install: Teach CODE,SCRIPT modes to evaluate generator expressions

This also introduces CMP0087 which will keep the OLD behaviour of not
evaluating generator expressions

Fixes: #15785

3 files changed, 78 insertions, 12 deletions

diff --git a/Source/cmInstallScriptGenerator.cxx b/Source/cmInstallScriptGenerator.cxx
index 7d77b7c..b93debb 100644
--- a/Source/cmInstallScriptGenerator.cxx
+++ b/Source/cmInstallScriptGenerator.cxx
@@ -2,11 +2,15 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmInstallScriptGenerator.h"
 
-#include "cmScriptGenerator.h"
-
 #include <ostream>
 #include <vector>
 
+#include "cmGeneratorExpression.h"
+#include "cmLocalGenerator.h"
+#include "cmPolicies.h"
+#include "cmScriptGenerator.h"
+#include "cmake.h"
+
 cmInstallScriptGenerator::cmInstallScriptGenerator(const char* script,
                                                    bool code,
                                                    const char* component,
@@ -15,25 +19,71 @@ cmInstallScriptGenerator::cmInstallScriptGenerator(const char* script,
                        MessageDefault, exclude_from_all)
   , Script(script)
   , Code(code)
+  , AllowGenex(false)
 {
+  // We need per-config actions if the script has generator expressions.
+  if (cmGeneratorExpression::Find(Script) != std::string::npos) {
+    this->ActionsPerConfig = true;
+  }
 }
 
 cmInstallScriptGenerator::~cmInstallScriptGenerator()
 {
 }
 
-void cmInstallScriptGenerator::GenerateScript(std::ostream& os)
+void cmInstallScriptGenerator::Compute(cmLocalGenerator* lg)
 {
-  Indent indent;
-  std::string component_test =
-    this->CreateComponentTest(this->Component.c_str(), this->ExcludeFromAll);
-  os << indent << "if(" << component_test << ")\n";
+  this->LocalGenerator = lg;
 
+  if (this->ActionsPerConfig) {
+    switch (this->LocalGenerator->GetPolicyStatus(cmPolicies::CMP0087)) {
+      case cmPolicies::WARN:
+        this->LocalGenerator->IssueMessage(
+          cmake::AUTHOR_WARNING,
+          cmPolicies::GetPolicyWarning(cmPolicies::CMP0087));
+        CM_FALLTHROUGH;
+      case cmPolicies::OLD:
+        break;
+      case cmPolicies::NEW:
+      case cmPolicies::REQUIRED_ALWAYS:
+      case cmPolicies::REQUIRED_IF_USED:
+        this->AllowGenex = true;
+        break;
+    }
+  }
+}
+
+void cmInstallScriptGenerator::AddScriptInstallRule(std::ostream& os,
+                                                    Indent indent,
+                                                    std::string const& script)
+{
   if (this->Code) {
-    os << indent << this->Script << "\n";
+    os << indent << script << "\n";
   } else {
-    os << indent << "include(\"" << this->Script << "\")\n";
+    os << indent << "include(\"" << script << "\")\n";
   }
+}
 
-  os << indent << "endif()\n\n";
+void cmInstallScriptGenerator::GenerateScriptActions(std::ostream& os,
+                                                     Indent indent)
+{
+  if (this->AllowGenex && this->ActionsPerConfig) {
+    this->cmInstallGenerator::GenerateScriptActions(os, indent);
+  } else {
+    this->AddScriptInstallRule(os, indent, this->Script);
+  }
+}
+
+void cmInstallScriptGenerator::GenerateScriptForConfig(
+  std::ostream& os, const std::string& config, Indent indent)
+{
+  if (this->AllowGenex) {
+    cmGeneratorExpression ge;
+    std::unique_ptr<cmCompiledGeneratorExpression> cge =
+      ge.Parse(this->Script);
+    this->AddScriptInstallRule(os, indent,
+                               cge->Evaluate(this->LocalGenerator, config));
+  } else {
+    this->AddScriptInstallRule(os, indent, this->Script);
+  }
 }
diff --git a/Source/cmInstallScriptGenerator.h b/Source/cmInstallScriptGenerator.h
index fe0f7c6..05199d7 100644
--- a/Source/cmInstallScriptGenerator.h
+++ b/Source/cmInstallScriptGenerator.h
@@ -6,10 +6,13 @@
 #include "cmConfigure.h" // IWYU pragma: keep
 
 #include "cmInstallGenerator.h"
+#include "cmScriptGenerator.h"
 
 #include <iosfwd>
 #include <string>
 
+class cmLocalGenerator;
+
 /** \class cmInstallScriptGenerator
  * \brief Generate target installation rules.
  */
@@ -20,10 +23,19 @@ public:
                            const char* component, bool exclude_from_all);
   ~cmInstallScriptGenerator() override;
 
+  void Compute(cmLocalGenerator* lg) override;
+
 protected:
-  void GenerateScript(std::ostream& os) override;
+  void GenerateScriptActions(std::ostream& os, Indent indent) override;
+  void GenerateScriptForConfig(std::ostream& os, const std::string& config,
+                               Indent indent) override;
+  void AddScriptInstallRule(std::ostream& os, Indent indent,
+                            std::string const& script);
+
   std::string Script;
   bool Code;
+  cmLocalGenerator* LocalGenerator;
+  bool AllowGenex;
 };
 
 #endif
diff --git a/Source/cmPolicies.h b/Source/cmPolicies.h
index 7674877..206dd3d 100644
--- a/Source/cmPolicies.h
+++ b/Source/cmPolicies.h
@@ -254,7 +254,11 @@ class cmMakefile;
          0, cmPolicies::WARN)                                                 \
   SELECT(POLICY, CMP0086,                                                     \
          "UseSWIG honors SWIG_MODULE_NAME via -module flag.", 3, 14, 0,       \
-         cmPolicies::WARN)
+         cmPolicies::WARN)                                                    \
+  SELECT(POLICY, CMP0087,                                                     \
+         "Install CODE|SCRIPT allow the use of generator "                    \
+         "expressions.",                                                      \
+         3, 14, 0, cmPolicies::WARN)
 
 #define CM_SELECT_ID(F, A1, A2, A3, A4, A5, A6) F(A1)
 #define CM_FOR_EACH_POLICY_ID(POLICY)                                         \