Implement a new identifier-classification scheme where Sema

performs name lookup for an identifier and resolves it to a
type/expression/template/etc. in the same step. This scheme is
intended to improve both performance (by reducing the number of
redundant name lookups for a given identifier token) and error
recovery (by giving Sema a chance to correct type names before the
parser has decided that the identifier isn't a type name). For
example, this allows us to properly typo-correct type names at the
beginning of a statement:

t.c:6:3: error: use of undeclared identifier 'integer'; did you mean
'Integer'?
  integer *i = 0;
  ^~~~~~~
  Integer
t.c:1:13: note: 'Integer' declared here
typedef int Integer;
            ^


Previously, we wouldn't give a Fix-It because the typo correction
occurred after the parser had checked whether "integer" was a type
name (via Sema::getTypeName(), which isn't allowed to typo-correct)
and therefore decided to parse "integer * i = 0" as an expression. By
typo-correcting earlier, we typo-correct to the type name Integer and
parse this as a declaration. 

Moreover, in this context, we can also typo-correct identifiers to
keywords, e.g.,

t.c:7:3: error: use of undeclared identifier 'vid'; did you mean
'void'?
  vid *p = i;
  ^~~
  void

and recover appropriately.

Note that this is very much a work-in-progress. The new
Sema::ClassifyName is only used for expression-or-declaration
disambiguation in C at the statement level. The next steps will be to
make this work for the same disambiguation in C++ (where
functional-style casts make some trouble), then push it
further into the parser to eliminate more redundant name lookups.

Fixes <rdar://problem/7963833> for C and starts us down the path of
<rdar://problem/8172000>.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130082 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 9 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index da7619d0f4..1a8c4c9e04 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1708,11 +1708,10 @@ bool Sema::canSynthesizeProvisionalIvar(ObjCPropertyDecl *Property) {
   return true;
 }
 
-static ObjCIvarDecl *SynthesizeProvisionalIvar(Sema &SemaRef,
-                                               LookupResult &Lookup,
-                                               IdentifierInfo *II,
-                                               SourceLocation NameLoc) {
-  ObjCMethodDecl *CurMeth = SemaRef.getCurMethodDecl();
+ObjCIvarDecl *Sema::SynthesizeProvisionalIvar(LookupResult &Lookup,
+                                              IdentifierInfo *II,
+                                              SourceLocation NameLoc) {
+  ObjCMethodDecl *CurMeth = getCurMethodDecl();
   bool LookForIvars;
   if (Lookup.empty())
     LookForIvars = true;
@@ -1732,7 +1731,7 @@ static ObjCIvarDecl *SynthesizeProvisionalIvar(Sema &SemaRef,
   if (!ClassImpDecl)
     return 0;
   bool DynamicImplSeen = false;
-  ObjCPropertyDecl *property = SemaRef.LookupPropertyDecl(IDecl, II);
+  ObjCPropertyDecl *property = LookupPropertyDecl(IDecl, II);
   if (!property)
     return 0;
   if (ObjCPropertyImplDecl *PIDecl = ClassImpDecl->FindPropertyImplDecl(II)) {
@@ -1744,8 +1743,8 @@ static ObjCIvarDecl *SynthesizeProvisionalIvar(Sema &SemaRef,
       return 0;
   }
   if (!DynamicImplSeen) {
-    QualType PropType = SemaRef.Context.getCanonicalType(property->getType());
-    ObjCIvarDecl *Ivar = ObjCIvarDecl::Create(SemaRef.Context, ClassImpDecl, 
+    QualType PropType = Context.getCanonicalType(property->getType());
+    ObjCIvarDecl *Ivar = ObjCIvarDecl::Create(Context, ClassImpDecl, 
                                               NameLoc, NameLoc,
                                               II, PropType, /*Dinfo=*/0,
                                               ObjCIvarDecl::Private,
@@ -1848,7 +1847,7 @@ ExprResult Sema::ActOnIdExpression(Scope *S,
       // Synthesize ivars lazily.
       if (getLangOptions().ObjCDefaultSynthProperties &&
           getLangOptions().ObjCNonFragileABI2) {
-        if (SynthesizeProvisionalIvar(*this, R, II, NameLoc)) {
+        if (SynthesizeProvisionalIvar(R, II, NameLoc)) {
           if (const ObjCPropertyDecl *Property = 
                 canSynthesizeProvisionalIvar(II)) {
             Diag(NameLoc, diag::warn_synthesized_ivar_access) << II;