From 5871128ed85626f2475aea4b725e955f455a4d1a Mon Sep 17 00:00:00 2001
From: "nv-slang-bot[bot]"
 <274397474+nv-slang-bot[bot]@users.noreply.github.com>
Date: Thu, 4 Jun 2026 19:12:42 +0000
Subject: [PATCH] slang-preprocessor: keep absoluteSourceLocCounter monotonic
 across __include passes

Each `__include`d file is preprocessed in a fresh `preprocessSource`
pass that constructs a new Preprocessor with absoluteSourceLocCounter
defaulting to 0. The shared sink-attached WarningStateTracker keys
its per-id timelines by absolute SourceLoc, so colliding 0-bases
from different files break the timeline ordering: a `#pragma
warning(pop)` in a later __include'd file blanket-restores every
known id by looking up findEntry(pushedLocation), which under
collisions misses the root-TU disable and reverts the id to
Default. The user's root-level `#pragma warning(disable: 30856)`
then no longer applies on subsequent emissions.

Carry the high-water mark of absoluteSourceLocCounter across
passes via the already-shared WarningStateTracker. Every later
pass's locations land strictly after the prior pass's max, so the
timeline binary search finds the correct push-time entry and the
root disable survives. The internal timeline logic is unchanged.

Fixes #11473
---
 source/slang/slang-preprocessor.cpp           | 33 +++++++++++++++++++
 ...ragma-warning-include-empty-pop-body.slang |  9 +++++
 ...gma-warning-include-empty-pop-footer.slang |  5 +++
 ...ragma-warning-include-empty-pop-main.slang | 10 ++++++
 4 files changed, 57 insertions(+)
 create mode 100644 tests/diagnostics/pragma-warning-include-empty-pop-body.slang
 create mode 100644 tests/diagnostics/pragma-warning-include-empty-pop-footer.slang
 create mode 100644 tests/diagnostics/pragma-warning-include-empty-pop-main.slang

diff --git a/source/slang/slang-preprocessor.cpp b/source/slang/slang-preprocessor.cpp
index 6e79511b719..3129fd403aa 100644
--- a/source/slang/slang-preprocessor.cpp
+++ b/source/slang/slang-preprocessor.cpp
@@ -1191,6 +1191,16 @@ struct WarningStateTracker : SourceWarningStateTrackerBase
     Dictionary<int, WarningTimeline> mapDiagnosticIdToTimeline = {};
     List<SourceLoc> stack = {};
 
+    // High-water mark of `Preprocessor::absoluteSourceLocCounter`, carried
+    // across the multiple `preprocessSource` passes that share this tracker
+    // within a single translation unit (one pass for the root file plus one
+    // per `__include`d module file). Each pass seeds its preprocessor counter
+    // from this value at start and writes the new high-water mark back at
+    // end, so absolute locations across passes stay strictly monotonic and
+    // the per-id timeline binary search continues to find the correct push
+    // entry for a `#pragma warning(pop)`.
+    SourceLoc::RawValue absoluteLocCounter = 0;
+
     WarningStateTracker(SourceManager* sourceManager = nullptr)
         : sourceManager(sourceManager)
     {
@@ -5028,6 +5038,19 @@ TokenList preprocessSource(
     preprocessor.warningStateTracker =
         dynamicCast<preprocessor::WarningStateTracker>(desc.sink->getSourceWarningStateTracker());
 
+    // Seed the absolute-loc counter from the shared per-TU tracker so that
+    // locations produced by this pass are strictly larger than any location
+    // produced by earlier passes (root file + previously processed
+    // `__include`d files). Without this, every pass starts at 0 and the
+    // pragma warning timelines (keyed by absolute loc) collide across files,
+    // which can cause `#pragma warning(pop)` in one included file to
+    // silently revert a `#pragma warning(disable: <id>)` in another file.
+    if (preprocessor.warningStateTracker)
+    {
+        preprocessor.absoluteSourceLocCounter =
+            preprocessor.warningStateTracker->absoluteLocCounter;
+    }
+
     // Add builtin macros
     {
         auto namePool = desc.namePool;
@@ -5111,6 +5134,16 @@ TokenList preprocessSource(
     outDetectedLanguage = preprocessor.language;
     if (preprocessor.languageVersion != SLANG_LANGUAGE_VERSION_UNKNOWN)
         outLanguageVersion = preprocessor.languageVersion;
+
+    // Carry the high-water mark forward so the next `preprocessSource` pass
+    // for this translation unit (e.g. an `__include`d module file) starts
+    // its absolute locations strictly after ours.
+    if (preprocessor.warningStateTracker)
+    {
+        preprocessor.warningStateTracker->absoluteLocCounter =
+            preprocessor.absoluteSourceLocCounter;
+    }
+
     return tokens;
 }
 
diff --git a/tests/diagnostics/pragma-warning-include-empty-pop-body.slang b/tests/diagnostics/pragma-warning-include-empty-pop-body.slang
new file mode 100644
index 00000000000..1e22395e402
--- /dev/null
+++ b/tests/diagnostics/pragma-warning-include-empty-pop-body.slang
@@ -0,0 +1,9 @@
+implementing pragma_warning_include_empty_pop;
+
+namespace body_ns
+{
+    interface IConvertibleFrom<From> {}
+
+    extension<From : __BuiltinIntegerType, To : IConvertibleFrom<From>, let N : int>
+    vector<To, N> : IConvertibleFrom<vector<From, N>> {}
+}
diff --git a/tests/diagnostics/pragma-warning-include-empty-pop-footer.slang b/tests/diagnostics/pragma-warning-include-empty-pop-footer.slang
new file mode 100644
index 00000000000..d155173283b
--- /dev/null
+++ b/tests/diagnostics/pragma-warning-include-empty-pop-footer.slang
@@ -0,0 +1,5 @@
+implementing pragma_warning_include_empty_pop;
+
+#pragma warning(push)
+#pragma warning(disable: 31000)
+#pragma warning(pop)
diff --git a/tests/diagnostics/pragma-warning-include-empty-pop-main.slang b/tests/diagnostics/pragma-warning-include-empty-pop-main.slang
new file mode 100644
index 00000000000..801fd89257d
--- /dev/null
+++ b/tests/diagnostics/pragma-warning-include-empty-pop-main.slang
@@ -0,0 +1,10 @@
+//TEST:SIMPLE(filecheck=CHECK):
+
+module pragma_warning_include_empty_pop;
+
+#pragma warning(disable: 30856)
+
+__include "pragma-warning-include-empty-pop-body.slang";
+__include "pragma-warning-include-empty-pop-footer.slang";
+
+// CHECK-NOT: warning 30856