[PatternMatching] Fix pattern guards for pat id elements in structured bindings

Decouple binding creation from running sema for the structured bindings by
acting early on the pattern list. Since we now create the variables before parsing
the condition, their name is scope, available to be used from the guard condition.

Author: bcardosolopes

clang/include/clang/Sema/Sema.h

@@ -4248,7 +4248,10 @@ class Sema final {
   StmtResult ActOnStructuredBindingPattern(
       SourceLocation ColonLoc, SourceLocation LLoc, SourceLocation RLoc,
       SmallVectorImpl<Sema::ParsedPatEltResult> &PatList, Stmt *SubStmt,
-      Expr *Guard, bool ExcludedFromTypeDeduction);
+      Expr *Guard, Stmt *DecompStmt, bool ExcludedFromTypeDeduction);
+  StmtResult
+  ActOnPatternList(SmallVectorImpl<Sema::ParsedPatEltResult> &PatList,
+                   SourceLocation LLoc);
 
   ExprResult CheckPatternConstantExpr(Expr *MatchExpr,
                                       SourceLocation MatchExprLoc);

clang/lib/Parse/ParseStmt.cpp

@@ -875,7 +875,12 @@ StmtResult Parser::ParseStructuralBindingPattern(ParsedStmtContext StmtCtx) {
   SourceLocation IfLoc;
 
   ParseScope PatternScope(this, Scope::PatternScope | Scope::DeclScope, true);
-
+  StmtResult DecompDS;
+  if (ValidPatList) {
+    DecompDS = Actions.ActOnPatternList(PatList, LSquare);
+    if (DecompDS.isInvalid())
+      ValidPatList = false;
+  }
   // FIXME: retrieve constexpr information from InspectExpr
   if (Tok.is(tok::kw_if))
     if (!ParsePatternGuard(Cond, IfLoc, false /*IsConstexprIf*/))
@@ -908,7 +913,7 @@ StmtResult Parser::ParseStructuralBindingPattern(ParsedStmtContext StmtCtx) {
   if (ValidPatList)
     Res = Actions.ActOnStructuredBindingPattern(
         ArrowLoc, LSquare, RSquare, PatList, nullptr, Cond.get().second,
-        ExclaimLoc.isValid());
+        DecompDS.get(), ExclaimLoc.isValid());
 
   // Parse the statement
   //

clang/lib/Sema/SemaStmt.cpp

@@ -681,10 +681,9 @@ StmtResult Sema::ActOnExpressionPattern(SourceLocation MatchExprLoc,
   return EPS;
 }
 
-StmtResult Sema::ActOnStructuredBindingPattern(
-    SourceLocation ColonLoc, SourceLocation LLoc, SourceLocation RLoc,
-    SmallVectorImpl<Sema::ParsedPatEltResult> &PatList, Stmt *SubStmt,
-    Expr *Guard, bool ExcludedFromTypeDeduction) {
+StmtResult
+Sema::ActOnPatternList(SmallVectorImpl<Sema::ParsedPatEltResult> &PatList,
+                       SourceLocation LLoc) {
   if (PatList.empty()) {
     Diag(LLoc, diag::err_empty_stbind_pattern);
     return StmtError();
@@ -748,7 +747,8 @@ StmtResult Sema::ActOnStructuredBindingPattern(
 
   // Deduce the type of the inspect condition.
   QualType DeducedType = deduceVarTypeFromInitializer(
-      /*VarDecl*/ DecompCond, DeclarationName(), DeductType, TSI, SourceRange(LLoc),
+      /*VarDecl*/ DecompCond, DeclarationName(), DeductType, TSI,
+      SourceRange(LLoc),
       /*IsDirectInit*/ false, MatchSource);
   if (DeducedType.isNull()) // deduceVarTypeFromInitializer already emits diags
     return StmtError();
@@ -777,6 +777,18 @@ StmtResult Sema::ActOnStructuredBindingPattern(
                     DecompCond->getBeginLoc(), DecompCond->getEndLoc());
   if (DecompDS.isInvalid())
     return StmtError();
+  return DecompDS;
+}
+
+StmtResult Sema::ActOnStructuredBindingPattern(
+    SourceLocation ColonLoc, SourceLocation LLoc, SourceLocation RLoc,
+    SmallVectorImpl<Sema::ParsedPatEltResult> &PatList, Stmt *SubStmt,
+    Expr *Guard, Stmt *DecompStmt, bool ExcludedFromTypeDeduction) {
+  auto *DS = static_cast<DeclStmt *>(DecompStmt);
+  auto *DecompCond = cast<DecompositionDecl>(DS->getSingleDecl());
+  if (getCurFunction()->InspectStack.empty())
+    return StmtError();
+  InspectExpr *Inspect = getCurFunction()->InspectStack.back().getPointer();
 
   // Now that we got all bindings populated with the proper type, for each
   // element in the pattern list try to ==/match() with the equivalent element
@@ -792,7 +804,7 @@ StmtResult Sema::ActOnStructuredBindingPattern(
     case ParsedPatEltAction::Match: {
       ExprResult M =
           ActOnMatchBinOp(NewBindings[I]->getBinding(),
-                          cast<Expr>(PatList[I].Elt), MatchSourceLoc);
+                          cast<Expr>(PatList[I].Elt), PatList[I].Loc);
       if (M.isInvalid())
         continue;
       if (!PatCond) {
@@ -817,8 +829,8 @@ StmtResult Sema::ActOnStructuredBindingPattern(
   }
 
   auto *SBP = StructuredBindingPatternStmt::Create(
-      Context, LLoc, ColonLoc, LLoc, RLoc, DecompDS.get(), SubStmt, Guard,
-      PatCond, ExcludedFromTypeDeduction);
+      Context, LLoc, ColonLoc, LLoc, RLoc, DecompStmt, SubStmt, Guard, PatCond,
+      ExcludedFromTypeDeduction);
 
   Inspect->addPattern(SBP);
   return SBP;

clang/test/AST/ast-dump-inspect-stmt.cpp

@@ -162,19 +162,28 @@ void TestInspect(int a, int b) {
   };
   insn_type insn;
   inspect(insn) {
-    [o, i] => { o++; };
+    [o, i] if (o+i < 12) => { o++; };
   };
   // CHECK: InspectExpr
   // CHECK: StructuredBindingPatternStmt
-  // CHECK: |-CompoundStmt {{.*}} <col:15, col:22>
-  // CHECK: | `-UnaryOperator {{.*}} <col:17, col:18> 'unsigned int' postfix '++'
-  // CHECK: |   `-DeclRefExpr {{.*}} <col:17> 'unsigned int' lvalue bitfield Binding {{.*}} 'o' 'unsigned int'
-  // CHECK: `-DeclStmt
+  // CHECK: |-CompoundStmt {{.*}} <col:29, col:36>
+  // CHECK: | `-UnaryOperator {{.*}} <col:31, col:32> 'unsigned int' postfix '++'
+  // CHECK: |   `-DeclRefExpr {{.*}} <col:31> 'unsigned int' lvalue bitfield Binding {{.*}} 'o' 'unsigned int'
+  // CHECK: |-DeclStmt
   // CHECK:   `-DecompositionDecl {{.*}} used 'insn_type &' cinit
   // CHECK:     |-BindingDecl {{.*}}  col:6 referenced o 'unsigned int'
   // CHECK:     | `-MemberExpr {{.*}} <col:6> 'unsigned int' lvalue bitfield .opc
-  // CHECK:     `-BindingDecl {{.*}}  <col:9> col:9 i 'unsigned int'
-  // CHECK:       `-MemberExpr {{.*}}  <col:9> 'unsigned int' lvalue bitfield .imm
+  // CHECK:     `-BindingDecl {{.*}} <col:9> col:9 referenced i 'unsigned int'
+  // CHECK:       `-MemberExpr {{.*}} <col:9> 'unsigned int' lvalue bitfield .imm
+  // CHECK: `-BinaryOperator {{.*}} <col:16, col:22> 'bool' '<'
+  // CHECK:   |-BinaryOperator {{.*}} <col:16, col:18> 'int' '+'
+  // CHECK:   | |-ImplicitCastExpr {{.*}} <col:16> 'int' <IntegralCast>
+  // CHECK:   | | `-ImplicitCastExpr {{.*}} <col:16> 'unsigned int' <LValueToRValue>
+  // CHECK:   | |   `-DeclRefExpr {{.*}} <col:16> 'unsigned int' lvalue bitfield Binding {{.*}} 'o' 'unsigned int'
+  // CHECK:   | `-ImplicitCastExpr {{.*}} <col:18> 'int' <IntegralCast>
+  // CHECK:   |   `-ImplicitCastExpr {{.*}} <col:18> 'unsigned int' <LValueToRValue>
+  // CHECK:   |     `-DeclRefExpr {{.*}} <col:18> 'unsigned int' lvalue bitfield Binding {{.*}} 'i' 'unsigned int'
+  // CHECK:   `-IntegerLiteral {{.*}} <col:22> 'int' 12
 }
 
 using size_t = decltype(sizeof(0));

clang/test/SemaCXX/inspect.cpp

@@ -199,6 +199,7 @@ void stbind0(int x) {
   int array[2] = {2,1};
   inspect (array) {
     [1,2] =>;
+    [id0, id1] if (id0+id1 < 10) =>;
   };
 
   using FourUInts = unsigned __attribute__((__vector_size__(16)));