Precompile headers: Treat headers as relative to current source directory

Teach `target_precompile_headers` to treat relative paths the
same way as `target_sources`.

Fixes: #19733

1 files changed, 40 insertions, 1 deletions

diff --git a/Source/cmTargetPrecompileHeadersCommand.cxx b/Source/cmTargetPrecompileHeadersCommand.cxx
index 97f1bea..5751fff 100644
--- a/Source/cmTargetPrecompileHeadersCommand.cxx
+++ b/Source/cmTargetPrecompileHeadersCommand.cxx
@@ -2,17 +2,29 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmTargetPrecompileHeadersCommand.h"
 
+#include "cmGeneratorExpression.h"
 #include "cmMakefile.h"
 #include "cmMessageType.h"
 #include "cmStringAlgorithms.h"
+#include "cmSystemTools.h"
 #include "cmTarget.h"
 
+#include <utility>
+
 bool cmTargetPrecompileHeadersCommand::InitialPass(
   std::vector<std::string> const& args, cmExecutionStatus&)
 {
   return this->HandleArguments(args, "PRECOMPILE_HEADERS", PROCESS_REUSE_FROM);
 }
 
+void cmTargetPrecompileHeadersCommand::HandleInterfaceContent(
+  cmTarget* tgt, const std::vector<std::string>& content, bool prepend,
+  bool system)
+{
+  cmTargetPropCommandBase::HandleInterfaceContent(
+    tgt, ConvertToAbsoluteContent(tgt, content, true), prepend, system);
+}
+
 void cmTargetPrecompileHeadersCommand::HandleMissingTarget(
   const std::string& name)
 {
@@ -31,6 +43,33 @@ std::string cmTargetPrecompileHeadersCommand::Join(
 bool cmTargetPrecompileHeadersCommand::HandleDirectContent(
   cmTarget* tgt, const std::vector<std::string>& content, bool, bool)
 {
-  tgt->AppendProperty("PRECOMPILE_HEADERS", this->Join(content).c_str());
+  tgt->AppendProperty(
+    "PRECOMPILE_HEADERS",
+    this->Join(ConvertToAbsoluteContent(tgt, content, false)).c_str());
   return true;
 }
+
+std::vector<std::string>
+cmTargetPrecompileHeadersCommand::ConvertToAbsoluteContent(
+  cmTarget* /*tgt*/, const std::vector<std::string>& content,
+  bool /*isInterfaceContent*/)
+{
+  std::vector<std::string> absoluteContent;
+  absoluteContent.reserve(content.size());
+  for (std::string const& src : content) {
+    std::string absoluteSrc;
+    // Use '<foo.h>' and '"foo.h"' includes and absolute paths as-is.
+    // Interpret relative paths with respect to the source directory.
+    // If the path starts in a generator expression, assume it is absolute.
+    if (cmHasLiteralPrefix(src, "<") || cmHasLiteralPrefix(src, "\"") ||
+        cmSystemTools::FileIsFullPath(src) ||
+        cmGeneratorExpression::Find(src) == 0) {
+      absoluteSrc = src;
+    } else {
+      absoluteSrc =
+        cmStrCat(this->Makefile->GetCurrentSourceDirectory(), '/', src);
+    }
+    absoluteContent.emplace_back(std::move(absoluteSrc));
+  }
+  return absoluteContent;
+}