[clang] [clang][ExtractAPI] improve template argument name deduction (PR #77716)

Erick Velez via cfe-commits cfe-commits at lists.llvm.org
Wed Jan 10 18:52:46 PST 2024


https://github.com/evelez7 created https://github.com/llvm/llvm-project/pull/77716

The names of template arguments in partial specializations or parameters used as types might be mangled according to index and depth. Instead of looping through parameter lists to find matches like we do now, they can be deduced via their QualTypes or as written from the AST.

>From ac995ade6d9e4e0ebf4e897594ccfa5c4f5e4b60 Mon Sep 17 00:00:00 2001
From: Erick Velez <erickvelez7 at gmail.com>
Date: Wed, 10 Jan 2024 18:28:19 -0800
Subject: [PATCH] [clang][ExtractAPI] improve template argument name deduction

The names of template arguments in partial specializations or parameters used as
types might be mangled according to index and depth. Instead of looping
through parameter lists to find matches like we do now, they can be
deduced via their QualTypes or as written from the AST.
---
 .../clang/ExtractAPI/DeclarationFragments.h   | 22 +++----
 clang/lib/ExtractAPI/DeclarationFragments.cpp | 58 +++++--------------
 .../class_template_partial_spec.cpp           |  3 +-
 .../global_var_template_partial_spec.cpp      |  3 +-
 4 files changed, 25 insertions(+), 61 deletions(-)

diff --git a/clang/include/clang/ExtractAPI/DeclarationFragments.h b/clang/include/clang/ExtractAPI/DeclarationFragments.h
index d719196b9a43ec..5af4a01fa6bb9c 100644
--- a/clang/include/clang/ExtractAPI/DeclarationFragments.h
+++ b/clang/include/clang/ExtractAPI/DeclarationFragments.h
@@ -27,8 +27,6 @@
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Lex/MacroInfo.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringRef.h"
 #include <vector>
 
 namespace clang {
@@ -67,6 +65,9 @@ class DeclarationFragments {
     /// parameters.
     GenericParameter,
 
+    /// Argument for partial template specialization.
+    GenericArgument,
+
     /// External parameters in Objective-C methods.
     /// For example, \c forKey in
     /// \code{.m}
@@ -314,13 +315,9 @@ class DeclarationFragmentsBuilder {
   static DeclarationFragments
       getFragmentsForTemplateParameters(ArrayRef<NamedDecl *>);
 
-  static std::string
-  getNameForTemplateArgument(const ArrayRef<NamedDecl *>, std::string);
-
-  static DeclarationFragments
-  getFragmentsForTemplateArguments(const ArrayRef<TemplateArgument>,
-                                   ASTContext &,
-                                   const std::optional<ArrayRef<NamedDecl *>>);
+  static DeclarationFragments getFragmentsForTemplateArguments(
+      const ArrayRef<TemplateArgument>, ASTContext &,
+      const std::optional<ArrayRef<TemplateArgumentLoc>>);
 
   static DeclarationFragments getFragmentsForConcept(const ConceptDecl *);
 
@@ -430,12 +427,7 @@ DeclarationFragmentsBuilder::getFunctionSignature(const FunctionT *Function) {
       dyn_cast<FunctionDecl>(Function)->getDescribedFunctionTemplate() &&
       ReturnType.begin()->Spelling.substr(0, 14).compare("type-parameter") ==
           0) {
-    std::string ProperArgName =
-        getNameForTemplateArgument(dyn_cast<FunctionDecl>(Function)
-                                       ->getDescribedFunctionTemplate()
-                                       ->getTemplateParameters()
-                                       ->asArray(),
-                                   ReturnType.begin()->Spelling);
+    std::string ProperArgName = Function->getReturnType().getAsString();
     ReturnType.begin()->Spelling.swap(ProperArgName);
   }
   ReturnType.append(std::move(After));
diff --git a/clang/lib/ExtractAPI/DeclarationFragments.cpp b/clang/lib/ExtractAPI/DeclarationFragments.cpp
index eb6eea0aaf5465..2c82aeab6083ba 100644
--- a/clang/lib/ExtractAPI/DeclarationFragments.cpp
+++ b/clang/lib/ExtractAPI/DeclarationFragments.cpp
@@ -14,14 +14,11 @@
 #include "clang/ExtractAPI/DeclarationFragments.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclCXX.h"
-#include "clang/AST/QualTypeNames.h"
 #include "clang/AST/Type.h"
 #include "clang/AST/TypeLoc.h"
-#include "clang/Basic/OperatorKinds.h"
 #include "clang/ExtractAPI/TypedefUnderlyingTypeResolver.h"
 #include "clang/Index/USRGeneration.h"
 #include "llvm/ADT/StringSwitch.h"
-#include <typeinfo>
 
 using namespace clang::extractapi;
 using namespace llvm;
@@ -102,6 +99,8 @@ StringRef DeclarationFragments::getFragmentKindString(
     return "internalParam";
   case DeclarationFragments::FragmentKind::Text:
     return "text";
+  case DeclarationFragments::FragmentKind::GenericArgument:
+    return "genericArgument";
   }
 
   llvm_unreachable("Unhandled FragmentKind");
@@ -122,6 +121,8 @@ DeclarationFragments::parseFragmentKindFromString(StringRef S) {
       .Case("internalParam", DeclarationFragments::FragmentKind::InternalParam)
       .Case("externalParam", DeclarationFragments::FragmentKind::ExternalParam)
       .Case("text", DeclarationFragments::FragmentKind::Text)
+      .Case("genericArgument",
+            DeclarationFragments::FragmentKind::GenericArgument)
       .Default(DeclarationFragments::FragmentKind::None);
 }
 
@@ -535,9 +536,7 @@ DeclarationFragmentsBuilder::getFragmentsForVarTemplate(const VarDecl *Var) {
       getFragmentsForType(T, Var->getASTContext(), After);
   if (ArgumentFragment.begin()->Spelling.substr(0, 14).compare(
           "type-parameter") == 0) {
-    std::string ProperArgName = getNameForTemplateArgument(
-        Var->getDescribedVarTemplate()->getTemplateParameters()->asArray(),
-        ArgumentFragment.begin()->Spelling);
+    std::string ProperArgName = T.getAsString();
     ArgumentFragment.begin()->Spelling.swap(ProperArgName);
   }
   Fragments.append(std::move(ArgumentFragment))
@@ -570,12 +569,7 @@ DeclarationFragmentsBuilder::getFragmentsForParam(const ParmVarDecl *Param) {
 
   if (TypeFragments.begin()->Spelling.substr(0, 14).compare("type-parameter") ==
       0) {
-    std::string ProperArgName = getNameForTemplateArgument(
-        dyn_cast<FunctionDecl>(Param->getDeclContext())
-            ->getDescribedFunctionTemplate()
-            ->getTemplateParameters()
-            ->asArray(),
-        TypeFragments.begin()->Spelling);
+    std::string ProperArgName = Param->getOriginalType().getAsString();
     TypeFragments.begin()->Spelling.swap(ProperArgName);
   }
 
@@ -668,11 +662,7 @@ DeclarationFragmentsBuilder::getFragmentsForFunction(const FunctionDecl *Func) {
       getFragmentsForType(Func->getReturnType(), Func->getASTContext(), After);
   if (ReturnValueFragment.begin()->Spelling.substr(0, 14).compare(
           "type-parameter") == 0) {
-    std::string ProperArgName =
-        getNameForTemplateArgument(Func->getDescribedFunctionTemplate()
-                                       ->getTemplateParameters()
-                                       ->asArray(),
-                                   ReturnValueFragment.begin()->Spelling);
+    std::string ProperArgName = Func->getReturnType().getAsString();
     ReturnValueFragment.begin()->Spelling.swap(ProperArgName);
   }
 
@@ -958,25 +948,6 @@ DeclarationFragmentsBuilder::getFragmentsForTemplateParameters(
   return Fragments;
 }
 
-// Find the name of a template argument from the template's parameters.
-std::string DeclarationFragmentsBuilder::getNameForTemplateArgument(
-    const ArrayRef<NamedDecl *> TemplateParameters, std::string TypeParameter) {
-  // The arg is a generic parameter from a partial spec, e.g.
-  // T in template<typename T> Foo<T, int>.
-  //
-  // Those names appear as "type-parameter-<index>-<depth>", so we must find its
-  // name from the template's parameter list.
-  for (unsigned i = 0; i < TemplateParameters.size(); ++i) {
-    const auto *Parameter =
-        dyn_cast<TemplateTypeParmDecl>(TemplateParameters[i]);
-    if (TypeParameter.compare("type-parameter-" +
-                              std::to_string(Parameter->getDepth()) + "-" +
-                              std::to_string(Parameter->getIndex())) == 0)
-      return std::string(TemplateParameters[i]->getName());
-  }
-  llvm_unreachable("Could not find the name of a template argument.");
-}
-
 // Get fragments for template arguments, e.g. int in template<typename T>
 // Foo<int>;
 //
@@ -986,7 +957,7 @@ std::string DeclarationFragmentsBuilder::getNameForTemplateArgument(
 DeclarationFragments
 DeclarationFragmentsBuilder::getFragmentsForTemplateArguments(
     const ArrayRef<TemplateArgument> TemplateArguments, ASTContext &Context,
-    const std::optional<ArrayRef<NamedDecl *>> TemplateParameters) {
+    const std::optional<ArrayRef<TemplateArgumentLoc>> TemplateArgumentLocs) {
   DeclarationFragments Fragments;
   for (unsigned i = 0, end = TemplateArguments.size(); i != end; ++i) {
     if (i)
@@ -1000,9 +971,12 @@ DeclarationFragmentsBuilder::getFragmentsForTemplateArguments(
 
     if (ArgumentFragment.begin()->Spelling.substr(0, 14).compare(
             "type-parameter") == 0) {
-      std::string ProperArgName = getNameForTemplateArgument(
-          TemplateParameters.value(), ArgumentFragment.begin()->Spelling);
-      ArgumentFragment.begin()->Spelling.swap(ProperArgName);
+      std::string ProperArgName = TemplateArgumentLocs.value()[i]
+                                      .getTypeSourceInfo()
+                                      ->getType()
+                                      .getAsString();
+      ArgumentFragment = DeclarationFragments().append(
+          ProperArgName, DeclarationFragments::FragmentKind::GenericArgument);
     }
     Fragments.append(std::move(ArgumentFragment));
 
@@ -1086,7 +1060,7 @@ DeclarationFragmentsBuilder::getFragmentsForClassTemplatePartialSpecialization(
       .append("<", DeclarationFragments::FragmentKind::Text)
       .append(getFragmentsForTemplateArguments(
           Decl->getTemplateArgs().asArray(), Decl->getASTContext(),
-          Decl->getTemplateParameters()->asArray()))
+          Decl->getTemplateArgsAsWritten()->arguments()))
       .append(">", DeclarationFragments::FragmentKind::Text)
       .append(";", DeclarationFragments::FragmentKind::Text);
 }
@@ -1127,7 +1101,7 @@ DeclarationFragmentsBuilder::getFragmentsForVarTemplatePartialSpecialization(
       .append("<", DeclarationFragments::FragmentKind::Text)
       .append(getFragmentsForTemplateArguments(
           Decl->getTemplateArgs().asArray(), Decl->getASTContext(),
-          Decl->getTemplateParameters()->asArray()))
+          Decl->getTemplateArgsAsWritten()->arguments()))
       .append(">", DeclarationFragments::FragmentKind::Text)
       .append(";", DeclarationFragments::FragmentKind::Text);
 }
diff --git a/clang/test/ExtractAPI/class_template_partial_spec.cpp b/clang/test/ExtractAPI/class_template_partial_spec.cpp
index eba069319ce450..fc21d61297e4b9 100644
--- a/clang/test/ExtractAPI/class_template_partial_spec.cpp
+++ b/clang/test/ExtractAPI/class_template_partial_spec.cpp
@@ -196,8 +196,7 @@ template<typename Z> class Foo<Z, int> {};
           "spelling": "<"
         },
         {
-          "kind": "typeIdentifier",
-          "preciseIdentifier": "c:t0.0",
+          "kind": "genericArgument",
           "spelling": "Z"
         },
         {
diff --git a/clang/test/ExtractAPI/global_var_template_partial_spec.cpp b/clang/test/ExtractAPI/global_var_template_partial_spec.cpp
index e98076cdb1d016..cca571ff1999fe 100644
--- a/clang/test/ExtractAPI/global_var_template_partial_spec.cpp
+++ b/clang/test/ExtractAPI/global_var_template_partial_spec.cpp
@@ -206,8 +206,7 @@ template<typename Z> int Foo<int, Z> = 0;
           "spelling": ", "
         },
         {
-          "kind": "typeIdentifier",
-          "preciseIdentifier": "c:t0.0",
+          "kind": "genericArgument",
           "spelling": "Z"
         },
         {



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