[clang] 802d8d9 - [Clang] Don't ditch typo-corrected lookup result (#139374)

[via cfe-commits]

Author: Younan Zhang
Date: 2025-05-10T20:44:45+08:00
New Revision: 802d8d90776b476ca8f257ab2e4fa2db185c6b69

URL: https://github.com/llvm/llvm-project/commit/802d8d90776b476ca8f257ab2e4fa2db185c6b69
DIFF: https://github.com/llvm/llvm-project/commit/802d8d90776b476ca8f257ab2e4fa2db185c6b69.diff

LOG: [Clang] Don't ditch typo-corrected lookup result (#139374)

For a member function call like 'foo.bar<int>()', there are two
typo-correction points after parsing the dot. The first occurs in
ParseOptionalCXXScopeSpecifier, which tries to annotate the template
name following any scope specifiers.

If the template name bar is not found within 'foo', the parser was
previously instructed to drop any function templates found outside of
the scope. This was intended to prevent ambiguity in expressions like
'foo->bar < 7', as explained in commit 50a3cddd. However, it's
unnecessary to discard typo-corrected results that were strictly
resolved within the scope 'foo'.

We won't perform a second typo-correction in ParseUnqualifiedId after
the name being annotated.

Fixes https://github.com/llvm/llvm-project/issues/139226

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Sema/SemaTemplate.cpp
    clang/test/CXX/basic/basic.lookup/basic.lookup.classref/p1.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 1d0896f585fb4..e362ec595a3bb 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -517,7 +517,10 @@ Improvements to Clang's diagnostics
 
 - Improved the ``-Wtautological-overlap-compare`` diagnostics to warn about overlapping and non-overlapping ranges involving character literals and floating-point literals. 
   The warning message for non-overlapping cases has also been improved (#GH13473).
-  
+
+- Fixed a duplicate diagnostic when performing typo correction on function template
+  calls with explicit template arguments. (#GH139226)
+
 Improvements to Clang's time-trace
 ----------------------------------
 

diff  --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 2ba69c87d95e3..7940340064eda 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -523,6 +523,9 @@ bool Sema::LookupTemplateName(LookupResult &Found, Scope *S, CXXScopeSpec &SS,
       if (Found.isAmbiguous()) {
         Found.clear();
       } else if (!Found.empty()) {
+        // Do not erase the typo-corrected result to avoid duplicated
+        // diagnostics.
+        AllowFunctionTemplatesInLookup = true;
         Found.setLookupName(Corrected.getCorrection());
         if (LookupCtx) {
           std::string CorrectedStr(Corrected.getAsString(getLangOpts()));

diff  --git a/clang/test/CXX/basic/basic.lookup/basic.lookup.classref/p1.cpp b/clang/test/CXX/basic/basic.lookup/basic.lookup.classref/p1.cpp
index e3599db18350b..3633ef1c293e2 100644
--- a/clang/test/CXX/basic/basic.lookup/basic.lookup.classref/p1.cpp
+++ b/clang/test/CXX/basic/basic.lookup/basic.lookup.classref/p1.cpp
@@ -98,3 +98,16 @@ namespace PR11856 {
     }
   }
 }
+
+namespace GH139226 {
+
+struct Foo {
+  template <class T> void LookupWithID(); // expected-note {{declared here}}
+};
+
+void test(Foo &f) {
+  f.LookupWithId<int>();
+  // expected-error at -1 {{did you mean 'LookupWithID'}}
+}
+
+}