Add an __assume side-effects warning
In MS-compatibility mode, we support the __assume builtin. The __assume builtin
does not evaluate its arguments, and we should issue a warning if __assume is
provided with an argument with side effects (because these effects will be
discarded).
This is similar in spirit to the warnings issued by other compilers (Intel
Diagnostic 2261, MS Compiler Warning C4557).
llvm-svn: 213266
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 7a23797..d8b801b 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -175,6 +175,10 @@
if (SemaBuiltinPrefetch(TheCall))
return ExprError();
break;
+ case Builtin::BI__assume:
+ if (SemaBuiltinAssume(TheCall))
+ return ExprError();
+ break;
case Builtin::BI__builtin_object_size:
if (SemaBuiltinConstantArgRange(TheCall, 1, 0, 3))
return ExprError();
@@ -1953,6 +1957,20 @@
return false;
}
+/// SemaBuiltinAssume - Handle __assume (MS Extension).
+// __assume does not evaluate its arguments, and should warn if its argument
+// has side effects.
+bool Sema::SemaBuiltinAssume(CallExpr *TheCall) {
+ Expr *Arg = TheCall->getArg(0);
+ if (Arg->isInstantiationDependent()) return false;
+
+ if (Arg->HasSideEffects(Context))
+ return Diag(Arg->getLocStart(), diag::warn_assume_side_effects)
+ << Arg->getSourceRange();
+
+ return false;
+}
+
/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
/// TheCall is a constant expression.
bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,