[clang] 63814be - [modules] Merge variable template specializations.

[Richard Smith via cfe-commits]

Author: Richard Smith
Date: 2022-04-19T14:48:42-07:00
New Revision: 63814be4fa23ef9b36cf2d14388c7f6ba591d3b6

URL: https://github.com/llvm/llvm-project/commit/63814be4fa23ef9b36cf2d14388c7f6ba591d3b6
DIFF: https://github.com/llvm/llvm-project/commit/63814be4fa23ef9b36cf2d14388c7f6ba591d3b6.diff

LOG: [modules] Merge variable template specializations.

Added: 
    

Modified: 
    clang/lib/Serialization/ASTReaderDecl.cpp
    clang/test/Modules/Inputs/merge-template-specializations/a.h
    clang/test/Modules/Inputs/merge-template-specializations/b.h
    clang/test/Modules/Inputs/merge-template-specializations/c.h
    clang/test/Modules/merge-template-specializations.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 43aacdeda9987..9e0c3d558323f 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -2382,13 +2382,17 @@ ASTDeclReader::VisitVarTemplateSpecializationDeclImpl(
   if (writtenAsCanonicalDecl) {
     auto *CanonPattern = readDeclAs<VarTemplateDecl>();
     if (D->isCanonicalDecl()) { // It's kept in the folding set.
-      // FIXME: If it's already present, merge it.
+      VarTemplateSpecializationDecl *CanonSpec;
       if (auto *Partial = dyn_cast<VarTemplatePartialSpecializationDecl>(D)) {
-        CanonPattern->getCommonPtr()->PartialSpecializations
-            .GetOrInsertNode(Partial);
+        CanonSpec = CanonPattern->getCommonPtr()
+                        ->PartialSpecializations.GetOrInsertNode(Partial);
       } else {
-        CanonPattern->getCommonPtr()->Specializations.GetOrInsertNode(D);
+        CanonSpec =
+            CanonPattern->getCommonPtr()->Specializations.GetOrInsertNode(D);
       }
+      // If we already have a matching specialization, merge it.
+      if (CanonSpec != D)
+        mergeRedeclarable<VarDecl>(D, CanonSpec, Redecl);
     }
   }
 

diff  --git a/clang/test/Modules/Inputs/merge-template-specializations/a.h b/clang/test/Modules/Inputs/merge-template-specializations/a.h
index fb05647c0aa93..00426af2b1d59 100644
--- a/clang/test/Modules/Inputs/merge-template-specializations/a.h
+++ b/clang/test/Modules/Inputs/merge-template-specializations/a.h
@@ -1 +1,3 @@
 template<unsigned> class SmallString {};
+
+template<int> int var_template = 0;

diff  --git a/clang/test/Modules/Inputs/merge-template-specializations/b.h b/clang/test/Modules/Inputs/merge-template-specializations/b.h
index 96ce2bb1d8d6a..89d0e36d6c964 100644
--- a/clang/test/Modules/Inputs/merge-template-specializations/b.h
+++ b/clang/test/Modules/Inputs/merge-template-specializations/b.h
@@ -1,2 +1,4 @@
 #include "a.h"
 void f(SmallString<256>&);
+
+template<typename T> void use_var_template(decltype(T() + var_template<0>)) {}

diff  --git a/clang/test/Modules/Inputs/merge-template-specializations/c.h b/clang/test/Modules/Inputs/merge-template-specializations/c.h
index 100463a2f7f28..44fe4925d7c2d 100644
--- a/clang/test/Modules/Inputs/merge-template-specializations/c.h
+++ b/clang/test/Modules/Inputs/merge-template-specializations/c.h
@@ -1,3 +1,6 @@
 #include "a.h"
 struct X { SmallString<256> ss; };
+
+template<typename T> void use_var_template(decltype(T() + var_template<0>));
+
 #include "b.h"

diff  --git a/clang/test/Modules/merge-template-specializations.cpp b/clang/test/Modules/merge-template-specializations.cpp
index 25db93fbbb206..1f8e68a2e925a 100644
--- a/clang/test/Modules/merge-template-specializations.cpp
+++ b/clang/test/Modules/merge-template-specializations.cpp
@@ -3,3 +3,7 @@
 // expected-no-diagnostics
 #include "c.h"
 X x;
+
+void test_var_template() {
+  use_var_template<int>(0);
+}