[C++] Implement "Deducing this" (P0847R7)

This patch implements P0847R7 (partially),
CWG2561 and CWG2653.

Reviewed By: aaron.ballman, #clang-language-wg

Differential Revision: https://reviews.llvm.org/D140828

1 files changed, 33 insertions, 31 deletions

diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index 72304e5..75730ea 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -769,14 +769,12 @@ bool Sema::handlerCanCatch(QualType HandlerType, QualType ExceptionType) {
 /// CheckExceptionSpecSubset - Check whether the second function type's
 /// exception specification is a subset (or equivalent) of the first function
 /// type. This is used by override and pointer assignment checks.
-bool Sema::CheckExceptionSpecSubset(const PartialDiagnostic &DiagID,
-                                    const PartialDiagnostic &NestedDiagID,
-                                    const PartialDiagnostic &NoteID,
-                                    const PartialDiagnostic &NoThrowDiagID,
-                                    const FunctionProtoType *Superset,
-                                    SourceLocation SuperLoc,
-                                    const FunctionProtoType *Subset,
-                                    SourceLocation SubLoc) {
+bool Sema::CheckExceptionSpecSubset(
+    const PartialDiagnostic &DiagID, const PartialDiagnostic &NestedDiagID,
+    const PartialDiagnostic &NoteID, const PartialDiagnostic &NoThrowDiagID,
+    const FunctionProtoType *Superset, bool SkipSupersetFirstParameter,
+    SourceLocation SuperLoc, const FunctionProtoType *Subset,
+    bool SkipSubsetFirstParameter, SourceLocation SubLoc) {
 
   // Just auto-succeed under -fno-exceptions.
   if (!getLangOpts().CXXExceptions)
@@ -816,8 +814,9 @@ bool Sema::CheckExceptionSpecSubset(const PartialDiagnostic &DiagID,
   // done.
   if ((SuperCanThrow == CT_Can && SuperEST != EST_Dynamic) ||
       SubCanThrow == CT_Cannot)
-    return CheckParamExceptionSpec(NestedDiagID, NoteID, Superset, SuperLoc,
-                                   Subset, SubLoc);
+    return CheckParamExceptionSpec(NestedDiagID, NoteID, Superset,
+                                   SkipSupersetFirstParameter, SuperLoc, Subset,
+                                   SkipSubsetFirstParameter, SubLoc);
 
   // Allow __declspec(nothrow) to be missing on redeclaration as an extension in
   // some cases.
@@ -869,8 +868,9 @@ bool Sema::CheckExceptionSpecSubset(const PartialDiagnostic &DiagID,
     }
   }
   // We've run half the gauntlet.
-  return CheckParamExceptionSpec(NestedDiagID, NoteID, Superset, SuperLoc,
-                                 Subset, SubLoc);
+  return CheckParamExceptionSpec(NestedDiagID, NoteID, Superset,
+                                 SkipSupersetFirstParameter, SuperLoc, Subset,
+                                 SkipSupersetFirstParameter, SubLoc);
 }
 
 static bool
@@ -894,12 +894,11 @@ CheckSpecForTypesEquivalent(Sema &S, const PartialDiagnostic &DiagID,
 /// assignment and override compatibility check. We do not check the parameters
 /// of parameter function pointers recursively, as no sane programmer would
 /// even be able to write such a function type.
-bool Sema::CheckParamExceptionSpec(const PartialDiagnostic &DiagID,
-                                   const PartialDiagnostic &NoteID,
-                                   const FunctionProtoType *Target,
-                                   SourceLocation TargetLoc,
-                                   const FunctionProtoType *Source,
-                                   SourceLocation SourceLoc) {
+bool Sema::CheckParamExceptionSpec(
+    const PartialDiagnostic &DiagID, const PartialDiagnostic &NoteID,
+    const FunctionProtoType *Target, bool SkipTargetFirstParameter,
+    SourceLocation TargetLoc, const FunctionProtoType *Source,
+    bool SkipSourceFirstParameter, SourceLocation SourceLoc) {
   auto RetDiag = DiagID;
   RetDiag << 0;
   if (CheckSpecForTypesEquivalent(
@@ -910,14 +909,16 @@ bool Sema::CheckParamExceptionSpec(const PartialDiagnostic &DiagID,
 
   // We shouldn't even be testing this unless the arguments are otherwise
   // compatible.
-  assert(Target->getNumParams() == Source->getNumParams() &&
+  assert((Target->getNumParams() - (unsigned)SkipTargetFirstParameter) ==
+             (Source->getNumParams() - (unsigned)SkipSourceFirstParameter) &&
          "Functions have different argument counts.");
   for (unsigned i = 0, E = Target->getNumParams(); i != E; ++i) {
     auto ParamDiag = DiagID;
     ParamDiag << 1;
     if (CheckSpecForTypesEquivalent(
             *this, ParamDiag, PDiag(),
-            Target->getParamType(i), TargetLoc, Source->getParamType(i),
+            Target->getParamType(i + (SkipTargetFirstParameter ? 1 : 0)),
+            TargetLoc, Source->getParamType(SkipSourceFirstParameter ? 1 : 0),
             SourceLoc))
       return true;
   }
@@ -958,9 +959,10 @@ bool Sema::CheckExceptionSpecCompatibility(Expr *From, QualType ToType) {
   //     void (*q)(void (*) throw(int)) = p;
   //   }
   // ... because it might be instantiated with T=int.
-  return CheckExceptionSpecSubset(
-             PDiag(DiagID), PDiag(NestedDiagID), PDiag(), PDiag(), ToFunc,
-             From->getSourceRange().getBegin(), FromFunc, SourceLocation()) &&
+  return CheckExceptionSpecSubset(PDiag(DiagID), PDiag(NestedDiagID), PDiag(),
+                                  PDiag(), ToFunc, 0,
+                                  From->getSourceRange().getBegin(), FromFunc,
+                                  0, SourceLocation()) &&
          !getLangOpts().CPlusPlus17;
 }
 
@@ -989,14 +991,14 @@ bool Sema::CheckOverridingFunctionExceptionSpec(const CXXMethodDecl *New,
   unsigned DiagID = diag::err_override_exception_spec;
   if (getLangOpts().MSVCCompat)
     DiagID = diag::ext_override_exception_spec;
-  return CheckExceptionSpecSubset(PDiag(DiagID),
-                                  PDiag(diag::err_deep_exception_specs_differ),
-                                  PDiag(diag::note_overridden_virtual_function),
-                                  PDiag(diag::ext_override_exception_spec),
-                                  Old->getType()->castAs<FunctionProtoType>(),
-                                  Old->getLocation(),
-                                  New->getType()->castAs<FunctionProtoType>(),
-                                  New->getLocation());
+  return CheckExceptionSpecSubset(
+      PDiag(DiagID), PDiag(diag::err_deep_exception_specs_differ),
+      PDiag(diag::note_overridden_virtual_function),
+      PDiag(diag::ext_override_exception_spec),
+      Old->getType()->castAs<FunctionProtoType>(),
+      Old->hasCXXExplicitFunctionObjectParameter(), Old->getLocation(),
+      New->getType()->castAs<FunctionProtoType>(),
+      New->hasCXXExplicitFunctionObjectParameter(), New->getLocation());
 }
 
 static CanThrowResult canSubStmtsThrow(Sema &Self, const Stmt *S) {