStmtAttr.cpp
@@ -53,6 +53,31 @@
return ::new (S.Context) auto(Attr);
}
+static Attr *handleSuppressAttr(Sema &S, Stmt *St, const AttributeList &A,
+ SourceRange Range) {
+ if (A.getNumArgs() < 1) {
+ S.Diag(A.getLoc(), diag::err_attribute_too_few_arguments)
+ << A.getName() << 1;
+ return nullptr;
+ }
+
+ std::vector<StringRef> DiagnosticIdentifiers;
+ for (unsigned I = 0, E = A.getNumArgs(); I != E; ++I) {
+ StringRef RuleName;
+
+ if (!S.checkStringLiteralArgumentAttr(A, I, RuleName, nullptr))
+ return nullptr;
+
+ // FIXME: Warn if the rule name is unknown. This is tricky because only
+ // clang-tidy knows about available rules.
+ DiagnosticIdentifiers.push_back(RuleName);
+ }
+
+ return ::new (S.Context) SuppressAttr(
+ A.getRange(), S.Context, DiagnosticIdentifiers.data(),
+ DiagnosticIdentifiers.size(), A.getAttributeSpellingListIndex());
+}
+
static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const AttributeList &A,
SourceRange) {
IdentifierLoc *PragmaNameLoc = A.getArgAsIdent(0);
@@ -279,6 +304,8 @@
return handleLoopHintAttr(S, St, A, Range);
case AttributeList::AT_OpenCLUnrollHint:
return handleOpenCLUnrollHint(S, St, A, Range);
+ case AttributeList::AT_Suppress:
+ return handleSuppressAttr(S, St, A, Range);
default:
// if we're here, then we parsed a known attribute, but didn't recognize
// it as a statement attribute => it is declaration attribute