[PATCH] D144011: [clang]Fix warning for signed conversion

[Yaxun Liu via Phabricator via cfe-commits]

yaxunl updated this revision to Diff 497703.
yaxunl added a comment.

revised by Fanrui's comments


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D144011/new/

https://reviews.llvm.org/D144011

Files:
  clang/lib/Sema/SemaChecking.cpp
  clang/test/Sema/sign-conversion.c


Index: clang/test/Sema/sign-conversion.c
===================================================================
--- clang/test/Sema/sign-conversion.c
+++ clang/test/Sema/sign-conversion.c
@@ -5,4 +5,8 @@
 void test(int x) {
   unsigned t0 = x; // expected-warning {{implicit conversion changes 
signedness}}
   unsigned t1 = (t0 == 5 ? x : 0); // expected-warning {{operand of ? changes 
signedness}}
+
+  // Clang has special treatment for left shift of literal '1'.
+  // Make sure there is no diagnostics.
+  long t2 = 1LL << x;
 }
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -14293,6 +14293,12 @@
     if (S.SourceMgr.isInSystemMacro(CC))
       return;
 
+    if (SourceBT && SourceBT->isInteger() && TargetBT &&
+        TargetBT->isInteger() &&
+        Source->isSignedIntegerType() == Target->isSignedIntegerType()) {
+      return;
+    }
+
     unsigned DiagID = diag::warn_impcast_integer_sign;
 
     // Traditionally, gcc has warned about this under -Wsign-compare.



Index: clang/test/Sema/sign-conversion.c
===================================================================
--- clang/test/Sema/sign-conversion.c
+++ clang/test/Sema/sign-conversion.c
@@ -5,4 +5,8 @@
 void test(int x) {
   unsigned t0 = x; // expected-warning {{implicit conversion changes signedness}}
   unsigned t1 = (t0 == 5 ? x : 0); // expected-warning {{operand of ? changes signedness}}
+
+  // Clang has special treatment for left shift of literal '1'.
+  // Make sure there is no diagnostics.
+  long t2 = 1LL << x;
 }
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -14293,6 +14293,12 @@
     if (S.SourceMgr.isInSystemMacro(CC))
       return;
 
+    if (SourceBT && SourceBT->isInteger() && TargetBT &&
+        TargetBT->isInteger() &&
+        Source->isSignedIntegerType() == Target->isSignedIntegerType()) {
+      return;
+    }
+
     unsigned DiagID = diag::warn_impcast_integer_sign;
 
     // Traditionally, gcc has warned about this under -Wsign-compare.

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