FIXME fix: improving diagnostics for template arguments deduction of class templates and explicit specializations

    This patch essentially removes all the FIXMEs following calls to DeduceTemplateArguments() that want to keep track of deduction failure info.

llvm-svn: 186730

1 files changed, 29 insertions, 22 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 6f1ab19f10e..7939c48c64b 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -5925,13 +5925,13 @@ Sema::CheckDependentFunctionTemplateSpecialization(FunctionDecl *FD,
 ///
 /// \param Previous the set of declarations that may be specialized by
 /// this function specialization.
-bool
-Sema::CheckFunctionTemplateSpecialization(FunctionDecl *FD,
-                                 TemplateArgumentListInfo *ExplicitTemplateArgs,
-                                          LookupResult &Previous) {
+bool Sema::CheckFunctionTemplateSpecialization(
+    FunctionDecl *FD, TemplateArgumentListInfo *ExplicitTemplateArgs,
+    LookupResult &Previous) {
   // The set of function template specializations that could match this
   // explicit function template specialization.
   UnresolvedSet<8> Candidates;
+  TemplateSpecCandidateSet FailedCandidates(FD->getLocation());
 
   DeclContext *FDLookupContext = FD->getDeclContext()->getRedeclContext();
   for (LookupResult::iterator I = Previous.begin(), E = Previous.end();
@@ -5969,13 +5969,16 @@ Sema::CheckFunctionTemplateSpecialization(FunctionDecl *FD,
       // Perform template argument deduction to determine whether we may be
       // specializing this template.
       // FIXME: It is somewhat wasteful to build
-      TemplateDeductionInfo Info(FD->getLocation());
+      TemplateDeductionInfo Info(FailedCandidates.getLocation());
       FunctionDecl *Specialization = 0;
       if (TemplateDeductionResult TDK
             = DeduceTemplateArguments(FunTmpl, ExplicitTemplateArgs, FT,
                                       Specialization, Info)) {
-        // FIXME: Template argument deduction failed; record why it failed, so
+        // Template argument deduction failed; record why it failed, so
         // that we can provide nifty diagnostics.
+        FailedCandidates.addCandidate()
+            .set(FunTmpl->getTemplatedDecl(),
+                 MakeDeductionFailureInfo(Context, TDK, Info));
         (void)TDK;
         continue;
       }
@@ -5986,14 +5989,14 @@ Sema::CheckFunctionTemplateSpecialization(FunctionDecl *FD,
   }
 
   // Find the most specialized function template.
-  UnresolvedSetIterator Result
-    = getMostSpecialized(Candidates.begin(), Candidates.end(),
-                         TPOC_Other, 0, FD->getLocation(),
-                  PDiag(diag::err_function_template_spec_no_match)
-                    << FD->getDeclName(),
-                  PDiag(diag::err_function_template_spec_ambiguous)
-                    << FD->getDeclName() << (ExplicitTemplateArgs != 0),
-                  PDiag(diag::note_function_template_spec_matched));
+  UnresolvedSetIterator Result = getMostSpecialized(
+      Candidates.begin(), Candidates.end(), FailedCandidates, TPOC_Other, 0,
+      FD->getLocation(),
+      PDiag(diag::err_function_template_spec_no_match) << FD->getDeclName(),
+      PDiag(diag::err_function_template_spec_ambiguous)
+          << FD->getDeclName() << (ExplicitTemplateArgs != 0),
+      PDiag(diag::note_function_template_spec_matched));
+
   if (Result == Candidates.end())
     return true;
 
@@ -6812,6 +6815,7 @@ DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
   //  instantiated from the member definition associated with its class
   //  template.
   UnresolvedSet<8> Matches;
+  TemplateSpecCandidateSet FailedCandidates(D.getIdentifierLoc());
   for (LookupResult::iterator P = Previous.begin(), PEnd = Previous.end();
        P != PEnd; ++P) {
     NamedDecl *Prev = *P;
@@ -6831,13 +6835,16 @@ DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
     if (!FunTmpl)
       continue;
 
-    TemplateDeductionInfo Info(D.getIdentifierLoc());
+    TemplateDeductionInfo Info(FailedCandidates.getLocation());
     FunctionDecl *Specialization = 0;
     if (TemplateDeductionResult TDK
           = DeduceTemplateArguments(FunTmpl,
                                (HasExplicitTemplateArgs ? &TemplateArgs : 0),
                                     R, Specialization, Info)) {
-      // FIXME: Keep track of almost-matches?
+      // Keep track of almost-matches.
+      FailedCandidates.addCandidate()
+          .set(FunTmpl->getTemplatedDecl(),
+               MakeDeductionFailureInfo(Context, TDK, Info));
       (void)TDK;
       continue;
     }
@@ -6846,12 +6853,12 @@ DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
   }
 
   // Find the most specialized function template specialization.
-  UnresolvedSetIterator Result
-    = getMostSpecialized(Matches.begin(), Matches.end(), TPOC_Other, 0,
-                         D.getIdentifierLoc(),
-                     PDiag(diag::err_explicit_instantiation_not_known) << Name,
-                     PDiag(diag::err_explicit_instantiation_ambiguous) << Name,
-                         PDiag(diag::note_explicit_instantiation_candidate));
+  UnresolvedSetIterator Result = getMostSpecialized(
+      Matches.begin(), Matches.end(), FailedCandidates, TPOC_Other, 0,
+      D.getIdentifierLoc(),
+      PDiag(diag::err_explicit_instantiation_not_known) << Name,
+      PDiag(diag::err_explicit_instantiation_ambiguous) << Name,
+      PDiag(diag::note_explicit_instantiation_candidate));
 
   if (Result == Matches.end())
     return true;