[clang] [libclang] Allow using PrintingPolicy with types (PR #122386)

[Eli Friedman via cfe-commits]

https://github.com/efriedma-quic created https://github.com/llvm/llvm-project/pull/122386

This allows controlling pretty-printing of types the same way it works with cursors.

>From a96fbe38f697f77c12c712f5573c2158072a8d2f Mon Sep 17 00:00:00 2001
From: Eli Friedman <efriedma at quicinc.com>
Date: Tue, 17 Dec 2024 17:46:09 -0800
Subject: [PATCH] [libclang] Allow using PrintingPolicy with types

This allows controlling pretty-printing of types the same way it works
with cursors.
---
 clang/bindings/python/clang/cindex.py         |  6 ++++++
 .../bindings/python/tests/cindex/test_type.py | 19 ++++++++++++++++++-
 clang/docs/ReleaseNotes.rst                   |  2 ++
 clang/include/clang-c/Index.h                 |  7 +++++++
 clang/tools/libclang/CXType.cpp               | 14 ++++++++++++++
 clang/tools/libclang/libclang.map             |  1 +
 6 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/clang/bindings/python/clang/cindex.py b/clang/bindings/python/clang/cindex.py
index 7caf0bbfd722af..e01285e27fcdf9 100644
--- a/clang/bindings/python/clang/cindex.py
+++ b/clang/bindings/python/clang/cindex.py
@@ -2701,6 +2701,11 @@ def spelling(self):
         """Retrieve the spelling of this Type."""
         return _CXString.from_result(conf.lib.clang_getTypeSpelling(self))
 
+    def pretty_printed(self, policy):
+        """Pretty-prints this Type with the given PrintingPolicy"""
+        return _CXString.from_result(conf.lib.clang_getTypePrettyPrinted(self, policy))
+
+
     def __eq__(self, other):
         if type(other) != type(self):
             return False
@@ -3955,6 +3960,7 @@ def set_property(self, property, value):
     ("clang_getTypedefDeclUnderlyingType", [Cursor], Type),
     ("clang_getTypedefName", [Type], _CXString),
     ("clang_getTypeKindSpelling", [c_uint], _CXString),
+    ("clang_getTypePrettyPrinted", [Type, PrintingPolicy], _CXString),
     ("clang_getTypeSpelling", [Type], _CXString),
     ("clang_hashCursor", [Cursor], c_uint),
     ("clang_isAttribute", [CursorKind], bool),
diff --git a/clang/bindings/python/tests/cindex/test_type.py b/clang/bindings/python/tests/cindex/test_type.py
index e1d8c2aad1c3a4..da27ba5bda3ee0 100644
--- a/clang/bindings/python/tests/cindex/test_type.py
+++ b/clang/bindings/python/tests/cindex/test_type.py
@@ -1,6 +1,14 @@
 import os
 
-from clang.cindex import Config, CursorKind, RefQualifierKind, TranslationUnit, TypeKind
+from clang.cindex import (
+    Config,
+    CursorKind,
+    PrintingPolicy,
+    PrintingPolicyProperty,
+    RefQualifierKind,
+    TranslationUnit,
+    TypeKind
+)
 
 if "CLANG_LIBRARY_PATH" in os.environ:
     Config.set_library_path(os.environ["CLANG_LIBRARY_PATH"])
@@ -517,3 +525,12 @@ class Template {
         # Variable without a template argument.
         cursor = get_cursor(tu, "bar")
         self.assertEqual(cursor.get_num_template_arguments(), -1)
+
+    def test_pretty(self):
+        tu = get_tu("struct X {}; X x;", lang="cpp")
+        f = get_cursor(tu, "x")
+
+        pp = PrintingPolicy.create(f)
+        self.assertEqual(f.type.get_canonical().pretty_printed(pp), "X")
+        pp.set_property(PrintingPolicyProperty.SuppressTagKeyword, False)
+        self.assertEqual(f.type.get_canonical().pretty_printed(pp), "struct X")
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 07a1a4195427d8..d0479a94bd67ce 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -1158,6 +1158,8 @@ libclang
 --------
 - Add ``clang_isBeforeInTranslationUnit``. Given two source locations, it determines
   whether the first one comes strictly before the second in the source code.
+- Add ``clang_getTypePrettyPrinted``.  It allows controlling the PrintingPolicy used
+  to pretty-print a type.
 
 Static Analyzer
 ---------------
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index 63d266dc60ec73..e1f3759bb53e85 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -4182,6 +4182,13 @@ CINDEX_LINKAGE void clang_PrintingPolicy_dispose(CXPrintingPolicy Policy);
 CINDEX_LINKAGE CXString clang_getCursorPrettyPrinted(CXCursor Cursor,
                                                      CXPrintingPolicy Policy);
 
+/**
+ * Pretty-print the underlying type using a custom printing policy.
+ *
+ * If the type is invalid, an empty string is returned.
+ */
+CINDEX_LINKAGE CXString clang_getTypePrettyPrinted(CXType CT, CXPrintingPolicy cxPolicy);
+
 /**
  * Retrieve the display name for the entity referenced by this cursor.
  *
diff --git a/clang/tools/libclang/CXType.cpp b/clang/tools/libclang/CXType.cpp
index b4df12405cf356..f97023c429bfae 100644
--- a/clang/tools/libclang/CXType.cpp
+++ b/clang/tools/libclang/CXType.cpp
@@ -313,6 +313,20 @@ CXString clang_getTypeSpelling(CXType CT) {
   return cxstring::createDup(OS.str());
 }
 
+CXString clang_getTypePrettyPrinted(CXType CT, CXPrintingPolicy cxPolicy) {
+  QualType T = GetQualType(CT);
+  if (T.isNull())
+    return cxstring::createEmpty();
+
+  SmallString<64> Str;
+  llvm::raw_svector_ostream OS(Str);
+  PrintingPolicy *UserPolicy = static_cast<PrintingPolicy *>(cxPolicy);
+
+  T.print(OS, *UserPolicy);
+
+  return cxstring::createDup(OS.str());
+}
+
 CXType clang_getTypedefDeclUnderlyingType(CXCursor C) {
   using namespace cxcursor;
   CXTranslationUnit TU = cxcursor::getCursorTU(C);
diff --git a/clang/tools/libclang/libclang.map b/clang/tools/libclang/libclang.map
index 25d8ba57d32514..c5f0be746ffe12 100644
--- a/clang/tools/libclang/libclang.map
+++ b/clang/tools/libclang/libclang.map
@@ -437,6 +437,7 @@ LLVM_19 {
 LLVM_20 {
   global:
     clang_isBeforeInTranslationUnit;
+    clang_getTypePrettyPrinted;
 };
 
 # Example of how to add a new symbol version entry.  If you do add a new symbol