[clang] 5d92d0b - Correctly diagnose use of long long literals w/o a suffix

[Aaron Ballman via cfe-commits]

Author: Aaron Ballman
Date: 2022-09-17T07:55:10-04:00
New Revision: 5d92d0b0f86c2c4e0c6ebd7b1e2113337fec041d

URL: https://github.com/llvm/llvm-project/commit/5d92d0b0f86c2c4e0c6ebd7b1e2113337fec041d
DIFF: https://github.com/llvm/llvm-project/commit/5d92d0b0f86c2c4e0c6ebd7b1e2113337fec041d.diff

LOG: Correctly diagnose use of long long literals w/o a suffix

We would diagnose use of `long long` as an extension in C89 and C++98
modes when the user spelled the type `long long` or used the `LL`
literal suffix, but failed to diagnose when the literal had no suffix
but required a `long long` to represent the value.

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Sema/SemaExpr.cpp
    clang/test/C/drs/dr2xx.c
    clang/test/CXX/drs/dr4xx.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index ccc3204edd2d2..4c251d1dc6ed7 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -168,6 +168,10 @@ Improvements to Clang's diagnostics
   conditional operator, and for most binary operations. Type sugar is combined
   in a way that strips the sugar which is 
diff erent between terms, and preserves
   those which are common.
+- Correctly diagnose use of an integer literal without a suffix whose
+  underlying type is ``long long`` or ``unsigned long long`` as an extension in
+  C89 mode . Clang previously only diagnosed if the literal had an explicit
+  ``LL`` suffix.
 
 Non-comprehensive list of changes in this release
 -------------------------------------------------

diff  --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 348eaad3dee94..e53c88b283b87 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -3937,16 +3937,6 @@ ExprResult Sema::ActOnNumericConstant(const Token &Tok, Scope *UDLScope) {
   } else {
     QualType Ty;
 
-    // 'long long' is a C99 or C++11 feature.
-    if (!getLangOpts().C99 && Literal.isLongLong) {
-      if (getLangOpts().CPlusPlus)
-        Diag(Tok.getLocation(),
-             getLangOpts().CPlusPlus11 ?
-             diag::warn_cxx98_compat_longlong : diag::ext_cxx11_longlong);
-      else
-        Diag(Tok.getLocation(), diag::ext_c99_longlong);
-    }
-
     // 'z/uz' literals are a C++2b feature.
     if (Literal.isSizeT)
       Diag(Tok.getLocation(), getLangOpts().CPlusPlus
@@ -4113,6 +4103,15 @@ ExprResult Sema::ActOnNumericConstant(const Token &Tok, Scope *UDLScope) {
           else if (AllowUnsigned)
             Ty = Context.UnsignedLongLongTy;
           Width = LongLongSize;
+
+          // 'long long' is a C99 or C++11 feature, whether the literal
+          // explicitly specified 'long long' or we needed the extra width.
+          if (getLangOpts().CPlusPlus)
+            Diag(Tok.getLocation(), getLangOpts().CPlusPlus11
+                                        ? diag::warn_cxx98_compat_longlong
+                                        : diag::ext_cxx11_longlong);
+          else if (!getLangOpts().C99)
+            Diag(Tok.getLocation(), diag::ext_c99_longlong);
         }
       }
 

diff  --git a/clang/test/C/drs/dr2xx.c b/clang/test/C/drs/dr2xx.c
index 6b87aace6a910..95d8eefaa2a99 100644
--- a/clang/test/C/drs/dr2xx.c
+++ b/clang/test/C/drs/dr2xx.c
@@ -448,9 +448,11 @@ void dr298(void) {
   /* FIXME: These uses of the constants need a pedantic warning in C89 mode;
    * we've picked a type that does not exist in C89.
    */
-  (void)_Generic(9223372036854775808,     /* expected-warning {{integer literal is too large to be represented in a signed integer type, interpreting as unsigned}} */
+  (void)_Generic(9223372036854775808,     /* expected-warning {{integer literal is too large to be represented in a signed integer type, interpreting as unsigned}}
+                                             c89only-warning {{'long long' is an extension when C99 mode is not enabled}}
+                                           */
                  unsigned long long : 1); /* c89only-warning {{'long long' is an extension when C99 mode is not enabled}} */
-  (void)_Generic(9223372036854775807,
+  (void)_Generic(9223372036854775807,     /* c89only-warning {{'long long' is an extension when C99 mode is not enabled}} */
                  long long : 1);          /* c89only-warning {{'long long' is an extension when C99 mode is not enabled}} */
 }
 #endif /* __LLONG_WIDTH__ == 64 && __LONG_WIDTH__ < 64 */

diff  --git a/clang/test/CXX/drs/dr4xx.cpp b/clang/test/CXX/drs/dr4xx.cpp
index 16957dd9d0e39..4995e4de65d3f 100644
--- a/clang/test/CXX/drs/dr4xx.cpp
+++ b/clang/test/CXX/drs/dr4xx.cpp
@@ -1013,7 +1013,7 @@ namespace dr483 { // dr483: yes
     int check4[__LONG_MAX__ >= 2147483647 ? 1 : -1];
     int check5[__LONG_LONG_MAX__ >= 9223372036854775807 ? 1 : -1];
 #if __cplusplus < 201103L
-    // expected-error at -2 {{extension}}
+    // expected-error at -2 2{{extension}}
 #endif
   }
   namespace cstdint {