[clang] [Clang][Sema] Process warnings conditionally (PR #120591)

[Dmitry Chestnykh via cfe-commits]

https://github.com/chestnykh updated https://github.com/llvm/llvm-project/pull/120591

>From 5b61245bbdc9d1874684f29bba880f6b5a4cfe82 Mon Sep 17 00:00:00 2001
From: Dmitry Chestnykh <dm.chestnykh at gmail.com>
Date: Thu, 19 Dec 2024 18:35:35 +0300
Subject: [PATCH 1/2] [Clang][Sema] Process warnings conditionally

There are a few functions that emit warnings
related to positional arguments in format strings.
These functions use `getLocationOfByte()` which has O(n)
complexity and may lead to silent hang of compilation in some cases.
But such warnings is not widely used and actually don't emit
if user didn't pass the appropriate `-W...` flag, so
if the flag is not passed dont make the call
to `EmitFormatDiagnostic` for such diags.

Fix #120462
---
 clang/lib/Sema/SemaChecking.cpp | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index be5d3694aec152..a745250988feeb 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -6612,27 +6612,33 @@ void CheckFormatHandler::HandleNonStandardConversionSpecifier(
 
 void CheckFormatHandler::HandlePosition(const char *startPos,
                                         unsigned posLen) {
-  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
-                               getLocationOfByte(startPos),
-                               /*IsStringLocation*/true,
-                               getSpecifierRange(startPos, posLen));
+  if (!S.getDiagnostics().isIgnored(diag::warn_format_non_standard_positional_arg, SourceLocation())) {
+    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
+                                getLocationOfByte(startPos),
+                                /*IsStringLocation*/true,
+                                getSpecifierRange(startPos, posLen));
+  }
 }
 
 void CheckFormatHandler::HandleInvalidPosition(
     const char *startSpecifier, unsigned specifierLen,
     analyze_format_string::PositionContext p) {
-  EmitFormatDiagnostic(
-      S.PDiag(diag::warn_format_invalid_positional_specifier) << (unsigned)p,
-      getLocationOfByte(startSpecifier), /*IsStringLocation*/ true,
-      getSpecifierRange(startSpecifier, specifierLen));
+  if (!S.getDiagnostics().isIgnored(diag::warn_format_invalid_positional_specifier, SourceLocation())) {
+    EmitFormatDiagnostic(
+        S.PDiag(diag::warn_format_invalid_positional_specifier) << (unsigned)p,
+        getLocationOfByte(startSpecifier), /*IsStringLocation*/ true,
+        getSpecifierRange(startSpecifier, specifierLen));
+  }
 }
 
 void CheckFormatHandler::HandleZeroPosition(const char *startPos,
                                             unsigned posLen) {
-  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
-                               getLocationOfByte(startPos),
-                               /*IsStringLocation*/true,
-                               getSpecifierRange(startPos, posLen));
+  if (!S.getDiagnostics().isIgnored(diag::warn_format_zero_positional_specifier, SourceLocation())) {
+    EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
+                                getLocationOfByte(startPos),
+                                /*IsStringLocation*/true,
+                                getSpecifierRange(startPos, posLen));
+  }
 }
 
 void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {

>From 7f93928a842888ab848a97bd5fbd981523c9c4d9 Mon Sep 17 00:00:00 2001
From: Dmitry Chestnykh <dm.chestnykh at gmail.com>
Date: Thu, 19 Dec 2024 18:50:04 +0300
Subject: [PATCH 2/2] [clang][Sema] Fix code style

---
 clang/lib/Sema/SemaChecking.cpp | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index a745250988feeb..b0076c2686a35b 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -6612,18 +6612,20 @@ void CheckFormatHandler::HandleNonStandardConversionSpecifier(
 
 void CheckFormatHandler::HandlePosition(const char *startPos,
                                         unsigned posLen) {
-  if (!S.getDiagnostics().isIgnored(diag::warn_format_non_standard_positional_arg, SourceLocation())) {
+  if (!S.getDiagnostics().isIgnored(
+          diag::warn_format_non_standard_positional_arg, SourceLocation())) {
     EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
-                                getLocationOfByte(startPos),
-                                /*IsStringLocation*/true,
-                                getSpecifierRange(startPos, posLen));
+                         getLocationOfByte(startPos),
+                         /*IsStringLocation*/ true,
+                         getSpecifierRange(startPos, posLen));
   }
 }
 
 void CheckFormatHandler::HandleInvalidPosition(
     const char *startSpecifier, unsigned specifierLen,
     analyze_format_string::PositionContext p) {
-  if (!S.getDiagnostics().isIgnored(diag::warn_format_invalid_positional_specifier, SourceLocation())) {
+  if (!S.getDiagnostics().isIgnored(
+          diag::warn_format_invalid_positional_specifier, SourceLocation())) {
     EmitFormatDiagnostic(
         S.PDiag(diag::warn_format_invalid_positional_specifier) << (unsigned)p,
         getLocationOfByte(startSpecifier), /*IsStringLocation*/ true,
@@ -6633,11 +6635,12 @@ void CheckFormatHandler::HandleInvalidPosition(
 
 void CheckFormatHandler::HandleZeroPosition(const char *startPos,
                                             unsigned posLen) {
-  if (!S.getDiagnostics().isIgnored(diag::warn_format_zero_positional_specifier, SourceLocation())) {
+  if (!S.getDiagnostics().isIgnored(diag::warn_format_zero_positional_specifier,
+                                    SourceLocation())) {
     EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
-                                getLocationOfByte(startPos),
-                                /*IsStringLocation*/true,
-                                getSpecifierRange(startPos, posLen));
+                         getLocationOfByte(startPos),
+                         /*IsStringLocation*/ true,
+                         getSpecifierRange(startPos, posLen));
   }
 }