Detect PICO_COMPILER automatically when PICO_TOOLCHAIN_PATH is set

Author: kilograham

cmake/pico_pre_load_toolchain.cmake

@@ -1,4 +1,7 @@
 # PICO_CMAKE_CONFIG: PICO_TOOLCHAIN_PATH, Path to search for compiler, type=string, default=none (i.e. search system paths), group=build, docref=cmake-toolchain-config
+if (NOT PICO_TOOLCHAIN_PATH AND DEFINED ENV{PICO_TOOLCHAIN_PATH})
+    set(PICO_TOOLCHAIN_PATH $ENV{PICO_TOOLCHAIN_PATH})
+endif()
 set(PICO_TOOLCHAIN_PATH "${PICO_TOOLCHAIN_PATH}" CACHE INTERNAL "")
 
 # Set a default build type if none was specified
@@ -19,13 +22,30 @@ if (CMAKE_BUILD_TYPE STREQUAL "Default")
 endif()
 
 if (NOT (DEFINED PICO_COMPILER OR DEFINED CMAKE_TOOLCHAIN_FILE))
-    if (DEFINED PICO_DEFAULT_COMPILER)
-        pico_message("Defaulting compiler (PICO_COMPILER) to '${PICO_DEFAULT_COMPILER}' since not specified.")
+    if (PICO_TOOLCHAIN_PATH)
+        if (PICO_DEFAULT_GCC_COMPILER)
+            FILE(GLOB _COMPILER "${PICO_TOOLCHAIN_PATH}/bin/*gcc*")
+            if (_COMPILER)
+                set(PICO_COMPILER ${PICO_DEFAULT_GCC_COMPILER})
+                message("Detected GCC so defaulting PICO_COMPILER to `${PICO_COMPILER}`")
+            endif()
+        endif()
+        if (NOT PICO_COMPILER AND PICO_DEFAULT_CLANG_COMPILER)
+            FILE(GLOB _COMPILER "${PICO_TOOLCHAIN_PATH}/bin/*llvm*")
+            if (_COMPILER)
+                set(PICO_COMPILER ${PICO_DEFAULT_CLANG_COMPILER})
+                message("Detected Clang/LLVM so defaulting PICO_COMPILER to `${PICO_COMPILER}`")
+            endif()
+        endif()
+        unset(_COMPILER)
+    endif()
+    if (NOT PICO_COMPILER AND DEFINED PICO_DEFAULT_COMPILER)
+        pico_message("Defaulting compiler (PICO_COMPILER) to '${PICO_DEFAULT_COMPILER}' since not specified or detected.")
         set(PICO_COMPILER ${PICO_DEFAULT_COMPILER})
     endif()
 endif ()
 
-# PICO_CMAKE_CONFIG: PICO_COMPILER, Specifies the compiler family to use, type=string, group=build, default=PICO_DEFAULT_COMPILER which is set based on PICO_PLATFORM, docref=cmake-toolchain-config
+# PICO_CMAKE_CONFIG: PICO_COMPILER, Specifies the compiler family to use, type=string, group=build, default=autodetected or PICO_DEFAULT_COMPILER which is set based on PICO_PLATFORM, docref=cmake-toolchain-config
 # If PICO_COMPILER is specified, set toolchain file to ${PICO_COMPILER}.cmake.
 if (DEFINED PICO_COMPILER)
     # maintain backwards compatibility with RP2040 SDK compilers

cmake/preload/platforms/rp2040.cmake

@@ -1,2 +1,4 @@
-set(PICO_DEFAULT_COMPILER "pico_arm_cortex_m0plus_gcc")
+set(PICO_DEFAULT_GCC_COMPILER "pico_arm_cortex_m0plus_gcc")
+set(PICO_DEFAULT_CLANG_COMPILER "pico_arm_cortex_m0plus_clang")
+set(PICO_DEFAULT_COMPILER ${PICO_DEFAULT_GCC_COMPILER})
 set(PICO_CHIP rp2040)

cmake/preload/platforms/rp2350-arm-s.cmake

@@ -1,3 +1,5 @@
-set(PICO_DEFAULT_COMPILER "pico_arm_cortex_m33_gcc")
+set(PICO_DEFAULT_GCC_COMPILER "pico_arm_cortex_m33_gcc")
+set(PICO_DEFAULT_CLANG_COMPILER "pico_arm_cortex_m33_clang")
+set(PICO_DEFAULT_COMPILER ${PICO_DEFAULT_GCC_COMPILER})
 set(PICO_CHIP rp2350)
 

cmake/preload/platforms/rp2350-riscv.cmake

@@ -1,3 +1,5 @@
-set(PICO_DEFAULT_COMPILER "pico_riscv_gcc")
+set(PICO_DEFAULT_GCC_COMPILER "pico_riscv_gcc")
+#set(PICO_DEFAULT_CLANG_COMPILER ...)
+set(PICO_DEFAULT_COMPILER ${PICO_DEFAULT_GCC_COMPILER})
 set(PICO_CHIP rp2350)