[clang-tidy/google-runtime-int] Allow passing non-bitwidth types to printf()-style APIs

Summary:
The `google-runtime-int` check currently fires on calls like:

  printf("%lu", (unsigned long)foo);

However, the style guide says:

> Where possible, avoid passing arguments of types specified by
> bitwidth typedefs to printf-based APIs.

http://google.github.io/styleguide/cppguide.html#64-bit_Portability

This diff relaxes the check to not fire on parameters to functions
with the `__format__` attribute. (I didn't specifically check
for `__printf__` since there are a few variations.)

Test Plan: New tests added. Ran tests with:
  % make -j16 check-clang-tools

Reviewers: alexfh, bkramer

Reviewed By: alexfh

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D46293

llvm-svn: 331268

2 files changed, 28 insertions, 1 deletions

diff --git a/clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp b/clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp
index f6c917c..7f0b765 100644
--- a/clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Basic/AttrKinds.h"
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/TargetInfo.h"
@@ -56,7 +57,16 @@ void IntegerTypesCheck::registerMatchers(MatchFinder *Finder) {
   // Find all TypeLocs. The relevant Style Guide rule only applies to C++.
   if (!getLangOpts().CPlusPlus)
     return;
-  Finder->addMatcher(typeLoc(loc(isInteger())).bind("tl"), this);
+  // Match any integer types, unless they are passed to a printf-based API:
+  //
+  // http://google.github.io/styleguide/cppguide.html#64-bit_Portability
+  // "Where possible, avoid passing arguments of types specified by
+  // bitwidth typedefs to printf-based APIs."
+  Finder->addMatcher(typeLoc(loc(isInteger()),
+                             unless(hasAncestor(callExpr(
+                                 callee(functionDecl(hasAttr(attr::Format)))))))
+                         .bind("tl"),
+                     this);
   IdentTable = llvm::make_unique<IdentifierTable>(getLangOpts());
 }
 
diff --git a/clang-tools-extra/test/clang-tidy/google-runtime-int.cpp b/clang-tools-extra/test/clang-tidy/google-runtime-int.cpp
index e51ca7d..4bb73987 100644
--- a/clang-tools-extra/test/clang-tidy/google-runtime-int.cpp
+++ b/clang-tools-extra/test/clang-tidy/google-runtime-int.cpp
@@ -72,3 +72,20 @@ void fff() {
   B a, b;
   a = b;
 }
+
+__attribute__((__format__ (__printf__, 1, 2)))
+void myprintf(const char* s, ...);
+
+void doprint_no_warning() {
+  uint64 foo = 23;
+  myprintf("foo %lu %lu", (unsigned long)42, (unsigned long)foo);
+}
+
+void myprintf_no_attribute(const char* s, ...);
+
+void doprint_warning() {
+  uint64 foo = 23;
+  myprintf_no_attribute("foo %lu %lu", (unsigned long)42, (unsigned long)foo);
+// CHECK-MESSAGES: [[@LINE-1]]:41: warning: consider replacing 'unsigned long'
+// CHECK-MESSAGES: [[@LINE-2]]:60: warning: consider replacing 'unsigned long'
+}