Implement p0292r2 (constexpr if), a likely C++1z feature.

llvm-svn: 273602

1 files changed, 31 insertions, 0 deletions

diff --git a/clang/lib/Sema/JumpDiagnostics.cpp b/clang/lib/Sema/JumpDiagnostics.cpp
index 500e761bf16..bd541397e1a 100644
--- a/clang/lib/Sema/JumpDiagnostics.cpp
+++ b/clang/lib/Sema/JumpDiagnostics.cpp
@@ -319,6 +319,37 @@ void JumpScopeChecker::BuildScopeInformation(Stmt *S,
     Jumps.push_back(S);
     break;
 
+  case Stmt::IfStmtClass: {
+    IfStmt *IS = cast<IfStmt>(S);
+    if (!IS->isConstexpr())
+      break;
+
+    if (VarDecl *Var = IS->getConditionVariable())
+      BuildScopeInformation(Var, ParentScope);
+
+    // Cannot jump into the middle of the condition.
+    unsigned NewParentScope = Scopes.size();
+    Scopes.push_back(GotoScope(ParentScope,
+                               diag::note_protected_by_constexpr_if, 0,
+                               IS->getLocStart()));
+    BuildScopeInformation(IS->getCond(), NewParentScope);
+
+    // Jumps into either arm of an 'if constexpr' are not allowed.
+    NewParentScope = Scopes.size();
+    Scopes.push_back(GotoScope(ParentScope,
+                               diag::note_protected_by_constexpr_if, 0,
+                               IS->getLocStart()));
+    BuildScopeInformation(IS->getThen(), NewParentScope);
+    if (Stmt *Else = IS->getElse()) {
+      NewParentScope = Scopes.size();
+      Scopes.push_back(GotoScope(ParentScope,
+                                 diag::note_protected_by_constexpr_if, 0,
+                                 IS->getLocStart()));
+      BuildScopeInformation(Else, NewParentScope);
+    }
+    return;
+  }
+
   case Stmt::CXXTryStmtClass: {
     CXXTryStmt *TS = cast<CXXTryStmt>(S);
     {