riccibruno created this revision.
riccibruno added reviewers: rsmith, aaron.ballman, Rakete1111.
riccibruno added a project: clang.
Herald added a subscriber: cfe-commits.
In C++17 the postfix-expression of a call expression is sequenced before each
expression in the expression-list and any default argument.
Repository:
rC Clang
https://reviews.llvm.org/D58579
Files:
include/clang/AST/Expr.h
lib/Sema/SemaChecking.cpp
test/SemaCXX/warn-unsequenced.cpp
Index: test/SemaCXX/warn-unsequenced.cpp
===================================================================
--- test/SemaCXX/warn-unsequenced.cpp
+++ test/SemaCXX/warn-unsequenced.cpp
@@ -15,7 +15,6 @@
int n;
};
-// TODO: Implement the C++17 sequencing rules.
void test() {
int a;
int xs[10];
@@ -256,6 +255,17 @@
p[i++] = (i = 42); // cxx11-warning {{multiple unsequenced modifications to 'i'}}
p++[i++] = (i = p ? i++ : i++); // cxx11-warning {{unsequenced modification and access to 'p'}}
// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
+
+ (i++, f)(i++, 42); // cxx11-warning {{multiple unsequenced modifications to 'i'}}
+ (i++ + i++, f)(42, 42); // cxx11-warning {{multiple unsequenced modifications to 'i'}}
+ // cxx17-warning@-1 {{multiple unsequenced modifications to 'i'}}
+ int (*pf)(int, int);
+ (pf = f)(pf != nullptr, pf != nullptr); // cxx11-warning {{unsequenced modification and access to 'pf'}}
+ pf((pf = f) != nullptr, 42); // cxx11-warning {{unsequenced modification and access to 'pf'}}
+ f((pf = f, 42), (pf = f, 42)); // cxx11-warning {{multiple unsequenced modifications to 'pf'}}
+ // cxx17-warning@-1 {{multiple unsequenced modifications to 'pf'}}
+ pf((pf = f) != nullptr, pf == nullptr); // cxx11-warning {{unsequenced modification and access to 'pf'}}
+ // cxx17-warning@-1 {{unsequenced modification and access to 'pf'}}
}
namespace members {
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -12490,6 +12490,11 @@
}
void VisitCallExpr(const CallExpr *CE) {
+ // FIXME: CXXNewExpr and CXXDeleteExpr implicitly call functions.
+
+ if (CE->isUnevaluatedBuiltinCall(Context))
+ return;
+
// C++11 [intro.execution]p15:
// When calling a function [...], every value computation and side effect
// associated with any argument expression, or with the postfix expression
@@ -12497,9 +12502,50 @@
// expression or statement in the body of the function [and thus before
// the value computation of its result].
SequencedSubexpression Sequenced(*this);
- Base::VisitCallExpr(CE);
- // FIXME: CXXNewExpr and CXXDeleteExpr implicitly call functions.
+ // C++17 [expr.call]p5
+ // The postfix-expression is sequenced before each expression in the
+ // expression-list and any default argument. [...]
+ SequenceTree::Seq CalleeRegion;
+ SequenceTree::Seq OtherRegion;
+ if (SemaRef.getLangOpts().CPlusPlus17) {
+ CalleeRegion = Tree.allocate(Region);
+ OtherRegion = Tree.allocate(Region);
+ } else {
+ CalleeRegion = Region;
+ OtherRegion = Region;
+ }
+ SequenceTree::Seq OldRegion = Region;
+
+ llvm::ArrayRef<Stmt *> SubExprs = CE->getRawSubExprs();
+ const Stmt *const *SubExpr = SubExprs.begin();
+ const Stmt *const *EndExpr = SubExprs.end();
+
+ // Visit the callee expression first.
+ Region = CalleeRegion;
+ if (SemaRef.getLangOpts().CPlusPlus17) {
+ SequencedSubexpression Sequenced(*this);
+ Visit(cast<Expr>(*SubExpr));
+ } else {
+ Visit(cast<Expr>(*SubExpr));
+ }
+ assert(cast<Expr>(*SubExpr) == CE->getCallee() &&
+ "The first sub-expression of the call expression is"
+ " assumed to be the callee expression!");
+ ++SubExpr;
+
+ // Then visit the argument expressions. We are not able to use
+ // CallExpr::arguments since we also need to visit the pre-argument
+ // expressions.
+ Region = OtherRegion;
+ for (; SubExpr != EndExpr; ++SubExpr)
+ Visit(cast<Expr>(*SubExpr));
+
+ Region = OldRegion;
+ if (SemaRef.getLangOpts().CPlusPlus17) {
+ Tree.merge(CalleeRegion);
+ Tree.merge(OtherRegion);
+ }
}
void VisitCXXConstructExpr(const CXXConstructExpr *CCE) {
Index: include/clang/AST/Expr.h
===================================================================
--- include/clang/AST/Expr.h
+++ include/clang/AST/Expr.h
@@ -2639,7 +2639,7 @@
/// a CallExpr without going through the slower virtual child_iterator
/// interface. This provides efficient reverse iteration of the
/// subexpressions. This is currently used for CFG construction.
- ArrayRef<Stmt *> getRawSubExprs() {
+ ArrayRef<Stmt *> getRawSubExprs() const {
return llvm::makeArrayRef(getTrailingStmts(),
PREARGS_START + getNumPreArgs() + getNumArgs());
}
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