[llvm-branch-commits] [llvm] [Support] Add an option to match each verify directive only once (PR #233699)

[Alexander Richardson via llvm-branch-commits]

https://github.com/arichardson updated https://github.com/llvm/llvm-project/pull/233699

>From d4d9c939281cc3df672bb2962fcf7279c5bf35f5 Mon Sep 17 00:00:00 2001
From: Alex Richardson <alexrichardson at google.com>
Date: Tue, 20 Oct 2026 14:56:06 -0700
Subject: [PATCH] [nspr] initial commit

---
 .../Support/SourceMgrDiagnosticVerifier.h     | 11 +++++++-
 .../Support/SourceMgrDiagnosticVerifier.cpp   |  7 +++--
 .../SourceMgrDiagnosticVerifierTest.cpp       | 28 +++++++++++++++++++
 3 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/llvm/include/llvm/Support/SourceMgrDiagnosticVerifier.h b/llvm/include/llvm/Support/SourceMgrDiagnosticVerifier.h
index 5ac34ad38a504..a9004b322a539 100644
--- a/llvm/include/llvm/Support/SourceMgrDiagnosticVerifier.h
+++ b/llvm/include/llvm/Support/SourceMgrDiagnosticVerifier.h
@@ -71,9 +71,15 @@ class LLVM_ABI SourceMgrDiagnosticVerifier {
   /// non-empty, directives are only recognized after the first occurrence of
   /// one of these strings on a line, so that text outside of comments is
   /// ignored.
+  ///
+  /// If \p oneDiagPerDirective is true, each directive matches at most one
+  /// diagnostic, as in Clang, so that a duplicated diagnostic is reported as
+  /// unexpected. Otherwise, a directive matches any number of identical
+  /// diagnostics on its line.
   SourceMgrDiagnosticVerifier(const SourceMgr &mgr, raw_ostream &os,
                               ArrayRef<StringRef> prefixes = {"expected"},
-                              ArrayRef<StringRef> commentPrefixes = {});
+                              ArrayRef<StringRef> commentPrefixes = {},
+                              bool oneDiagPerDirective = false);
 
   /// Matches a diagnostic against the expected diagnostics for \p loc, or
   /// against the '@unknown' expected diagnostics if \p loc is std::nullopt.
@@ -142,6 +148,9 @@ class LLVM_ABI SourceMgrDiagnosticVerifier {
   /// The strings that start a comment, see the constructor.
   SmallVector<std::string, 0> commentPrefixes;
 
+  /// Whether a directive can only match one diagnostic, see the constructor.
+  bool oneDiagPerDirective;
+
   /// The expected diagnostics for each buffer that has been scanned so far,
   /// keyed by buffer identifier (i.e. file name).
   StringMap<SmallVector<ExpectedDiag, 2>> expectedDiagsPerFile;
diff --git a/llvm/lib/Support/SourceMgrDiagnosticVerifier.cpp b/llvm/lib/Support/SourceMgrDiagnosticVerifier.cpp
index 1275016e9bfc0..59faacc901444 100644
--- a/llvm/lib/Support/SourceMgrDiagnosticVerifier.cpp
+++ b/llvm/lib/Support/SourceMgrDiagnosticVerifier.cpp
@@ -16,8 +16,8 @@ using namespace llvm;
 
 SourceMgrDiagnosticVerifier::SourceMgrDiagnosticVerifier(
     const SourceMgr &mgr, raw_ostream &os, ArrayRef<StringRef> prefixes,
-    ArrayRef<StringRef> commentPrefixes)
-    : mgr(mgr), os(os) {
+    ArrayRef<StringRef> commentPrefixes, bool oneDiagPerDirective)
+    : mgr(mgr), os(os), oneDiagPerDirective(oneDiagPerDirective) {
   assert(!prefixes.empty() && "must have at least one prefix");
   std::string prefixAlt;
   raw_string_ostream prefixOs(prefixAlt);
@@ -240,6 +240,9 @@ SourceMgrDiagnosticVerifier::process(SourceMgr::DiagKind kind,
     // File line must match (unless it's an unknown location).
     if (loc && e.lineNo != loc->lineNo)
       continue;
+    // A directive that already matched a diagnostic is used up.
+    if (oneDiagPerDirective && e.matched)
+      continue;
     if (e.match(message)) {
       if (e.kind == kind) {
         e.matched = true;
diff --git a/llvm/unittests/Support/SourceMgrDiagnosticVerifierTest.cpp b/llvm/unittests/Support/SourceMgrDiagnosticVerifierTest.cpp
index 034d181ac379f..794d2b68ce6f2 100644
--- a/llvm/unittests/Support/SourceMgrDiagnosticVerifierTest.cpp
+++ b/llvm/unittests/Support/SourceMgrDiagnosticVerifierTest.cpp
@@ -142,3 +142,31 @@ TEST_F(SourceMgrDiagnosticVerifierTest, CustomPrefixesAndCommentScoping) {
   EXPECT_TRUE(Verifier.verify());
   EXPECT_EQ(Output, "");
 }
+
+TEST_F(SourceMgrDiagnosticVerifierTest, DirectiveMatchesDuplicates) {
+  const MemoryBuffer *Buf = addBuffer("op\n# expected-error at -1 {{dup}}\n");
+  SourceMgrDiagnosticVerifier Verifier(SM, OS);
+
+  SMDiagnostic Dup = getMessage(Buf, SourceMgr::DK_Error, "dup");
+  EXPECT_EQ(Verifier.process(Dup), MatchResult::Matched);
+  EXPECT_EQ(Verifier.process(Dup), MatchResult::Matched);
+  EXPECT_TRUE(Verifier.verify());
+  EXPECT_EQ(Output, "");
+}
+
+TEST_F(SourceMgrDiagnosticVerifierTest, OneDiagPerDirective) {
+  const MemoryBuffer *Buf = addBuffer("op\n"
+                                      "# expected-error at -1 {{dup}}\n"
+                                      "# expected-error at -2 {{dup}}\n");
+  SourceMgrDiagnosticVerifier Verifier(SM, OS, {"expected"}, {},
+                                       /*oneDiagPerDirective=*/true);
+
+  // Each directive matches one diagnostic, so the third one is unexpected.
+  SMDiagnostic Dup = getMessage(Buf, SourceMgr::DK_Error, "dup");
+  EXPECT_EQ(Verifier.process(Dup), MatchResult::Matched);
+  EXPECT_EQ(Verifier.process(Dup), MatchResult::Matched);
+  EXPECT_EQ(Verifier.process(Dup), MatchResult::Unexpected);
+  EXPECT_FALSE(Verifier.verify());
+  EXPECT_EQ(StringRef(Output).count("error: dup"), 1u);
+  EXPECT_EQ(StringRef(Output).find("was not produced"), StringRef::npos);
+}