[analyzer][ctu] fix unsortable diagnostics

[r.stahl]

Summary

In the provided test case the PathDiagnostic compare function was not able to find a difference.

[r.stahl]

In D30691#879838, @xazax.hun wrote:

In D30691#878830, @r.stahl wrote:

For my purposes I replaced the return statement of the compareCrossTUSourceLocs function with:

return XL.getFileID() < YL.getFileID();

A more correct fix would create only one unique diagnostic for both cases.

Thank you for the report, I could reproduce this after modifying the null dereference checker. My fear of using file IDs is that I don't know whether they are stable. So in subsequent runs, different paths might be chosen by the analyzer and this could be confusing to the user. I will think about a workaround that both stable and solves this assertion.

I see two possible ways to do the proper fix. One is to check explicitly for this case when the same function appears in multiple translation units. A better approach would be to have the ASTImporter handle this case. I think the proper fix is better addressed in a separate patch.

Here is my improper fix with test case. Since CTU is still an experimental feature and this is a rare case to encounter I believe it's okay to risk confusing the user, rather than keep it broken.

Unfortunately I will not have the time to work on a proper fix.

[george.karpenkov]

My fear of using file IDs is that I don't know whether they are stable

IIRC they are currently stable, but that's relying on implementation details.
Still better than not differentiating at all.

lib/StaticAnalyzer/Core/PathDiagnostic.cpp

 
 static bool compareCrossTUSourceLocs(FullSourceLoc XL, FullSourceLoc YL) {
   std::pair<FileID, unsigned> XOffs = XL.getDecomposedLoc();
   std::pair<FileID, unsigned> YOffs = YL.getDecomposedLoc();
   const SourceManager &SM = XL.getManager();
   std::pair<bool, bool> InSameTU = SM.isInTheSameTranslationUnit(XOffs, YOffs);
   if (InSameTU.first)
     return XL.isBeforeInTranslationUnitThan(YL);
-  const FileEntry *XFE = SM.getFileEntryForID(XL.getFileID());
-  const FileEntry *YFE = SM.getFileEntryForID(YL.getFileID());
+  const FileEntry *XFE = SM.getFileEntryForID(XL.getSpellingLoc().getFileID());
+  const FileEntry *YFE = SM.getFileEntryForID(YL.getSpellingLoc().getFileID());
   if (!XFE || !YFE)
     return XFE && !YFE;
-  return XFE->getName() < YFE->getName();
+  int NameCmp = XFE->getName().compare(YFE->getName());
+  if (NameCmp != 0)
+    return NameCmp == -1;
+  // Last resort: Compare raw file IDs that are possibly expansions.
+  return XL.getFileID() < YL.getFileID();
 }
 
 static bool compare(const PathDiagnostic &X, const PathDiagnostic &Y) {
   FullSourceLoc XL = X.getLocation().asLocation();
   FullSourceLoc YL = Y.getLocation().asLocation();
   if (XL != YL)
     return compareCrossTUSourceLocs(XL, YL);
   if (X.getBugType() != Y.getBugType())

test/Analysis/Inputs/ctu-other.cpp

+#include "../ctu-hdr.h"
+
 int callback_to_main(int x);
 int f(int x) {
   return x - 1;
 }
 
 int g(int x) {
   return callback_to_main(x) + 1;
 }

 
 int chf1(int x) {
   return chf2(x);
 }
 }
 
 typedef struct { int n; } Anonymous;
 int fun_using_anon_struct(int n) { Anonymous anon; anon.n = n; return anon.n; }
+
+int other_macro_diag(int x) {
+  MACRODIAG();
+  return x;
+}

test/Analysis/Inputs/externalFnMap.txt

 c:@N@chns@F@chf1#I# ctu-other.cpp.ast
 c:@N@myns@N@embed_ns@F@fens#I# ctu-other.cpp.ast
 c:@F@g#I# ctu-other.cpp.ast
 c:@S@mycls@F@fscl#I#S ctu-other.cpp.ast
 c:@S@mycls@F@fcl#I# ctu-other.cpp.ast
 c:@N@myns@S@embed_cls@F@fecl#I# ctu-other.cpp.ast
 c:@S@mycls@S@embed_cls2@F@fecl2#I# ctu-other.cpp.ast
 c:@F@f#I# ctu-other.cpp.ast
 c:@N@myns@F@fns#I# ctu-other.cpp.ast
 c:@F@h#I# ctu-other.cpp.ast
 c:@F@h_chain#I# ctu-chain.cpp.ast
 c:@N@chns@S@chcls@F@chf4#I# ctu-chain.cpp.ast
 c:@N@chns@F@chf2#I# ctu-chain.cpp.ast
 c:@F@fun_using_anon_struct#I# ctu-other.cpp.ast
+c:@F@other_macro_diag#I# ctu-other.cpp.ast

test/Analysis/ctu-hdr.h

+#define MACRODIAG() clang_analyzer_warnIfReached()
+
+void clang_analyzer_warnIfReached();

test/Analysis/ctu-main.cpp

 // RUN: mkdir -p %T/ctudir
 // RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -emit-pch -o %T/ctudir/ctu-other.cpp.ast %S/Inputs/ctu-other.cpp
 // RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -emit-pch -o %T/ctudir/ctu-chain.cpp.ast %S/Inputs/ctu-chain.cpp
 // RUN: cp %S/Inputs/externalFnMap.txt %T/ctudir/
 // RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fsyntax-only -analyze -analyzer-checker=core,debug.ExprInspection -analyzer-config experimental-enable-naive-ctu-analysis=true -analyzer-config ctu-dir=%T/ctudir -verify %s
 
+#include "ctu-hdr.h"
+
 void clang_analyzer_eval(int);
 
 int f(int);
 int g(int);
 int h(int);
 
 int callback_to_main(int x) { return x + 1; }
 
public:
   };
 };
 
 namespace chns {
 int chf1(int x);
 }
 
 int fun_using_anon_struct(int);
+int other_macro_diag(int);
 
 int main() {
   clang_analyzer_eval(f(3) == 2); // expected-warning{{TRUE}}
   clang_analyzer_eval(f(4) == 3); // expected-warning{{TRUE}}
   clang_analyzer_eval(f(5) == 3); // expected-warning{{FALSE}}
   clang_analyzer_eval(g(4) == 6); // expected-warning{{TRUE}}
   clang_analyzer_eval(h(2) == 8); // expected-warning{{TRUE}}
 
   clang_analyzer_eval(myns::fns(2) == 9);                   // expected-warning{{TRUE}}
   clang_analyzer_eval(myns::embed_ns::fens(2) == -1);       // expected-warning{{TRUE}}
   clang_analyzer_eval(mycls().fcl(1) == 6);                 // expected-warning{{TRUE}}
   clang_analyzer_eval(mycls::fscl(1) == 7);                 // expected-warning{{TRUE}}
   clang_analyzer_eval(myns::embed_cls().fecl(1) == -6);     // expected-warning{{TRUE}}
   clang_analyzer_eval(mycls::embed_cls2().fecl2(0) == -11); // expected-warning{{TRUE}}
 
   clang_analyzer_eval(chns::chf1(4) == 12); // expected-warning{{TRUE}}
   clang_analyzer_eval(fun_using_anon_struct(8) == 8); // expected-warning{{TRUE}}
+
+  clang_analyzer_eval(other_macro_diag(1) == 1); // expected-warning{{TRUE}}
+  // expected-warning@Inputs/ctu-other.cpp:75{{REACHABLE}}
+  MACRODIAG(); // expected-warning{{REACHABLE}}
 }