[analyzer] Fix -analyze-function debug warning to account for syntax checkers

[steakhal]

Previously, when using -analyze-function to target a specific function, the analyzer would incorrectly report "Every top-level function was skipped" even when the function was successfully analyzed by syntax-only checkers.

This happened because NumFunctionsAnalyzed only counted path-sensitive analysis, not syntax-only analysis. The misuse detection logic would see 0 functions analyzed and incorrectly conclude the function wasn't found.

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-static-analyzer-1

Author: Balazs Benics (steakhal)

Changes

Previously, when using -analyze-function to target a specific function, the analyzer would incorrectly report "Every top-level function was skipped" even when the function was successfully analyzed by syntax-only checkers.

This happened because NumFunctionsAnalyzed only counted path-sensitive analysis, not syntax-only analysis. The misuse detection logic would see 0 functions analyzed and incorrectly conclude the function wasn't found.

---

Full diff: https://github.com/llvm/llvm-project/pull/161664.diff

2 Files Affected:

• (modified) clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp (+7-3)
• (modified) clang/test/Analysis/analyze-function-guide.cpp (+11-8)

diff --git a/clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp b/clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
index 53466e7a75b0f..5906e876aa311 100644
--- a/clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
+++ b/clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
@@ -51,6 +51,9 @@ STAT_COUNTER(NumFunctionTopLevel, "The # of functions at top level.");
 ALWAYS_ENABLED_STATISTIC(NumFunctionsAnalyzed,
                          "The # of functions and blocks analyzed (as top level "
                          "with inlining turned on).");
+ALWAYS_ENABLED_STATISTIC(
+    NumFunctionsAnalyzedSyntaxOnly,
+    "The # of functions analyzed by syntax checkers only.");
 ALWAYS_ENABLED_STATISTIC(NumBlocksInAnalyzedFunctions,
                          "The # of basic blocks in the analyzed functions.");
 ALWAYS_ENABLED_STATISTIC(
@@ -588,10 +591,10 @@ void AnalysisConsumer::runAnalysisOnTranslationUnit(ASTContext &C) {
   // If the user wanted to analyze a specific function and the number of basic
   // blocks analyzed is zero, than the user might not specified the function
   // name correctly.
-  // FIXME: The user might have analyzed the requested function in Syntax mode,
-  // but we are unaware of that.
-  if (!Opts.AnalyzeSpecificFunction.empty() && NumFunctionsAnalyzed == 0)
+  if (!Opts.AnalyzeSpecificFunction.empty() && NumFunctionsAnalyzed == 0 &&
+      NumFunctionsAnalyzedSyntaxOnly == 0) {
     reportAnalyzerFunctionMisuse(Opts, *Ctx);
+  }
 }
 
 void AnalysisConsumer::reportAnalyzerProgress(StringRef S) {
@@ -723,6 +726,7 @@ void AnalysisConsumer::HandleCode(Decl *D, AnalysisMode Mode,
       SyntaxCheckTimer->startTimer();
     }
     checkerMgr->runCheckersOnASTBody(D, *Mgr, BR);
+    ++NumFunctionsAnalyzedSyntaxOnly;
     if (SyntaxCheckTimer) {
       SyntaxCheckTimer->stopTimer();
       llvm::TimeRecord CheckerEndTime = SyntaxCheckTimer->getTotalTime();
diff --git a/clang/test/Analysis/analyze-function-guide.cpp b/clang/test/Analysis/analyze-function-guide.cpp
index 96f1001057eb6..e260fc43a666a 100644
--- a/clang/test/Analysis/analyze-function-guide.cpp
+++ b/clang/test/Analysis/analyze-function-guide.cpp
@@ -46,14 +46,17 @@ int fizzbuzz(int x, bool y) {
 // CHECK-ADVOCATE-DISPLAY-PROGRESS-NEXT: Pass the -analyzer-display-progress for tracking which functions are analyzed.
 // CHECK-ADVOCATE-DISPLAY-PROGRESS-NOT:  For analyzing
 
-// Same as the previous but syntax mode only.
-// FIXME: This should have empty standard output.
+// The user only enables syntax-only analysis, like `debug.DumpDominators`.
+// `-analyze-function` should only match the given function.
 //
-// RUN: %clang_analyze_cc1 -analyzer-checker=core -analyzer-config ipa=none \
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.DumpDominators -analyzer-config ipa=none \
 // RUN:   -analyze-function='fizzbuzz(int, _Bool)' -x c++ \
 // RUN:   -triple x86_64-pc-linux-gnu 2>&1 %s \
-// RUN: | FileCheck %s -check-prefix=CHECK-EMPTY3 --allow-empty
-//
-// FIXME: This should have empty standard output.
-// CHECK-EMPTY3:      Every top-level function was skipped.
-// CHECK-EMPTY3-NEXT: Pass the -analyzer-display-progress for tracking which functions are analyzed.
+// RUN: | FileCheck %s -check-prefix=CHECK-SYNTAX-ONLY --allow-empty
+//
+// With syntax-only analysis, the function is found and analyzed, so no error message.
+// CHECK-SYNTAX-ONLY:      Immediate dominance tree (Node#,IDom#):
+// CHECK-SYNTAX-ONLY-NEXT: (0,1)
+// CHECK-SYNTAX-ONLY-NEXT: (1,2)
+// CHECK-SYNTAX-ONLY-NEXT: (2,2)
+// CHECK-SYNTAX-ONLY-NOT: Every top-level function was skipped.

[llvm-ci]

LLVM Buildbot has detected a new failure on builder ppc64le-flang-rhel-clang running on ppc64le-flang-rhel-test while building clang at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/157/builds/41172

Here is the relevant piece of the build log for the reference

Step 5 (build-unified-tree) failure: build (failure) (timed out)
...
111.864 [3/10/120] Building CXX object flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/reduction.cpp.o
122.202 [3/9/121] Building CXX object flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/reduce.cpp.o
124.519 [3/8/122] Building CXX object flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/tools.cpp.o
168.011 [3/7/123] Building CXX object flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/character.cpp.o
205.187 [3/6/124] Building CXX object flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/dot-product.cpp.o
570.021 [3/5/125] Building CXX object flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/matmul-transpose.cpp.o
677.682 [3/4/126] Building CXX object flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/extrema.cpp.o
689.940 [3/3/127] Building CXX object flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/matmul.cpp.o
846.458 [3/2/128] Building CXX object flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/findloc.cpp.o
846.686 [2/2/129] Linking CXX static library /home/buildbots/llvm-external-buildbots/workers/ppc64le-flang-rhel-test/ppc64le-flang-rhel-clang-build/build/lib/clang/22/lib/powerpc64le-unknown-linux-gnu/libflang_rt.runtime.a
command timed out: 1200 seconds without output running [b'ninja'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=2869.635664