P0305R0: Semantic analysis and code generation for C++17 init-statement for 'if' and 'switch':

  if (stmt; condition) { ... }

Patch by Anton Bikineev! Some minor formatting and comment tweets by me.

llvm-svn: 275350

1 files changed, 19 insertions, 6 deletions

diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 825a2008d4e..d9ad79f75de 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -1174,9 +1174,9 @@ public:
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildIfStmt(SourceLocation IfLoc, bool IsConstexpr,
-                           Sema::ConditionResult Cond, Stmt *Then,
+                           Sema::ConditionResult Cond, Stmt *Init, Stmt *Then,
                            SourceLocation ElseLoc, Stmt *Else) {
-    return getSema().ActOnIfStmt(IfLoc, IsConstexpr, nullptr, Cond, Then,
+    return getSema().ActOnIfStmt(IfLoc, IsConstexpr, Init, Cond, Then,
                                  ElseLoc, Else);
   }
 
@@ -1184,9 +1184,9 @@ public:
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
-  StmtResult RebuildSwitchStmtStart(SourceLocation SwitchLoc,
+  StmtResult RebuildSwitchStmtStart(SourceLocation SwitchLoc, Stmt *Init,
                                     Sema::ConditionResult Cond) {
-    return getSema().ActOnStartOfSwitchStmt(SwitchLoc, nullptr, Cond);
+    return getSema().ActOnStartOfSwitchStmt(SwitchLoc, Init, Cond);
   }
 
   /// \brief Attach the body to the switch statement.
@@ -6266,6 +6266,11 @@ StmtResult TreeTransform<Derived>::TransformAttributedStmt(AttributedStmt *S) {
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformIfStmt(IfStmt *S) {
+  // Transform the initialization statement
+  StmtResult Init = getDerived().TransformStmt(S->getInit());
+  if (Init.isInvalid())
+    return StmtError();
+
   // Transform the condition
   Sema::ConditionResult Cond = getDerived().TransformCondition(
       S->getIfLoc(), S->getConditionVariable(), S->getCond(),
@@ -6298,18 +6303,25 @@ TreeTransform<Derived>::TransformIfStmt(IfStmt *S) {
   }
 
   if (!getDerived().AlwaysRebuild() &&
+      Init.get() == S->getInit() &&
       Cond.get() == std::make_pair(S->getConditionVariable(), S->getCond()) &&
       Then.get() == S->getThen() &&
       Else.get() == S->getElse())
     return S;
 
   return getDerived().RebuildIfStmt(S->getIfLoc(), S->isConstexpr(), Cond,
-                                    Then.get(), S->getElseLoc(), Else.get());
+                                    Init.get(), Then.get(), S->getElseLoc(),
+                                    Else.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformSwitchStmt(SwitchStmt *S) {
+  // Transform the initialization statement
+  StmtResult Init = getDerived().TransformStmt(S->getInit());
+  if (Init.isInvalid())
+    return StmtError();
+
   // Transform the condition.
   Sema::ConditionResult Cond = getDerived().TransformCondition(
       S->getSwitchLoc(), S->getConditionVariable(), S->getCond(),
@@ -6319,7 +6331,8 @@ TreeTransform<Derived>::TransformSwitchStmt(SwitchStmt *S) {
 
   // Rebuild the switch statement.
   StmtResult Switch
-    = getDerived().RebuildSwitchStmtStart(S->getSwitchLoc(), Cond);
+    = getDerived().RebuildSwitchStmtStart(S->getSwitchLoc(),
+                                          S->getInit(), Cond);
   if (Switch.isInvalid())
     return StmtError();