[clang] [llvm] [coverage] skipping code coverage for 'if constexpr' and 'if consteval' (PR #78033)

[Hana Dusíková via cfe-commits]

================
@@ -1700,43 +1776,116 @@ struct CounterCoverageMappingBuilder
     Visit(S->getSubStmt());
   }
 
+  void CoverIfConsteval(const IfStmt *S) {
+    assert(S->isConsteval());
+
+    const auto *Then = S->getThen();
+    const auto *Else = S->getElse();
+
+    // I'm using 'propagateCounts' later as new region is better and allows me
+    // to properly calculate line coverage in llvm-cov utility
+    const Counter ParentCount = getRegion().getCounter();
+
+    extendRegion(S);
+
+    if (S->isNegatedConsteval()) {
+      // ignore 'if consteval'
+      markSkipped(S->getIfLoc(), getStart(Then));
+      propagateCounts(ParentCount, Then);
+
+      if (Else) {
+        // ignore 'else <else>'
+        markSkipped(getEnd(Then), getEnd(Else));
+      }
+    } else {
+      assert(S->isNonNegatedConsteval());
+      // ignore 'if consteval <then> [else]'
+      markSkipped(S->getIfLoc(), Else ? getStart(Else) : getEnd(Then));
+
+      if (Else)
+        propagateCounts(ParentCount, Else);
+    }
+  }
+
+  void CoverIfConstexpr(const IfStmt *S) {
+    assert(S->isConstexpr());
+
+    // evaluate constant condition...
+    const auto *E = dyn_cast<ConstantExpr>(S->getCond());
+    assert(E != nullptr);
+    const bool isTrue = E->getResultAsAPSInt().getExtValue();
+
+    extendRegion(S);
+
+    const auto *Init = S->getInit();
+    const auto *Then = S->getThen();
+    const auto *Else = S->getElse();
+
+    // I'm using 'propagateCounts' later as new region is better and allows me
+    // to properly calculate line coverage in llvm-cov utility
+    const Counter ParentCount = getRegion().getCounter();
+
+    // ignore 'if constexpr ('
+    SourceLocation startOfSkipped = S->getIfLoc();
+
+    if (Init) {
+      // don't mark initialisation as ignored
+      markSkipped(startOfSkipped, getStart(Init));
+      propagateCounts(ParentCount, Init);
+      // ignore after initialisation: '; <condition>)'...
+      startOfSkipped = getEnd(Init);
----------------
hanickadot wrote:

yes, and it will be dealt as with declaration, in `propagateCounts` it will recurse into it

https://github.com/llvm/llvm-project/pull/78033